[3] | 1 | # engine/base.py |
---|
| 2 | # Copyright (C) 2005, 2006, 2007, 2008, 2009 Michael Bayer mike_mp@zzzcomputing.com |
---|
| 3 | # |
---|
| 4 | # This module is part of SQLAlchemy and is released under |
---|
| 5 | # the MIT License: http://www.opensource.org/licenses/mit-license.php |
---|
| 6 | |
---|
| 7 | |
---|
| 8 | """Basic components for SQL execution and interfacing with DB-API. |
---|
| 9 | |
---|
| 10 | Defines the basic components used to interface DB-API modules with |
---|
| 11 | higher-level statement-construction, connection-management, execution |
---|
| 12 | and result contexts. |
---|
| 13 | |
---|
| 14 | """ |
---|
| 15 | |
---|
| 16 | __all__ = ['BufferedColumnResultProxy', 'BufferedColumnRow', 'BufferedRowResultProxy', 'Compiled', 'Connectable', |
---|
| 17 | 'Connection', 'DefaultRunner', 'Dialect', 'Engine', 'ExecutionContext', 'NestedTransaction', 'ResultProxy', |
---|
| 18 | 'RootTransaction', 'RowProxy', 'SchemaIterator', 'StringIO', 'Transaction', 'TwoPhaseTransaction', 'connection_memoize'] |
---|
| 19 | |
---|
| 20 | import inspect, StringIO |
---|
| 21 | from sqlalchemy import exc, schema, util, types, log |
---|
| 22 | from sqlalchemy.sql import expression |
---|
| 23 | |
---|
| 24 | class Dialect(object): |
---|
| 25 | """Define the behavior of a specific database and DB-API combination. |
---|
| 26 | |
---|
| 27 | Any aspect of metadata definition, SQL query generation, |
---|
| 28 | execution, result-set handling, or anything else which varies |
---|
| 29 | between databases is defined under the general category of the |
---|
| 30 | Dialect. The Dialect acts as a factory for other |
---|
| 31 | database-specific object implementations including |
---|
| 32 | ExecutionContext, Compiled, DefaultGenerator, and TypeEngine. |
---|
| 33 | |
---|
| 34 | All Dialects implement the following attributes: |
---|
| 35 | |
---|
| 36 | name |
---|
| 37 | identifying name for the dialect (i.e. 'sqlite') |
---|
| 38 | |
---|
| 39 | positional |
---|
| 40 | True if the paramstyle for this Dialect is positional. |
---|
| 41 | |
---|
| 42 | paramstyle |
---|
| 43 | the paramstyle to be used (some DB-APIs support multiple |
---|
| 44 | paramstyles). |
---|
| 45 | |
---|
| 46 | convert_unicode |
---|
| 47 | True if Unicode conversion should be applied to all ``str`` |
---|
| 48 | types. |
---|
| 49 | |
---|
| 50 | encoding |
---|
| 51 | type of encoding to use for unicode, usually defaults to |
---|
| 52 | 'utf-8'. |
---|
| 53 | |
---|
| 54 | schemagenerator |
---|
| 55 | a :class:`~sqlalchemy.schema.SchemaVisitor` class which generates |
---|
| 56 | schemas. |
---|
| 57 | |
---|
| 58 | schemadropper |
---|
| 59 | a :class:`~sqlalchemy.schema.SchemaVisitor` class which drops schemas. |
---|
| 60 | |
---|
| 61 | defaultrunner |
---|
| 62 | a :class:`~sqlalchemy.schema.SchemaVisitor` class which executes |
---|
| 63 | defaults. |
---|
| 64 | |
---|
| 65 | statement_compiler |
---|
| 66 | a :class:`~sqlalchemy.engine.base.Compiled` class used to compile SQL |
---|
| 67 | statements |
---|
| 68 | |
---|
| 69 | preparer |
---|
| 70 | a :class:`~sqlalchemy.sql.compiler.IdentifierPreparer` class used to |
---|
| 71 | quote identifiers. |
---|
| 72 | |
---|
| 73 | supports_alter |
---|
| 74 | ``True`` if the database supports ``ALTER TABLE``. |
---|
| 75 | |
---|
| 76 | max_identifier_length |
---|
| 77 | The maximum length of identifier names. |
---|
| 78 | |
---|
| 79 | supports_unicode_statements |
---|
| 80 | Indicate whether the DB-API can receive SQL statements as Python unicode strings |
---|
| 81 | |
---|
| 82 | supports_sane_rowcount |
---|
| 83 | Indicate whether the dialect properly implements rowcount for ``UPDATE`` and ``DELETE`` statements. |
---|
| 84 | |
---|
| 85 | supports_sane_multi_rowcount |
---|
| 86 | Indicate whether the dialect properly implements rowcount for ``UPDATE`` and ``DELETE`` statements |
---|
| 87 | when executed via executemany. |
---|
| 88 | |
---|
| 89 | preexecute_pk_sequences |
---|
| 90 | Indicate if the dialect should pre-execute sequences on primary key |
---|
| 91 | columns during an INSERT, if it's desired that the new row's primary key |
---|
| 92 | be available after execution. |
---|
| 93 | |
---|
| 94 | supports_pk_autoincrement |
---|
| 95 | Indicates if the dialect should allow the database to passively assign |
---|
| 96 | a primary key column value. |
---|
| 97 | |
---|
| 98 | dbapi_type_map |
---|
| 99 | A mapping of DB-API type objects present in this Dialect's |
---|
| 100 | DB-API implmentation mapped to TypeEngine implementations used |
---|
| 101 | by the dialect. |
---|
| 102 | |
---|
| 103 | This is used to apply types to result sets based on the DB-API |
---|
| 104 | types present in cursor.description; it only takes effect for |
---|
| 105 | result sets against textual statements where no explicit |
---|
| 106 | typemap was present. |
---|
| 107 | |
---|
| 108 | supports_default_values |
---|
| 109 | Indicates if the construct ``INSERT INTO tablename DEFAULT VALUES`` is supported |
---|
| 110 | |
---|
| 111 | description_encoding |
---|
| 112 | type of encoding to use for unicode when working with metadata |
---|
| 113 | descriptions. If set to ``None`` no encoding will be done. |
---|
| 114 | This usually defaults to 'utf-8'. |
---|
| 115 | """ |
---|
| 116 | |
---|
| 117 | def create_connect_args(self, url): |
---|
| 118 | """Build DB-API compatible connection arguments. |
---|
| 119 | |
---|
| 120 | Given a :class:`~sqlalchemy.engine.url.URL` object, returns a tuple |
---|
| 121 | consisting of a `*args`/`**kwargs` suitable to send directly |
---|
| 122 | to the dbapi's connect function. |
---|
| 123 | """ |
---|
| 124 | |
---|
| 125 | raise NotImplementedError() |
---|
| 126 | |
---|
| 127 | |
---|
| 128 | def type_descriptor(self, typeobj): |
---|
| 129 | """Transform a generic type to a database-specific type. |
---|
| 130 | |
---|
| 131 | Transforms the given :class:`~sqlalchemy.types.TypeEngine` instance |
---|
| 132 | from generic to database-specific. |
---|
| 133 | |
---|
| 134 | Subclasses will usually use the |
---|
| 135 | :func:`~sqlalchemy.types.adapt_type` method in the types module to |
---|
| 136 | make this job easy. |
---|
| 137 | """ |
---|
| 138 | |
---|
| 139 | raise NotImplementedError() |
---|
| 140 | |
---|
| 141 | |
---|
| 142 | def server_version_info(self, connection): |
---|
| 143 | """Return a tuple of the database's version number.""" |
---|
| 144 | |
---|
| 145 | raise NotImplementedError() |
---|
| 146 | |
---|
| 147 | def reflecttable(self, connection, table, include_columns=None): |
---|
| 148 | """Load table description from the database. |
---|
| 149 | |
---|
| 150 | Given a :class:`~sqlalchemy.engine.Connection` and a |
---|
| 151 | :class:`~sqlalchemy.schema.Table` object, reflect its columns and |
---|
| 152 | properties from the database. If include_columns (a list or |
---|
| 153 | set) is specified, limit the autoload to the given column |
---|
| 154 | names. |
---|
| 155 | """ |
---|
| 156 | |
---|
| 157 | raise NotImplementedError() |
---|
| 158 | |
---|
| 159 | def has_table(self, connection, table_name, schema=None): |
---|
| 160 | """Check the existence of a particular table in the database. |
---|
| 161 | |
---|
| 162 | Given a :class:`~sqlalchemy.engine.Connection` object and a string |
---|
| 163 | `table_name`, return True if the given table (possibly within |
---|
| 164 | the specified `schema`) exists in the database, False |
---|
| 165 | otherwise. |
---|
| 166 | """ |
---|
| 167 | |
---|
| 168 | raise NotImplementedError() |
---|
| 169 | |
---|
| 170 | def has_sequence(self, connection, sequence_name, schema=None): |
---|
| 171 | """Check the existence of a particular sequence in the database. |
---|
| 172 | |
---|
| 173 | Given a :class:`~sqlalchemy.engine.Connection` object and a string |
---|
| 174 | `sequence_name`, return True if the given sequence exists in |
---|
| 175 | the database, False otherwise. |
---|
| 176 | """ |
---|
| 177 | |
---|
| 178 | raise NotImplementedError() |
---|
| 179 | |
---|
| 180 | def get_default_schema_name(self, connection): |
---|
| 181 | """Return the string name of the currently selected schema given a :class:`~sqlalchemy.engine.Connection`.""" |
---|
| 182 | |
---|
| 183 | raise NotImplementedError() |
---|
| 184 | |
---|
| 185 | def do_begin(self, connection): |
---|
| 186 | """Provide an implementation of *connection.begin()*, given a DB-API connection.""" |
---|
| 187 | |
---|
| 188 | raise NotImplementedError() |
---|
| 189 | |
---|
| 190 | def do_rollback(self, connection): |
---|
| 191 | """Provide an implementation of *connection.rollback()*, given a DB-API connection.""" |
---|
| 192 | |
---|
| 193 | raise NotImplementedError() |
---|
| 194 | |
---|
| 195 | def create_xid(self): |
---|
| 196 | """Create a two-phase transaction ID. |
---|
| 197 | |
---|
| 198 | This id will be passed to do_begin_twophase(), |
---|
| 199 | do_rollback_twophase(), do_commit_twophase(). Its format is |
---|
| 200 | unspecified. |
---|
| 201 | """ |
---|
| 202 | |
---|
| 203 | raise NotImplementedError() |
---|
| 204 | |
---|
| 205 | def do_commit(self, connection): |
---|
| 206 | """Provide an implementation of *connection.commit()*, given a DB-API connection.""" |
---|
| 207 | |
---|
| 208 | raise NotImplementedError() |
---|
| 209 | |
---|
| 210 | def do_savepoint(self, connection, name): |
---|
| 211 | """Create a savepoint with the given name on a SQLAlchemy connection.""" |
---|
| 212 | |
---|
| 213 | raise NotImplementedError() |
---|
| 214 | |
---|
| 215 | def do_rollback_to_savepoint(self, connection, name): |
---|
| 216 | """Rollback a SQL Alchemy connection to the named savepoint.""" |
---|
| 217 | |
---|
| 218 | raise NotImplementedError() |
---|
| 219 | |
---|
| 220 | def do_release_savepoint(self, connection, name): |
---|
| 221 | """Release the named savepoint on a SQL Alchemy connection.""" |
---|
| 222 | |
---|
| 223 | raise NotImplementedError() |
---|
| 224 | |
---|
| 225 | def do_begin_twophase(self, connection, xid): |
---|
| 226 | """Begin a two phase transaction on the given connection.""" |
---|
| 227 | |
---|
| 228 | raise NotImplementedError() |
---|
| 229 | |
---|
| 230 | def do_prepare_twophase(self, connection, xid): |
---|
| 231 | """Prepare a two phase transaction on the given connection.""" |
---|
| 232 | |
---|
| 233 | raise NotImplementedError() |
---|
| 234 | |
---|
| 235 | def do_rollback_twophase(self, connection, xid, is_prepared=True, recover=False): |
---|
| 236 | """Rollback a two phase transaction on the given connection.""" |
---|
| 237 | |
---|
| 238 | raise NotImplementedError() |
---|
| 239 | |
---|
| 240 | def do_commit_twophase(self, connection, xid, is_prepared=True, recover=False): |
---|
| 241 | """Commit a two phase transaction on the given connection.""" |
---|
| 242 | |
---|
| 243 | raise NotImplementedError() |
---|
| 244 | |
---|
| 245 | def do_recover_twophase(self, connection): |
---|
| 246 | """Recover list of uncommited prepared two phase transaction identifiers on the given connection.""" |
---|
| 247 | |
---|
| 248 | raise NotImplementedError() |
---|
| 249 | |
---|
| 250 | def do_executemany(self, cursor, statement, parameters, context=None): |
---|
| 251 | """Provide an implementation of *cursor.executemany(statement, parameters)*.""" |
---|
| 252 | |
---|
| 253 | raise NotImplementedError() |
---|
| 254 | |
---|
| 255 | def do_execute(self, cursor, statement, parameters, context=None): |
---|
| 256 | """Provide an implementation of *cursor.execute(statement, parameters)*.""" |
---|
| 257 | |
---|
| 258 | raise NotImplementedError() |
---|
| 259 | |
---|
| 260 | def is_disconnect(self, e): |
---|
| 261 | """Return True if the given DB-API error indicates an invalid connection""" |
---|
| 262 | |
---|
| 263 | raise NotImplementedError() |
---|
| 264 | |
---|
| 265 | |
---|
| 266 | class ExecutionContext(object): |
---|
| 267 | """A messenger object for a Dialect that corresponds to a single execution. |
---|
| 268 | |
---|
| 269 | ExecutionContext should have these datamembers: |
---|
| 270 | |
---|
| 271 | connection |
---|
| 272 | Connection object which can be freely used by default value |
---|
| 273 | generators to execute SQL. This Connection should reference the |
---|
| 274 | same underlying connection/transactional resources of |
---|
| 275 | root_connection. |
---|
| 276 | |
---|
| 277 | root_connection |
---|
| 278 | Connection object which is the source of this ExecutionContext. This |
---|
| 279 | Connection may have close_with_result=True set, in which case it can |
---|
| 280 | only be used once. |
---|
| 281 | |
---|
| 282 | dialect |
---|
| 283 | dialect which created this ExecutionContext. |
---|
| 284 | |
---|
| 285 | cursor |
---|
| 286 | DB-API cursor procured from the connection, |
---|
| 287 | |
---|
| 288 | compiled |
---|
| 289 | if passed to constructor, sqlalchemy.engine.base.Compiled object |
---|
| 290 | being executed, |
---|
| 291 | |
---|
| 292 | statement |
---|
| 293 | string version of the statement to be executed. Is either |
---|
| 294 | passed to the constructor, or must be created from the |
---|
| 295 | sql.Compiled object by the time pre_exec() has completed. |
---|
| 296 | |
---|
| 297 | parameters |
---|
| 298 | bind parameters passed to the execute() method. For compiled |
---|
| 299 | statements, this is a dictionary or list of dictionaries. For |
---|
| 300 | textual statements, it should be in a format suitable for the |
---|
| 301 | dialect's paramstyle (i.e. dict or list of dicts for non |
---|
| 302 | positional, list or list of lists/tuples for positional). |
---|
| 303 | |
---|
| 304 | isinsert |
---|
| 305 | True if the statement is an INSERT. |
---|
| 306 | |
---|
| 307 | isupdate |
---|
| 308 | True if the statement is an UPDATE. |
---|
| 309 | |
---|
| 310 | should_autocommit |
---|
| 311 | True if the statement is a "committable" statement |
---|
| 312 | |
---|
| 313 | postfetch_cols |
---|
| 314 | a list of Column objects for which a server-side default |
---|
| 315 | or inline SQL expression value was fired off. applies to inserts and updates. |
---|
| 316 | |
---|
| 317 | |
---|
| 318 | """ |
---|
| 319 | |
---|
| 320 | def create_cursor(self): |
---|
| 321 | """Return a new cursor generated from this ExecutionContext's connection. |
---|
| 322 | |
---|
| 323 | Some dialects may wish to change the behavior of |
---|
| 324 | connection.cursor(), such as postgres which may return a PG |
---|
| 325 | "server side" cursor. |
---|
| 326 | """ |
---|
| 327 | |
---|
| 328 | raise NotImplementedError() |
---|
| 329 | |
---|
| 330 | def pre_exec(self): |
---|
| 331 | """Called before an execution of a compiled statement. |
---|
| 332 | |
---|
| 333 | If a compiled statement was passed to this ExecutionContext, |
---|
| 334 | the `statement` and `parameters` datamembers must be |
---|
| 335 | initialized after this statement is complete. |
---|
| 336 | """ |
---|
| 337 | |
---|
| 338 | raise NotImplementedError() |
---|
| 339 | |
---|
| 340 | def post_exec(self): |
---|
| 341 | """Called after the execution of a compiled statement. |
---|
| 342 | |
---|
| 343 | If a compiled statement was passed to this ExecutionContext, |
---|
| 344 | the `last_insert_ids`, `last_inserted_params`, etc. |
---|
| 345 | datamembers should be available after this method completes. |
---|
| 346 | """ |
---|
| 347 | |
---|
| 348 | raise NotImplementedError() |
---|
| 349 | |
---|
| 350 | def result(self): |
---|
| 351 | """Return a result object corresponding to this ExecutionContext. |
---|
| 352 | |
---|
| 353 | Returns a ResultProxy. |
---|
| 354 | """ |
---|
| 355 | |
---|
| 356 | raise NotImplementedError() |
---|
| 357 | |
---|
| 358 | def handle_dbapi_exception(self, e): |
---|
| 359 | """Receive a DBAPI exception which occured upon execute, result fetch, etc.""" |
---|
| 360 | |
---|
| 361 | raise NotImplementedError() |
---|
| 362 | |
---|
| 363 | def should_autocommit_text(self, statement): |
---|
| 364 | """Parse the given textual statement and return True if it refers to a "committable" statement""" |
---|
| 365 | |
---|
| 366 | raise NotImplementedError() |
---|
| 367 | |
---|
| 368 | def last_inserted_ids(self): |
---|
| 369 | """Return the list of the primary key values for the last insert statement executed. |
---|
| 370 | |
---|
| 371 | This does not apply to straight textual clauses; only to |
---|
| 372 | ``sql.Insert`` objects compiled against a ``schema.Table`` |
---|
| 373 | object. The order of items in the list is the same as that of |
---|
| 374 | the Table's 'primary_key' attribute. |
---|
| 375 | """ |
---|
| 376 | |
---|
| 377 | raise NotImplementedError() |
---|
| 378 | |
---|
| 379 | def last_inserted_params(self): |
---|
| 380 | """Return a dictionary of the full parameter dictionary for the last compiled INSERT statement. |
---|
| 381 | |
---|
| 382 | Includes any ColumnDefaults or Sequences that were pre-executed. |
---|
| 383 | """ |
---|
| 384 | |
---|
| 385 | raise NotImplementedError() |
---|
| 386 | |
---|
| 387 | def last_updated_params(self): |
---|
| 388 | """Return a dictionary of the full parameter dictionary for the last compiled UPDATE statement. |
---|
| 389 | |
---|
| 390 | Includes any ColumnDefaults that were pre-executed. |
---|
| 391 | """ |
---|
| 392 | |
---|
| 393 | raise NotImplementedError() |
---|
| 394 | |
---|
| 395 | def lastrow_has_defaults(self): |
---|
| 396 | """Return True if the last INSERT or UPDATE row contained |
---|
| 397 | inlined or database-side defaults. |
---|
| 398 | """ |
---|
| 399 | |
---|
| 400 | raise NotImplementedError() |
---|
| 401 | |
---|
| 402 | |
---|
| 403 | class Compiled(object): |
---|
| 404 | """Represent a compiled SQL expression. |
---|
| 405 | |
---|
| 406 | The ``__str__`` method of the ``Compiled`` object should produce |
---|
| 407 | the actual text of the statement. ``Compiled`` objects are |
---|
| 408 | specific to their underlying database dialect, and also may |
---|
| 409 | or may not be specific to the columns referenced within a |
---|
| 410 | particular set of bind parameters. In no case should the |
---|
| 411 | ``Compiled`` object be dependent on the actual values of those |
---|
| 412 | bind parameters, even though it may reference those values as |
---|
| 413 | defaults. |
---|
| 414 | """ |
---|
| 415 | |
---|
| 416 | def __init__(self, dialect, statement, column_keys=None, bind=None): |
---|
| 417 | """Construct a new ``Compiled`` object. |
---|
| 418 | |
---|
| 419 | dialect |
---|
| 420 | ``Dialect`` to compile against. |
---|
| 421 | |
---|
| 422 | statement |
---|
| 423 | ``ClauseElement`` to be compiled. |
---|
| 424 | |
---|
| 425 | column_keys |
---|
| 426 | a list of column names to be compiled into an INSERT or UPDATE |
---|
| 427 | statement. |
---|
| 428 | |
---|
| 429 | bind |
---|
| 430 | Optional Engine or Connection to compile this statement against. |
---|
| 431 | |
---|
| 432 | """ |
---|
| 433 | self.dialect = dialect |
---|
| 434 | self.statement = statement |
---|
| 435 | self.column_keys = column_keys |
---|
| 436 | self.bind = bind |
---|
| 437 | self.can_execute = statement.supports_execution |
---|
| 438 | |
---|
| 439 | def compile(self): |
---|
| 440 | """Produce the internal string representation of this element.""" |
---|
| 441 | |
---|
| 442 | raise NotImplementedError() |
---|
| 443 | |
---|
| 444 | def __str__(self): |
---|
| 445 | """Return the string text of the generated SQL statement.""" |
---|
| 446 | |
---|
| 447 | raise NotImplementedError() |
---|
| 448 | |
---|
| 449 | @util.deprecated('Deprecated. Use construct_params(). ' |
---|
| 450 | '(supports Unicode key names.)') |
---|
| 451 | def get_params(self, **params): |
---|
| 452 | return self.construct_params(params) |
---|
| 453 | |
---|
| 454 | def construct_params(self, params): |
---|
| 455 | """Return the bind params for this compiled object. |
---|
| 456 | |
---|
| 457 | `params` is a dict of string/object pairs whos |
---|
| 458 | values will override bind values compiled in |
---|
| 459 | to the statement. |
---|
| 460 | """ |
---|
| 461 | raise NotImplementedError() |
---|
| 462 | |
---|
| 463 | def execute(self, *multiparams, **params): |
---|
| 464 | """Execute this compiled object.""" |
---|
| 465 | |
---|
| 466 | e = self.bind |
---|
| 467 | if e is None: |
---|
| 468 | raise exc.UnboundExecutionError("This Compiled object is not bound to any Engine or Connection.") |
---|
| 469 | return e._execute_compiled(self, multiparams, params) |
---|
| 470 | |
---|
| 471 | def scalar(self, *multiparams, **params): |
---|
| 472 | """Execute this compiled object and return the result's scalar value.""" |
---|
| 473 | |
---|
| 474 | return self.execute(*multiparams, **params).scalar() |
---|
| 475 | |
---|
| 476 | |
---|
| 477 | class Connectable(object): |
---|
| 478 | """Interface for an object which supports execution of SQL constructs. |
---|
| 479 | |
---|
| 480 | The two implementations of ``Connectable`` are :class:`Connection` and |
---|
| 481 | :class:`Engine`. |
---|
| 482 | |
---|
| 483 | """ |
---|
| 484 | |
---|
| 485 | def contextual_connect(self): |
---|
| 486 | """Return a Connection object which may be part of an ongoing context.""" |
---|
| 487 | |
---|
| 488 | raise NotImplementedError() |
---|
| 489 | |
---|
| 490 | def create(self, entity, **kwargs): |
---|
| 491 | """Create a table or index given an appropriate schema object.""" |
---|
| 492 | |
---|
| 493 | raise NotImplementedError() |
---|
| 494 | |
---|
| 495 | def drop(self, entity, **kwargs): |
---|
| 496 | """Drop a table or index given an appropriate schema object.""" |
---|
| 497 | |
---|
| 498 | raise NotImplementedError() |
---|
| 499 | |
---|
| 500 | def execute(self, object, *multiparams, **params): |
---|
| 501 | raise NotImplementedError() |
---|
| 502 | |
---|
| 503 | def _execute_clauseelement(self, elem, multiparams=None, params=None): |
---|
| 504 | raise NotImplementedError() |
---|
| 505 | |
---|
| 506 | class Connection(Connectable): |
---|
| 507 | """Provides high-level functionality for a wrapped DB-API connection. |
---|
| 508 | |
---|
| 509 | Provides execution support for string-based SQL statements as well |
---|
| 510 | as ClauseElement, Compiled and DefaultGenerator objects. Provides |
---|
| 511 | a begin method to return Transaction objects. |
---|
| 512 | |
---|
| 513 | The Connection object is **not** thread-safe. |
---|
| 514 | |
---|
| 515 | .. index:: |
---|
| 516 | single: thread safety; Connection |
---|
| 517 | |
---|
| 518 | """ |
---|
| 519 | |
---|
| 520 | def __init__(self, engine, connection=None, close_with_result=False, |
---|
| 521 | _branch=False): |
---|
| 522 | """Construct a new Connection. |
---|
| 523 | |
---|
| 524 | Connection objects are typically constructed by an |
---|
| 525 | :class:`~sqlalchemy.engine.Engine`, see the ``connect()`` and |
---|
| 526 | ``contextual_connect()`` methods of Engine. |
---|
| 527 | |
---|
| 528 | """ |
---|
| 529 | |
---|
| 530 | self.engine = engine |
---|
| 531 | self.__connection = connection or engine.raw_connection() |
---|
| 532 | self.__transaction = None |
---|
| 533 | self.__close_with_result = close_with_result |
---|
| 534 | self.__savepoint_seq = 0 |
---|
| 535 | self.__branch = _branch |
---|
| 536 | self.__invalid = False |
---|
| 537 | |
---|
| 538 | def _branch(self): |
---|
| 539 | """Return a new Connection which references this Connection's |
---|
| 540 | engine and connection; but does not have close_with_result enabled, |
---|
| 541 | and also whose close() method does nothing. |
---|
| 542 | |
---|
| 543 | This is used to execute "sub" statements within a single execution, |
---|
| 544 | usually an INSERT statement. |
---|
| 545 | |
---|
| 546 | """ |
---|
| 547 | return self.engine.Connection(self.engine, self.__connection, _branch=True) |
---|
| 548 | |
---|
| 549 | @property |
---|
| 550 | def dialect(self): |
---|
| 551 | "Dialect used by this Connection." |
---|
| 552 | |
---|
| 553 | return self.engine.dialect |
---|
| 554 | |
---|
| 555 | @property |
---|
| 556 | def closed(self): |
---|
| 557 | """return True if this connection is closed.""" |
---|
| 558 | |
---|
| 559 | return not self.__invalid and '_Connection__connection' not in self.__dict__ |
---|
| 560 | |
---|
| 561 | @property |
---|
| 562 | def invalidated(self): |
---|
| 563 | """return True if this connection was invalidated.""" |
---|
| 564 | |
---|
| 565 | return self.__invalid |
---|
| 566 | |
---|
| 567 | @property |
---|
| 568 | def connection(self): |
---|
| 569 | "The underlying DB-API connection managed by this Connection." |
---|
| 570 | |
---|
| 571 | try: |
---|
| 572 | return self.__connection |
---|
| 573 | except AttributeError: |
---|
| 574 | if self.__invalid: |
---|
| 575 | if self.__transaction is not None: |
---|
| 576 | raise exc.InvalidRequestError("Can't reconnect until invalid transaction is rolled back") |
---|
| 577 | self.__connection = self.engine.raw_connection() |
---|
| 578 | self.__invalid = False |
---|
| 579 | return self.__connection |
---|
| 580 | raise exc.InvalidRequestError("This Connection is closed") |
---|
| 581 | |
---|
| 582 | @property |
---|
| 583 | def should_close_with_result(self): |
---|
| 584 | """Indicates if this Connection should be closed when a corresponding |
---|
| 585 | ResultProxy is closed; this is essentially an auto-release mode. |
---|
| 586 | |
---|
| 587 | """ |
---|
| 588 | return self.__close_with_result |
---|
| 589 | |
---|
| 590 | @property |
---|
| 591 | def info(self): |
---|
| 592 | """A collection of per-DB-API connection instance properties.""" |
---|
| 593 | return self.connection.info |
---|
| 594 | |
---|
| 595 | def connect(self): |
---|
| 596 | """Returns self. |
---|
| 597 | |
---|
| 598 | This ``Connectable`` interface method returns self, allowing |
---|
| 599 | Connections to be used interchangably with Engines in most |
---|
| 600 | situations that require a bind. |
---|
| 601 | |
---|
| 602 | """ |
---|
| 603 | return self |
---|
| 604 | |
---|
| 605 | def contextual_connect(self, **kwargs): |
---|
| 606 | """Returns self. |
---|
| 607 | |
---|
| 608 | This ``Connectable`` interface method returns self, allowing |
---|
| 609 | Connections to be used interchangably with Engines in most |
---|
| 610 | situations that require a bind. |
---|
| 611 | |
---|
| 612 | """ |
---|
| 613 | return self |
---|
| 614 | |
---|
| 615 | def invalidate(self, exception=None): |
---|
| 616 | """Invalidate the underlying DBAPI connection associated with this Connection. |
---|
| 617 | |
---|
| 618 | The underlying DB-API connection is literally closed (if |
---|
| 619 | possible), and is discarded. Its source connection pool will |
---|
| 620 | typically lazily create a new connection to replace it. |
---|
| 621 | |
---|
| 622 | Upon the next usage, this Connection will attempt to reconnect |
---|
| 623 | to the pool with a new connection. |
---|
| 624 | |
---|
| 625 | Transactions in progress remain in an "opened" state (even though |
---|
| 626 | the actual transaction is gone); these must be explicitly |
---|
| 627 | rolled back before a reconnect on this Connection can proceed. This |
---|
| 628 | is to prevent applications from accidentally continuing their transactional |
---|
| 629 | operations in a non-transactional state. |
---|
| 630 | |
---|
| 631 | """ |
---|
| 632 | if self.closed: |
---|
| 633 | raise exc.InvalidRequestError("This Connection is closed") |
---|
| 634 | |
---|
| 635 | if self.__connection.is_valid: |
---|
| 636 | self.__connection.invalidate(exception) |
---|
| 637 | del self.__connection |
---|
| 638 | self.__invalid = True |
---|
| 639 | |
---|
| 640 | def detach(self): |
---|
| 641 | """Detach the underlying DB-API connection from its connection pool. |
---|
| 642 | |
---|
| 643 | This Connection instance will remain useable. When closed, |
---|
| 644 | the DB-API connection will be literally closed and not |
---|
| 645 | returned to its pool. The pool will typically lazily create a |
---|
| 646 | new connection to replace the detached connection. |
---|
| 647 | |
---|
| 648 | This method can be used to insulate the rest of an application |
---|
| 649 | from a modified state on a connection (such as a transaction |
---|
| 650 | isolation level or similar). Also see |
---|
| 651 | :class:`~sqlalchemy.interfaces.PoolListener` for a mechanism to modify |
---|
| 652 | connection state when connections leave and return to their |
---|
| 653 | connection pool. |
---|
| 654 | |
---|
| 655 | """ |
---|
| 656 | self.__connection.detach() |
---|
| 657 | |
---|
| 658 | def begin(self): |
---|
| 659 | """Begin a transaction and return a Transaction handle. |
---|
| 660 | |
---|
| 661 | Repeated calls to ``begin`` on the same Connection will create |
---|
| 662 | a lightweight, emulated nested transaction. Only the |
---|
| 663 | outermost transaction may ``commit``. Calls to ``commit`` on |
---|
| 664 | inner transactions are ignored. Any transaction in the |
---|
| 665 | hierarchy may ``rollback``, however. |
---|
| 666 | |
---|
| 667 | """ |
---|
| 668 | if self.__transaction is None: |
---|
| 669 | self.__transaction = RootTransaction(self) |
---|
| 670 | else: |
---|
| 671 | return Transaction(self, self.__transaction) |
---|
| 672 | return self.__transaction |
---|
| 673 | |
---|
| 674 | def begin_nested(self): |
---|
| 675 | """Begin a nested transaction and return a Transaction handle. |
---|
| 676 | |
---|
| 677 | Nested transactions require SAVEPOINT support in the |
---|
| 678 | underlying database. Any transaction in the hierarchy may |
---|
| 679 | ``commit`` and ``rollback``, however the outermost transaction |
---|
| 680 | still controls the overall ``commit`` or ``rollback`` of the |
---|
| 681 | transaction of a whole. |
---|
| 682 | """ |
---|
| 683 | |
---|
| 684 | if self.__transaction is None: |
---|
| 685 | self.__transaction = RootTransaction(self) |
---|
| 686 | else: |
---|
| 687 | self.__transaction = NestedTransaction(self, self.__transaction) |
---|
| 688 | return self.__transaction |
---|
| 689 | |
---|
| 690 | def begin_twophase(self, xid=None): |
---|
| 691 | """Begin a two-phase or XA transaction and return a Transaction handle. |
---|
| 692 | |
---|
| 693 | xid |
---|
| 694 | the two phase transaction id. If not supplied, a random id |
---|
| 695 | will be generated. |
---|
| 696 | """ |
---|
| 697 | |
---|
| 698 | if self.__transaction is not None: |
---|
| 699 | raise exc.InvalidRequestError( |
---|
| 700 | "Cannot start a two phase transaction when a transaction " |
---|
| 701 | "is already in progress.") |
---|
| 702 | if xid is None: |
---|
| 703 | xid = self.engine.dialect.create_xid(); |
---|
| 704 | self.__transaction = TwoPhaseTransaction(self, xid) |
---|
| 705 | return self.__transaction |
---|
| 706 | |
---|
| 707 | def recover_twophase(self): |
---|
| 708 | return self.engine.dialect.do_recover_twophase(self) |
---|
| 709 | |
---|
| 710 | def rollback_prepared(self, xid, recover=False): |
---|
| 711 | self.engine.dialect.do_rollback_twophase(self, xid, recover=recover) |
---|
| 712 | |
---|
| 713 | def commit_prepared(self, xid, recover=False): |
---|
| 714 | self.engine.dialect.do_commit_twophase(self, xid, recover=recover) |
---|
| 715 | |
---|
| 716 | def in_transaction(self): |
---|
| 717 | """Return True if a transaction is in progress.""" |
---|
| 718 | |
---|
| 719 | return self.__transaction is not None |
---|
| 720 | |
---|
| 721 | def _begin_impl(self): |
---|
| 722 | if self.engine._should_log_info: |
---|
| 723 | self.engine.logger.info("BEGIN") |
---|
| 724 | try: |
---|
| 725 | self.engine.dialect.do_begin(self.connection) |
---|
| 726 | except Exception, e: |
---|
| 727 | self._handle_dbapi_exception(e, None, None, None, None) |
---|
| 728 | raise |
---|
| 729 | |
---|
| 730 | def _rollback_impl(self): |
---|
| 731 | if not self.closed and not self.invalidated and self.__connection.is_valid: |
---|
| 732 | if self.engine._should_log_info: |
---|
| 733 | self.engine.logger.info("ROLLBACK") |
---|
| 734 | try: |
---|
| 735 | self.engine.dialect.do_rollback(self.connection) |
---|
| 736 | self.__transaction = None |
---|
| 737 | except Exception, e: |
---|
| 738 | self._handle_dbapi_exception(e, None, None, None, None) |
---|
| 739 | raise |
---|
| 740 | else: |
---|
| 741 | self.__transaction = None |
---|
| 742 | |
---|
| 743 | def _commit_impl(self): |
---|
| 744 | if self.engine._should_log_info: |
---|
| 745 | self.engine.logger.info("COMMIT") |
---|
| 746 | try: |
---|
| 747 | self.engine.dialect.do_commit(self.connection) |
---|
| 748 | self.__transaction = None |
---|
| 749 | except Exception, e: |
---|
| 750 | self._handle_dbapi_exception(e, None, None, None, None) |
---|
| 751 | raise |
---|
| 752 | |
---|
| 753 | def _savepoint_impl(self, name=None): |
---|
| 754 | if name is None: |
---|
| 755 | self.__savepoint_seq += 1 |
---|
| 756 | name = 'sa_savepoint_%s' % self.__savepoint_seq |
---|
| 757 | if self.__connection.is_valid: |
---|
| 758 | self.engine.dialect.do_savepoint(self, name) |
---|
| 759 | return name |
---|
| 760 | |
---|
| 761 | def _rollback_to_savepoint_impl(self, name, context): |
---|
| 762 | if self.__connection.is_valid: |
---|
| 763 | self.engine.dialect.do_rollback_to_savepoint(self, name) |
---|
| 764 | self.__transaction = context |
---|
| 765 | |
---|
| 766 | def _release_savepoint_impl(self, name, context): |
---|
| 767 | if self.__connection.is_valid: |
---|
| 768 | self.engine.dialect.do_release_savepoint(self, name) |
---|
| 769 | self.__transaction = context |
---|
| 770 | |
---|
| 771 | def _begin_twophase_impl(self, xid): |
---|
| 772 | if self.__connection.is_valid: |
---|
| 773 | self.engine.dialect.do_begin_twophase(self, xid) |
---|
| 774 | |
---|
| 775 | def _prepare_twophase_impl(self, xid): |
---|
| 776 | if self.__connection.is_valid: |
---|
| 777 | assert isinstance(self.__transaction, TwoPhaseTransaction) |
---|
| 778 | self.engine.dialect.do_prepare_twophase(self, xid) |
---|
| 779 | |
---|
| 780 | def _rollback_twophase_impl(self, xid, is_prepared): |
---|
| 781 | if self.__connection.is_valid: |
---|
| 782 | assert isinstance(self.__transaction, TwoPhaseTransaction) |
---|
| 783 | self.engine.dialect.do_rollback_twophase(self, xid, is_prepared) |
---|
| 784 | self.__transaction = None |
---|
| 785 | |
---|
| 786 | def _commit_twophase_impl(self, xid, is_prepared): |
---|
| 787 | if self.__connection.is_valid: |
---|
| 788 | assert isinstance(self.__transaction, TwoPhaseTransaction) |
---|
| 789 | self.engine.dialect.do_commit_twophase(self, xid, is_prepared) |
---|
| 790 | self.__transaction = None |
---|
| 791 | |
---|
| 792 | def _autorollback(self): |
---|
| 793 | if not self.in_transaction(): |
---|
| 794 | self._rollback_impl() |
---|
| 795 | |
---|
| 796 | def close(self): |
---|
| 797 | """Close this Connection.""" |
---|
| 798 | |
---|
| 799 | try: |
---|
| 800 | conn = self.__connection |
---|
| 801 | except AttributeError: |
---|
| 802 | return |
---|
| 803 | if not self.__branch: |
---|
| 804 | conn.close() |
---|
| 805 | self.__invalid = False |
---|
| 806 | del self.__connection |
---|
| 807 | |
---|
| 808 | def scalar(self, object, *multiparams, **params): |
---|
| 809 | """Executes and returns the first column of the first row. |
---|
| 810 | |
---|
| 811 | The underlying result/cursor is closed after execution. |
---|
| 812 | """ |
---|
| 813 | |
---|
| 814 | return self.execute(object, *multiparams, **params).scalar() |
---|
| 815 | |
---|
| 816 | def statement_compiler(self, statement, **kwargs): |
---|
| 817 | return self.dialect.statement_compiler(self.dialect, statement, bind=self, **kwargs) |
---|
| 818 | |
---|
| 819 | def execute(self, object, *multiparams, **params): |
---|
| 820 | """Executes and returns a ResultProxy.""" |
---|
| 821 | |
---|
| 822 | for c in type(object).__mro__: |
---|
| 823 | if c in Connection.executors: |
---|
| 824 | return Connection.executors[c](self, object, multiparams, params) |
---|
| 825 | else: |
---|
| 826 | raise exc.InvalidRequestError("Unexecutable object type: " + str(type(object))) |
---|
| 827 | |
---|
| 828 | def __distill_params(self, multiparams, params): |
---|
| 829 | """given arguments from the calling form *multiparams, **params, return a list |
---|
| 830 | of bind parameter structures, usually a list of dictionaries. |
---|
| 831 | |
---|
| 832 | in the case of 'raw' execution which accepts positional parameters, |
---|
| 833 | it may be a list of tuples or lists.""" |
---|
| 834 | |
---|
| 835 | if not multiparams: |
---|
| 836 | if params: |
---|
| 837 | return [params] |
---|
| 838 | else: |
---|
| 839 | return [] |
---|
| 840 | elif len(multiparams) == 1: |
---|
| 841 | zero = multiparams[0] |
---|
| 842 | if isinstance(zero, (list, tuple)): |
---|
| 843 | if not zero or hasattr(zero[0], '__iter__'): |
---|
| 844 | return zero |
---|
| 845 | else: |
---|
| 846 | return [zero] |
---|
| 847 | elif hasattr(zero, 'keys'): |
---|
| 848 | return [zero] |
---|
| 849 | else: |
---|
| 850 | return [[zero]] |
---|
| 851 | else: |
---|
| 852 | if hasattr(multiparams[0], '__iter__'): |
---|
| 853 | return multiparams |
---|
| 854 | else: |
---|
| 855 | return [multiparams] |
---|
| 856 | |
---|
| 857 | def _execute_function(self, func, multiparams, params): |
---|
| 858 | return self._execute_clauseelement(func.select(), multiparams, params) |
---|
| 859 | |
---|
| 860 | def _execute_default(self, default, multiparams, params): |
---|
| 861 | return self.engine.dialect.defaultrunner(self.__create_execution_context()).traverse_single(default) |
---|
| 862 | |
---|
| 863 | def _execute_clauseelement(self, elem, multiparams, params): |
---|
| 864 | params = self.__distill_params(multiparams, params) |
---|
| 865 | if params: |
---|
| 866 | keys = params[0].keys() |
---|
| 867 | else: |
---|
| 868 | keys = [] |
---|
| 869 | |
---|
| 870 | context = self.__create_execution_context( |
---|
| 871 | compiled=elem.compile(dialect=self.dialect, column_keys=keys, inline=len(params) > 1), |
---|
| 872 | parameters=params |
---|
| 873 | ) |
---|
| 874 | return self.__execute_context(context) |
---|
| 875 | |
---|
| 876 | def _execute_compiled(self, compiled, multiparams, params): |
---|
| 877 | """Execute a sql.Compiled object.""" |
---|
| 878 | |
---|
| 879 | context = self.__create_execution_context( |
---|
| 880 | compiled=compiled, |
---|
| 881 | parameters=self.__distill_params(multiparams, params) |
---|
| 882 | ) |
---|
| 883 | return self.__execute_context(context) |
---|
| 884 | |
---|
| 885 | def _execute_text(self, statement, multiparams, params): |
---|
| 886 | parameters = self.__distill_params(multiparams, params) |
---|
| 887 | context = self.__create_execution_context(statement=statement, parameters=parameters) |
---|
| 888 | return self.__execute_context(context) |
---|
| 889 | |
---|
| 890 | def __execute_context(self, context): |
---|
| 891 | if context.compiled: |
---|
| 892 | context.pre_exec() |
---|
| 893 | if context.executemany: |
---|
| 894 | self._cursor_executemany(context.cursor, context.statement, context.parameters, context=context) |
---|
| 895 | else: |
---|
| 896 | self._cursor_execute(context.cursor, context.statement, context.parameters[0], context=context) |
---|
| 897 | if context.compiled: |
---|
| 898 | context.post_exec() |
---|
| 899 | if context.should_autocommit and not self.in_transaction(): |
---|
| 900 | self._commit_impl() |
---|
| 901 | return context.get_result_proxy() |
---|
| 902 | |
---|
| 903 | def _execute_ddl(self, ddl, params, multiparams): |
---|
| 904 | if params: |
---|
| 905 | schema_item, params = params[0], params[1:] |
---|
| 906 | else: |
---|
| 907 | schema_item = None |
---|
| 908 | return ddl(None, schema_item, self, *params, **multiparams) |
---|
| 909 | |
---|
| 910 | def _handle_dbapi_exception(self, e, statement, parameters, cursor, context): |
---|
| 911 | if getattr(self, '_reentrant_error', False): |
---|
| 912 | raise exc.DBAPIError.instance(None, None, e) |
---|
| 913 | self._reentrant_error = True |
---|
| 914 | try: |
---|
| 915 | if not isinstance(e, self.dialect.dbapi.Error): |
---|
| 916 | return |
---|
| 917 | |
---|
| 918 | if context: |
---|
| 919 | context.handle_dbapi_exception(e) |
---|
| 920 | |
---|
| 921 | is_disconnect = self.dialect.is_disconnect(e) |
---|
| 922 | if is_disconnect: |
---|
| 923 | self.invalidate(e) |
---|
| 924 | self.engine.dispose() |
---|
| 925 | else: |
---|
| 926 | if cursor: |
---|
| 927 | cursor.close() |
---|
| 928 | self._autorollback() |
---|
| 929 | if self.__close_with_result: |
---|
| 930 | self.close() |
---|
| 931 | raise exc.DBAPIError.instance(statement, parameters, e, connection_invalidated=is_disconnect) |
---|
| 932 | finally: |
---|
| 933 | del self._reentrant_error |
---|
| 934 | |
---|
| 935 | def __create_execution_context(self, **kwargs): |
---|
| 936 | try: |
---|
| 937 | dialect = self.engine.dialect |
---|
| 938 | return dialect.execution_ctx_cls(dialect, connection=self, **kwargs) |
---|
| 939 | except Exception, e: |
---|
| 940 | self._handle_dbapi_exception(e, kwargs.get('statement', None), kwargs.get('parameters', None), None, None) |
---|
| 941 | raise |
---|
| 942 | |
---|
| 943 | def _cursor_execute(self, cursor, statement, parameters, context=None): |
---|
| 944 | if self.engine._should_log_info: |
---|
| 945 | self.engine.logger.info(statement) |
---|
| 946 | self.engine.logger.info(repr(parameters)) |
---|
| 947 | try: |
---|
| 948 | self.dialect.do_execute(cursor, statement, parameters, context=context) |
---|
| 949 | except Exception, e: |
---|
| 950 | self._handle_dbapi_exception(e, statement, parameters, cursor, context) |
---|
| 951 | raise |
---|
| 952 | |
---|
| 953 | def _cursor_executemany(self, cursor, statement, parameters, context=None): |
---|
| 954 | if self.engine._should_log_info: |
---|
| 955 | self.engine.logger.info(statement) |
---|
| 956 | self.engine.logger.info(repr(parameters)) |
---|
| 957 | try: |
---|
| 958 | self.dialect.do_executemany(cursor, statement, parameters, context=context) |
---|
| 959 | except Exception, e: |
---|
| 960 | self._handle_dbapi_exception(e, statement, parameters, cursor, context) |
---|
| 961 | raise |
---|
| 962 | |
---|
| 963 | # poor man's multimethod/generic function thingy |
---|
| 964 | executors = { |
---|
| 965 | expression.Function: _execute_function, |
---|
| 966 | expression.ClauseElement: _execute_clauseelement, |
---|
| 967 | Compiled: _execute_compiled, |
---|
| 968 | schema.SchemaItem: _execute_default, |
---|
| 969 | schema.DDL: _execute_ddl, |
---|
| 970 | basestring: _execute_text |
---|
| 971 | } |
---|
| 972 | |
---|
| 973 | def create(self, entity, **kwargs): |
---|
| 974 | """Create a Table or Index given an appropriate Schema object.""" |
---|
| 975 | |
---|
| 976 | return self.engine.create(entity, connection=self, **kwargs) |
---|
| 977 | |
---|
| 978 | def drop(self, entity, **kwargs): |
---|
| 979 | """Drop a Table or Index given an appropriate Schema object.""" |
---|
| 980 | |
---|
| 981 | return self.engine.drop(entity, connection=self, **kwargs) |
---|
| 982 | |
---|
| 983 | def reflecttable(self, table, include_columns=None): |
---|
| 984 | """Reflect the columns in the given string table name from the database.""" |
---|
| 985 | |
---|
| 986 | return self.engine.reflecttable(table, self, include_columns) |
---|
| 987 | |
---|
| 988 | def default_schema_name(self): |
---|
| 989 | return self.engine.dialect.get_default_schema_name(self) |
---|
| 990 | |
---|
| 991 | def run_callable(self, callable_): |
---|
| 992 | return callable_(self) |
---|
| 993 | |
---|
| 994 | class Transaction(object): |
---|
| 995 | """Represent a Transaction in progress. |
---|
| 996 | |
---|
| 997 | The Transaction object is **not** threadsafe. |
---|
| 998 | |
---|
| 999 | .. index:: |
---|
| 1000 | single: thread safety; Transaction |
---|
| 1001 | |
---|
| 1002 | """ |
---|
| 1003 | |
---|
| 1004 | def __init__(self, connection, parent): |
---|
| 1005 | self.connection = connection |
---|
| 1006 | self._parent = parent or self |
---|
| 1007 | self.is_active = True |
---|
| 1008 | |
---|
| 1009 | def close(self): |
---|
| 1010 | """Close this transaction. |
---|
| 1011 | |
---|
| 1012 | If this transaction is the base transaction in a begin/commit |
---|
| 1013 | nesting, the transaction will rollback(). Otherwise, the |
---|
| 1014 | method returns. |
---|
| 1015 | |
---|
| 1016 | This is used to cancel a Transaction without affecting the scope of |
---|
| 1017 | an enclosing transaction. |
---|
| 1018 | """ |
---|
| 1019 | if not self._parent.is_active: |
---|
| 1020 | return |
---|
| 1021 | if self._parent is self: |
---|
| 1022 | self.rollback() |
---|
| 1023 | |
---|
| 1024 | def rollback(self): |
---|
| 1025 | if not self._parent.is_active: |
---|
| 1026 | return |
---|
| 1027 | self.is_active = False |
---|
| 1028 | self._do_rollback() |
---|
| 1029 | |
---|
| 1030 | def _do_rollback(self): |
---|
| 1031 | self._parent.rollback() |
---|
| 1032 | |
---|
| 1033 | def commit(self): |
---|
| 1034 | if not self._parent.is_active: |
---|
| 1035 | raise exc.InvalidRequestError("This transaction is inactive") |
---|
| 1036 | self._do_commit() |
---|
| 1037 | self.is_active = False |
---|
| 1038 | |
---|
| 1039 | def _do_commit(self): |
---|
| 1040 | pass |
---|
| 1041 | |
---|
| 1042 | def __enter__(self): |
---|
| 1043 | return self |
---|
| 1044 | |
---|
| 1045 | def __exit__(self, type, value, traceback): |
---|
| 1046 | if type is None and self.is_active: |
---|
| 1047 | self.commit() |
---|
| 1048 | else: |
---|
| 1049 | self.rollback() |
---|
| 1050 | |
---|
| 1051 | class RootTransaction(Transaction): |
---|
| 1052 | def __init__(self, connection): |
---|
| 1053 | super(RootTransaction, self).__init__(connection, None) |
---|
| 1054 | self.connection._begin_impl() |
---|
| 1055 | |
---|
| 1056 | def _do_rollback(self): |
---|
| 1057 | self.connection._rollback_impl() |
---|
| 1058 | |
---|
| 1059 | def _do_commit(self): |
---|
| 1060 | self.connection._commit_impl() |
---|
| 1061 | |
---|
| 1062 | class NestedTransaction(Transaction): |
---|
| 1063 | def __init__(self, connection, parent): |
---|
| 1064 | super(NestedTransaction, self).__init__(connection, parent) |
---|
| 1065 | self._savepoint = self.connection._savepoint_impl() |
---|
| 1066 | |
---|
| 1067 | def _do_rollback(self): |
---|
| 1068 | self.connection._rollback_to_savepoint_impl(self._savepoint, self._parent) |
---|
| 1069 | |
---|
| 1070 | def _do_commit(self): |
---|
| 1071 | self.connection._release_savepoint_impl(self._savepoint, self._parent) |
---|
| 1072 | |
---|
| 1073 | class TwoPhaseTransaction(Transaction): |
---|
| 1074 | def __init__(self, connection, xid): |
---|
| 1075 | super(TwoPhaseTransaction, self).__init__(connection, None) |
---|
| 1076 | self._is_prepared = False |
---|
| 1077 | self.xid = xid |
---|
| 1078 | self.connection._begin_twophase_impl(self.xid) |
---|
| 1079 | |
---|
| 1080 | def prepare(self): |
---|
| 1081 | if not self._parent.is_active: |
---|
| 1082 | raise exc.InvalidRequestError("This transaction is inactive") |
---|
| 1083 | self.connection._prepare_twophase_impl(self.xid) |
---|
| 1084 | self._is_prepared = True |
---|
| 1085 | |
---|
| 1086 | def _do_rollback(self): |
---|
| 1087 | self.connection._rollback_twophase_impl(self.xid, self._is_prepared) |
---|
| 1088 | |
---|
| 1089 | def _do_commit(self): |
---|
| 1090 | self.connection._commit_twophase_impl(self.xid, self._is_prepared) |
---|
| 1091 | |
---|
| 1092 | class Engine(Connectable): |
---|
| 1093 | """ |
---|
| 1094 | Connects a :class:`~sqlalchemy.pool.Pool` and :class:`~sqlalchemy.engine.base.Dialect` |
---|
| 1095 | together to provide a source of database connectivity and behavior. |
---|
| 1096 | |
---|
| 1097 | """ |
---|
| 1098 | |
---|
| 1099 | def __init__(self, pool, dialect, url, echo=None, proxy=None): |
---|
| 1100 | self.pool = pool |
---|
| 1101 | self.url = url |
---|
| 1102 | self.dialect = dialect |
---|
| 1103 | self.echo = echo |
---|
| 1104 | self.engine = self |
---|
| 1105 | self.logger = log.instance_logger(self, echoflag=echo) |
---|
| 1106 | if proxy: |
---|
| 1107 | self.Connection = _proxy_connection_cls(Connection, proxy) |
---|
| 1108 | else: |
---|
| 1109 | self.Connection = Connection |
---|
| 1110 | |
---|
| 1111 | @property |
---|
| 1112 | def name(self): |
---|
| 1113 | "String name of the :class:`~sqlalchemy.engine.Dialect` in use by this ``Engine``." |
---|
| 1114 | |
---|
| 1115 | return self.dialect.name |
---|
| 1116 | |
---|
| 1117 | echo = log.echo_property() |
---|
| 1118 | |
---|
| 1119 | def __repr__(self): |
---|
| 1120 | return 'Engine(%s)' % str(self.url) |
---|
| 1121 | |
---|
| 1122 | def dispose(self): |
---|
| 1123 | self.pool.dispose() |
---|
| 1124 | self.pool = self.pool.recreate() |
---|
| 1125 | |
---|
| 1126 | def create(self, entity, connection=None, **kwargs): |
---|
| 1127 | """Create a table or index within this engine's database connection given a schema.Table object.""" |
---|
| 1128 | |
---|
| 1129 | self._run_visitor(self.dialect.schemagenerator, entity, connection=connection, **kwargs) |
---|
| 1130 | |
---|
| 1131 | def drop(self, entity, connection=None, **kwargs): |
---|
| 1132 | """Drop a table or index within this engine's database connection given a schema.Table object.""" |
---|
| 1133 | |
---|
| 1134 | self._run_visitor(self.dialect.schemadropper, entity, connection=connection, **kwargs) |
---|
| 1135 | |
---|
| 1136 | def _execute_default(self, default): |
---|
| 1137 | connection = self.contextual_connect() |
---|
| 1138 | try: |
---|
| 1139 | return connection._execute_default(default, (), {}) |
---|
| 1140 | finally: |
---|
| 1141 | connection.close() |
---|
| 1142 | |
---|
| 1143 | @property |
---|
| 1144 | def func(self): |
---|
| 1145 | return expression._FunctionGenerator(bind=self) |
---|
| 1146 | |
---|
| 1147 | def text(self, text, *args, **kwargs): |
---|
| 1148 | """Return a sql.text() object for performing literal queries.""" |
---|
| 1149 | |
---|
| 1150 | return expression.text(text, bind=self, *args, **kwargs) |
---|
| 1151 | |
---|
| 1152 | def _run_visitor(self, visitorcallable, element, connection=None, **kwargs): |
---|
| 1153 | if connection is None: |
---|
| 1154 | conn = self.contextual_connect(close_with_result=False) |
---|
| 1155 | else: |
---|
| 1156 | conn = connection |
---|
| 1157 | try: |
---|
| 1158 | visitorcallable(self.dialect, conn, **kwargs).traverse(element) |
---|
| 1159 | finally: |
---|
| 1160 | if connection is None: |
---|
| 1161 | conn.close() |
---|
| 1162 | |
---|
| 1163 | def transaction(self, callable_, connection=None, *args, **kwargs): |
---|
| 1164 | """Execute the given function within a transaction boundary. |
---|
| 1165 | |
---|
| 1166 | This is a shortcut for explicitly calling `begin()` and `commit()` |
---|
| 1167 | and optionally `rollback()` when exceptions are raised. The |
---|
| 1168 | given `*args` and `**kwargs` will be passed to the function, as |
---|
| 1169 | well as the Connection used in the transaction. |
---|
| 1170 | """ |
---|
| 1171 | |
---|
| 1172 | if connection is None: |
---|
| 1173 | conn = self.contextual_connect() |
---|
| 1174 | else: |
---|
| 1175 | conn = connection |
---|
| 1176 | try: |
---|
| 1177 | trans = conn.begin() |
---|
| 1178 | try: |
---|
| 1179 | ret = callable_(conn, *args, **kwargs) |
---|
| 1180 | trans.commit() |
---|
| 1181 | return ret |
---|
| 1182 | except: |
---|
| 1183 | trans.rollback() |
---|
| 1184 | raise |
---|
| 1185 | finally: |
---|
| 1186 | if connection is None: |
---|
| 1187 | conn.close() |
---|
| 1188 | |
---|
| 1189 | def run_callable(self, callable_, connection=None, *args, **kwargs): |
---|
| 1190 | if connection is None: |
---|
| 1191 | conn = self.contextual_connect() |
---|
| 1192 | else: |
---|
| 1193 | conn = connection |
---|
| 1194 | try: |
---|
| 1195 | return callable_(conn, *args, **kwargs) |
---|
| 1196 | finally: |
---|
| 1197 | if connection is None: |
---|
| 1198 | conn.close() |
---|
| 1199 | |
---|
| 1200 | def execute(self, statement, *multiparams, **params): |
---|
| 1201 | connection = self.contextual_connect(close_with_result=True) |
---|
| 1202 | return connection.execute(statement, *multiparams, **params) |
---|
| 1203 | |
---|
| 1204 | def scalar(self, statement, *multiparams, **params): |
---|
| 1205 | return self.execute(statement, *multiparams, **params).scalar() |
---|
| 1206 | |
---|
| 1207 | def _execute_clauseelement(self, elem, multiparams=None, params=None): |
---|
| 1208 | connection = self.contextual_connect(close_with_result=True) |
---|
| 1209 | return connection._execute_clauseelement(elem, multiparams, params) |
---|
| 1210 | |
---|
| 1211 | def _execute_compiled(self, compiled, multiparams, params): |
---|
| 1212 | connection = self.contextual_connect(close_with_result=True) |
---|
| 1213 | return connection._execute_compiled(compiled, multiparams, params) |
---|
| 1214 | |
---|
| 1215 | def statement_compiler(self, statement, **kwargs): |
---|
| 1216 | return self.dialect.statement_compiler(self.dialect, statement, bind=self, **kwargs) |
---|
| 1217 | |
---|
| 1218 | def connect(self, **kwargs): |
---|
| 1219 | """Return a newly allocated Connection object.""" |
---|
| 1220 | |
---|
| 1221 | return self.Connection(self, **kwargs) |
---|
| 1222 | |
---|
| 1223 | def contextual_connect(self, close_with_result=False, **kwargs): |
---|
| 1224 | """Return a Connection object which may be newly allocated, or may be part of some ongoing context. |
---|
| 1225 | |
---|
| 1226 | This Connection is meant to be used by the various "auto-connecting" operations. |
---|
| 1227 | """ |
---|
| 1228 | |
---|
| 1229 | return self.Connection(self, self.pool.connect(), close_with_result=close_with_result, **kwargs) |
---|
| 1230 | |
---|
| 1231 | def table_names(self, schema=None, connection=None): |
---|
| 1232 | """Return a list of all table names available in the database. |
---|
| 1233 | |
---|
| 1234 | schema: |
---|
| 1235 | Optional, retrieve names from a non-default schema. |
---|
| 1236 | |
---|
| 1237 | connection: |
---|
| 1238 | Optional, use a specified connection. Default is the |
---|
| 1239 | ``contextual_connect`` for this ``Engine``. |
---|
| 1240 | """ |
---|
| 1241 | |
---|
| 1242 | if connection is None: |
---|
| 1243 | conn = self.contextual_connect() |
---|
| 1244 | else: |
---|
| 1245 | conn = connection |
---|
| 1246 | if not schema: |
---|
| 1247 | try: |
---|
| 1248 | schema = self.dialect.get_default_schema_name(conn) |
---|
| 1249 | except NotImplementedError: |
---|
| 1250 | pass |
---|
| 1251 | try: |
---|
| 1252 | return self.dialect.table_names(conn, schema) |
---|
| 1253 | finally: |
---|
| 1254 | if connection is None: |
---|
| 1255 | conn.close() |
---|
| 1256 | |
---|
| 1257 | def reflecttable(self, table, connection=None, include_columns=None): |
---|
| 1258 | """Given a Table object, reflects its columns and properties from the database.""" |
---|
| 1259 | |
---|
| 1260 | if connection is None: |
---|
| 1261 | conn = self.contextual_connect() |
---|
| 1262 | else: |
---|
| 1263 | conn = connection |
---|
| 1264 | try: |
---|
| 1265 | self.dialect.reflecttable(conn, table, include_columns) |
---|
| 1266 | finally: |
---|
| 1267 | if connection is None: |
---|
| 1268 | conn.close() |
---|
| 1269 | |
---|
| 1270 | def has_table(self, table_name, schema=None): |
---|
| 1271 | return self.run_callable(lambda c: self.dialect.has_table(c, table_name, schema=schema)) |
---|
| 1272 | |
---|
| 1273 | def raw_connection(self): |
---|
| 1274 | """Return a DB-API connection.""" |
---|
| 1275 | |
---|
| 1276 | return self.pool.unique_connection() |
---|
| 1277 | |
---|
| 1278 | def _proxy_connection_cls(cls, proxy): |
---|
| 1279 | class ProxyConnection(cls): |
---|
| 1280 | def execute(self, object, *multiparams, **params): |
---|
| 1281 | return proxy.execute(self, super(ProxyConnection, self).execute, object, *multiparams, **params) |
---|
| 1282 | |
---|
| 1283 | def _execute_clauseelement(self, elem, multiparams=None, params=None): |
---|
| 1284 | return proxy.execute(self, super(ProxyConnection, self).execute, elem, *(multiparams or []), **(params or {})) |
---|
| 1285 | |
---|
| 1286 | def _cursor_execute(self, cursor, statement, parameters, context=None): |
---|
| 1287 | return proxy.cursor_execute(super(ProxyConnection, self)._cursor_execute, cursor, statement, parameters, context, False) |
---|
| 1288 | |
---|
| 1289 | def _cursor_executemany(self, cursor, statement, parameters, context=None): |
---|
| 1290 | return proxy.cursor_execute(super(ProxyConnection, self)._cursor_executemany, cursor, statement, parameters, context, True) |
---|
| 1291 | |
---|
| 1292 | return ProxyConnection |
---|
| 1293 | |
---|
| 1294 | class RowProxy(object): |
---|
| 1295 | """Proxy a single cursor row for a parent ResultProxy. |
---|
| 1296 | |
---|
| 1297 | Mostly follows "ordered dictionary" behavior, mapping result |
---|
| 1298 | values to the string-based column name, the integer position of |
---|
| 1299 | the result in the row, as well as Column instances which can be |
---|
| 1300 | mapped to the original Columns that produced this result set (for |
---|
| 1301 | results that correspond to constructed SQL expressions). |
---|
| 1302 | """ |
---|
| 1303 | |
---|
| 1304 | __slots__ = ['__parent', '__row'] |
---|
| 1305 | |
---|
| 1306 | def __init__(self, parent, row): |
---|
| 1307 | """RowProxy objects are constructed by ResultProxy objects.""" |
---|
| 1308 | |
---|
| 1309 | self.__parent = parent |
---|
| 1310 | self.__row = row |
---|
| 1311 | if self.__parent._echo: |
---|
| 1312 | self.__parent.context.engine.logger.debug("Row " + repr(row)) |
---|
| 1313 | |
---|
| 1314 | def close(self): |
---|
| 1315 | """Close the parent ResultProxy.""" |
---|
| 1316 | |
---|
| 1317 | self.__parent.close() |
---|
| 1318 | |
---|
| 1319 | def __contains__(self, key): |
---|
| 1320 | return self.__parent._has_key(self.__row, key) |
---|
| 1321 | |
---|
| 1322 | def __len__(self): |
---|
| 1323 | return len(self.__row) |
---|
| 1324 | |
---|
| 1325 | def __iter__(self): |
---|
| 1326 | for i in xrange(len(self.__row)): |
---|
| 1327 | yield self.__parent._get_col(self.__row, i) |
---|
| 1328 | |
---|
| 1329 | __hash__ = None |
---|
| 1330 | |
---|
| 1331 | def __eq__(self, other): |
---|
| 1332 | return ((other is self) or |
---|
| 1333 | (other == tuple(self.__parent._get_col(self.__row, key) |
---|
| 1334 | for key in xrange(len(self.__row))))) |
---|
| 1335 | |
---|
| 1336 | def __ne__(self, other): |
---|
| 1337 | return not self.__eq__(other) |
---|
| 1338 | |
---|
| 1339 | def __repr__(self): |
---|
| 1340 | return repr(tuple(self)) |
---|
| 1341 | |
---|
| 1342 | def has_key(self, key): |
---|
| 1343 | """Return True if this RowProxy contains the given key.""" |
---|
| 1344 | |
---|
| 1345 | return self.__parent._has_key(self.__row, key) |
---|
| 1346 | |
---|
| 1347 | def __getitem__(self, key): |
---|
| 1348 | return self.__parent._get_col(self.__row, key) |
---|
| 1349 | |
---|
| 1350 | def __getattr__(self, name): |
---|
| 1351 | try: |
---|
| 1352 | return self.__parent._get_col(self.__row, name) |
---|
| 1353 | except KeyError, e: |
---|
| 1354 | raise AttributeError(e.args[0]) |
---|
| 1355 | |
---|
| 1356 | def items(self): |
---|
| 1357 | """Return a list of tuples, each tuple containing a key/value pair.""" |
---|
| 1358 | |
---|
| 1359 | return [(key, getattr(self, key)) for key in self.iterkeys()] |
---|
| 1360 | |
---|
| 1361 | def keys(self): |
---|
| 1362 | """Return the list of keys as strings represented by this RowProxy.""" |
---|
| 1363 | |
---|
| 1364 | return self.__parent.keys |
---|
| 1365 | |
---|
| 1366 | def iterkeys(self): |
---|
| 1367 | return iter(self.__parent.keys) |
---|
| 1368 | |
---|
| 1369 | def values(self): |
---|
| 1370 | """Return the values represented by this RowProxy as a list.""" |
---|
| 1371 | |
---|
| 1372 | return list(self) |
---|
| 1373 | |
---|
| 1374 | def itervalues(self): |
---|
| 1375 | return iter(self) |
---|
| 1376 | |
---|
| 1377 | class BufferedColumnRow(RowProxy): |
---|
| 1378 | def __init__(self, parent, row): |
---|
| 1379 | row = [ResultProxy._get_col(parent, row, i) for i in xrange(len(row))] |
---|
| 1380 | super(BufferedColumnRow, self).__init__(parent, row) |
---|
| 1381 | |
---|
| 1382 | |
---|
| 1383 | class ResultProxy(object): |
---|
| 1384 | """Wraps a DB-API cursor object to provide easier access to row columns. |
---|
| 1385 | |
---|
| 1386 | Individual columns may be accessed by their integer position, |
---|
| 1387 | case-insensitive column name, or by ``schema.Column`` |
---|
| 1388 | object. e.g.:: |
---|
| 1389 | |
---|
| 1390 | row = fetchone() |
---|
| 1391 | |
---|
| 1392 | col1 = row[0] # access via integer position |
---|
| 1393 | |
---|
| 1394 | col2 = row['col2'] # access via name |
---|
| 1395 | |
---|
| 1396 | col3 = row[mytable.c.mycol] # access via Column object. |
---|
| 1397 | |
---|
| 1398 | ResultProxy also contains a map of TypeEngine objects and will |
---|
| 1399 | invoke the appropriate ``result_processor()`` method before |
---|
| 1400 | returning columns, as well as the ExecutionContext corresponding |
---|
| 1401 | to the statement execution. It provides several methods for which |
---|
| 1402 | to obtain information from the underlying ExecutionContext. |
---|
| 1403 | """ |
---|
| 1404 | |
---|
| 1405 | _process_row = RowProxy |
---|
| 1406 | |
---|
| 1407 | def __init__(self, context): |
---|
| 1408 | """ResultProxy objects are constructed via the execute() method on SQLEngine.""" |
---|
| 1409 | self.context = context |
---|
| 1410 | self.dialect = context.dialect |
---|
| 1411 | self.closed = False |
---|
| 1412 | self.cursor = context.cursor |
---|
| 1413 | self.connection = context.root_connection |
---|
| 1414 | self._echo = context.engine._should_log_info |
---|
| 1415 | self._init_metadata() |
---|
| 1416 | |
---|
| 1417 | @property |
---|
| 1418 | def rowcount(self): |
---|
| 1419 | if self._rowcount is None: |
---|
| 1420 | return self.context.get_rowcount() |
---|
| 1421 | else: |
---|
| 1422 | return self._rowcount |
---|
| 1423 | |
---|
| 1424 | @property |
---|
| 1425 | def lastrowid(self): |
---|
| 1426 | return self.cursor.lastrowid |
---|
| 1427 | |
---|
| 1428 | @property |
---|
| 1429 | def out_parameters(self): |
---|
| 1430 | return self.context.out_parameters |
---|
| 1431 | |
---|
| 1432 | def _init_metadata(self): |
---|
| 1433 | metadata = self.cursor.description |
---|
| 1434 | if metadata is None: |
---|
| 1435 | # no results, get rowcount (which requires open cursor on some DB's such as firebird), |
---|
| 1436 | # then close |
---|
| 1437 | self._rowcount = self.context.get_rowcount() |
---|
| 1438 | self.close() |
---|
| 1439 | return |
---|
| 1440 | |
---|
| 1441 | self._rowcount = None |
---|
| 1442 | self._props = util.populate_column_dict(None) |
---|
| 1443 | self._props.creator = self.__key_fallback() |
---|
| 1444 | self.keys = [] |
---|
| 1445 | |
---|
| 1446 | typemap = self.dialect.dbapi_type_map |
---|
| 1447 | |
---|
| 1448 | for i, item in enumerate(metadata): |
---|
| 1449 | colname = item[0] |
---|
| 1450 | if self.dialect.description_encoding: |
---|
| 1451 | colname = colname.decode(self.dialect.description_encoding) |
---|
| 1452 | |
---|
| 1453 | if '.' in colname: |
---|
| 1454 | # sqlite will in some circumstances prepend table name to colnames, so strip |
---|
| 1455 | origname = colname |
---|
| 1456 | colname = colname.split('.')[-1] |
---|
| 1457 | else: |
---|
| 1458 | origname = None |
---|
| 1459 | |
---|
| 1460 | if self.context.result_map: |
---|
| 1461 | try: |
---|
| 1462 | (name, obj, type_) = self.context.result_map[colname.lower()] |
---|
| 1463 | except KeyError: |
---|
| 1464 | (name, obj, type_) = (colname, None, typemap.get(item[1], types.NULLTYPE)) |
---|
| 1465 | else: |
---|
| 1466 | (name, obj, type_) = (colname, None, typemap.get(item[1], types.NULLTYPE)) |
---|
| 1467 | |
---|
| 1468 | rec = (type_, type_.dialect_impl(self.dialect).result_processor(self.dialect), i) |
---|
| 1469 | |
---|
| 1470 | if self._props.setdefault(name.lower(), rec) is not rec: |
---|
| 1471 | self._props[name.lower()] = (type_, self.__ambiguous_processor(name), 0) |
---|
| 1472 | |
---|
| 1473 | # store the "origname" if we truncated (sqlite only) |
---|
| 1474 | if origname: |
---|
| 1475 | if self._props.setdefault(origname.lower(), rec) is not rec: |
---|
| 1476 | self._props[origname.lower()] = (type_, self.__ambiguous_processor(origname), 0) |
---|
| 1477 | |
---|
| 1478 | self.keys.append(colname) |
---|
| 1479 | self._props[i] = rec |
---|
| 1480 | if obj: |
---|
| 1481 | for o in obj: |
---|
| 1482 | self._props[o] = rec |
---|
| 1483 | |
---|
| 1484 | if self._echo: |
---|
| 1485 | self.context.engine.logger.debug( |
---|
| 1486 | "Col " + repr(tuple(x[0] for x in metadata))) |
---|
| 1487 | |
---|
| 1488 | def __key_fallback(self): |
---|
| 1489 | # create a closure without 'self' to avoid circular references |
---|
| 1490 | props = self._props |
---|
| 1491 | |
---|
| 1492 | def fallback(key): |
---|
| 1493 | if isinstance(key, basestring): |
---|
| 1494 | key = key.lower() |
---|
| 1495 | if key in props: |
---|
| 1496 | return props[key] |
---|
| 1497 | |
---|
| 1498 | # fallback for targeting a ColumnElement to a textual expression |
---|
| 1499 | # this is a rare use case which only occurs when matching text() |
---|
| 1500 | # constructs to ColumnElements |
---|
| 1501 | if isinstance(key, expression.ColumnElement): |
---|
| 1502 | if key._label and key._label.lower() in props: |
---|
| 1503 | return props[key._label.lower()] |
---|
| 1504 | elif hasattr(key, 'name') and key.name.lower() in props: |
---|
| 1505 | return props[key.name.lower()] |
---|
| 1506 | |
---|
| 1507 | raise exc.NoSuchColumnError("Could not locate column in row for column '%s'" % (str(key))) |
---|
| 1508 | return fallback |
---|
| 1509 | |
---|
| 1510 | def __ambiguous_processor(self, colname): |
---|
| 1511 | def process(value): |
---|
| 1512 | raise exc.InvalidRequestError("Ambiguous column name '%s' in result set! " |
---|
| 1513 | "try 'use_labels' option on select statement." % colname) |
---|
| 1514 | return process |
---|
| 1515 | |
---|
| 1516 | def close(self): |
---|
| 1517 | """Close this ResultProxy. |
---|
| 1518 | |
---|
| 1519 | Closes the underlying DBAPI cursor corresponding to the execution. |
---|
| 1520 | |
---|
| 1521 | If this ResultProxy was generated from an implicit execution, |
---|
| 1522 | the underlying Connection will also be closed (returns the |
---|
| 1523 | underlying DBAPI connection to the connection pool.) |
---|
| 1524 | |
---|
| 1525 | This method is called automatically when: |
---|
| 1526 | |
---|
| 1527 | * all result rows are exhausted using the fetchXXX() methods. |
---|
| 1528 | * cursor.description is None. |
---|
| 1529 | |
---|
| 1530 | """ |
---|
| 1531 | if not self.closed: |
---|
| 1532 | self.closed = True |
---|
| 1533 | self.cursor.close() |
---|
| 1534 | if self.connection.should_close_with_result: |
---|
| 1535 | self.connection.close() |
---|
| 1536 | |
---|
| 1537 | def _has_key(self, row, key): |
---|
| 1538 | try: |
---|
| 1539 | # _key_cache uses __missing__ in 2.5, so not much alternative |
---|
| 1540 | # to catching KeyError |
---|
| 1541 | self._props[key] |
---|
| 1542 | return True |
---|
| 1543 | except KeyError: |
---|
| 1544 | return False |
---|
| 1545 | |
---|
| 1546 | def __iter__(self): |
---|
| 1547 | while True: |
---|
| 1548 | row = self.fetchone() |
---|
| 1549 | if row is None: |
---|
| 1550 | raise StopIteration |
---|
| 1551 | else: |
---|
| 1552 | yield row |
---|
| 1553 | |
---|
| 1554 | def last_inserted_ids(self): |
---|
| 1555 | """Return ``last_inserted_ids()`` from the underlying ExecutionContext. |
---|
| 1556 | |
---|
| 1557 | See ExecutionContext for details. |
---|
| 1558 | |
---|
| 1559 | """ |
---|
| 1560 | return self.context.last_inserted_ids() |
---|
| 1561 | |
---|
| 1562 | def last_updated_params(self): |
---|
| 1563 | """Return ``last_updated_params()`` from the underlying ExecutionContext. |
---|
| 1564 | |
---|
| 1565 | See ExecutionContext for details. |
---|
| 1566 | |
---|
| 1567 | """ |
---|
| 1568 | return self.context.last_updated_params() |
---|
| 1569 | |
---|
| 1570 | def last_inserted_params(self): |
---|
| 1571 | """Return ``last_inserted_params()`` from the underlying ExecutionContext. |
---|
| 1572 | |
---|
| 1573 | See ExecutionContext for details. |
---|
| 1574 | |
---|
| 1575 | """ |
---|
| 1576 | return self.context.last_inserted_params() |
---|
| 1577 | |
---|
| 1578 | def lastrow_has_defaults(self): |
---|
| 1579 | """Return ``lastrow_has_defaults()`` from the underlying ExecutionContext. |
---|
| 1580 | |
---|
| 1581 | See ExecutionContext for details. |
---|
| 1582 | |
---|
| 1583 | """ |
---|
| 1584 | return self.context.lastrow_has_defaults() |
---|
| 1585 | |
---|
| 1586 | def postfetch_cols(self): |
---|
| 1587 | """Return ``postfetch_cols()`` from the underlying ExecutionContext. |
---|
| 1588 | |
---|
| 1589 | See ExecutionContext for details. |
---|
| 1590 | |
---|
| 1591 | """ |
---|
| 1592 | return self.context.postfetch_cols |
---|
| 1593 | |
---|
| 1594 | def prefetch_cols(self): |
---|
| 1595 | return self.context.prefetch_cols |
---|
| 1596 | |
---|
| 1597 | def supports_sane_rowcount(self): |
---|
| 1598 | """Return ``supports_sane_rowcount`` from the dialect.""" |
---|
| 1599 | |
---|
| 1600 | return self.dialect.supports_sane_rowcount |
---|
| 1601 | |
---|
| 1602 | def supports_sane_multi_rowcount(self): |
---|
| 1603 | """Return ``supports_sane_multi_rowcount`` from the dialect.""" |
---|
| 1604 | |
---|
| 1605 | return self.dialect.supports_sane_multi_rowcount |
---|
| 1606 | |
---|
| 1607 | def _get_col(self, row, key): |
---|
| 1608 | try: |
---|
| 1609 | type_, processor, index = self._props[key] |
---|
| 1610 | except TypeError: |
---|
| 1611 | # the 'slice' use case is very infrequent, |
---|
| 1612 | # so we use an exception catch to reduce conditionals in _get_col |
---|
| 1613 | if isinstance(key, slice): |
---|
| 1614 | indices = key.indices(len(row)) |
---|
| 1615 | return tuple(self._get_col(row, i) for i in xrange(*indices)) |
---|
| 1616 | else: |
---|
| 1617 | raise |
---|
| 1618 | |
---|
| 1619 | if processor: |
---|
| 1620 | return processor(row[index]) |
---|
| 1621 | else: |
---|
| 1622 | return row[index] |
---|
| 1623 | |
---|
| 1624 | def _fetchone_impl(self): |
---|
| 1625 | return self.cursor.fetchone() |
---|
| 1626 | |
---|
| 1627 | def _fetchmany_impl(self, size=None): |
---|
| 1628 | return self.cursor.fetchmany(size) |
---|
| 1629 | |
---|
| 1630 | def _fetchall_impl(self): |
---|
| 1631 | return self.cursor.fetchall() |
---|
| 1632 | |
---|
| 1633 | def fetchall(self): |
---|
| 1634 | """Fetch all rows, just like DB-API ``cursor.fetchall()``.""" |
---|
| 1635 | |
---|
| 1636 | try: |
---|
| 1637 | process_row = self._process_row |
---|
| 1638 | l = [process_row(self, row) for row in self._fetchall_impl()] |
---|
| 1639 | self.close() |
---|
| 1640 | return l |
---|
| 1641 | except Exception, e: |
---|
| 1642 | self.connection._handle_dbapi_exception(e, None, None, self.cursor, self.context) |
---|
| 1643 | raise |
---|
| 1644 | |
---|
| 1645 | def fetchmany(self, size=None): |
---|
| 1646 | """Fetch many rows, just like DB-API ``cursor.fetchmany(size=cursor.arraysize)``.""" |
---|
| 1647 | |
---|
| 1648 | try: |
---|
| 1649 | process_row = self._process_row |
---|
| 1650 | l = [process_row(self, row) for row in self._fetchmany_impl(size)] |
---|
| 1651 | if len(l) == 0: |
---|
| 1652 | self.close() |
---|
| 1653 | return l |
---|
| 1654 | except Exception, e: |
---|
| 1655 | self.connection._handle_dbapi_exception(e, None, None, self.cursor, self.context) |
---|
| 1656 | raise |
---|
| 1657 | |
---|
| 1658 | def fetchone(self): |
---|
| 1659 | """Fetch one row, just like DB-API ``cursor.fetchone()``.""" |
---|
| 1660 | try: |
---|
| 1661 | row = self._fetchone_impl() |
---|
| 1662 | if row is not None: |
---|
| 1663 | return self._process_row(self, row) |
---|
| 1664 | else: |
---|
| 1665 | self.close() |
---|
| 1666 | return None |
---|
| 1667 | except Exception, e: |
---|
| 1668 | self.connection._handle_dbapi_exception(e, None, None, self.cursor, self.context) |
---|
| 1669 | raise |
---|
| 1670 | |
---|
| 1671 | def scalar(self): |
---|
| 1672 | """Fetch the first column of the first row, and close the result set.""" |
---|
| 1673 | try: |
---|
| 1674 | row = self._fetchone_impl() |
---|
| 1675 | except Exception, e: |
---|
| 1676 | self.connection._handle_dbapi_exception(e, None, None, self.cursor, self.context) |
---|
| 1677 | raise |
---|
| 1678 | |
---|
| 1679 | try: |
---|
| 1680 | if row is not None: |
---|
| 1681 | return self._process_row(self, row)[0] |
---|
| 1682 | else: |
---|
| 1683 | return None |
---|
| 1684 | finally: |
---|
| 1685 | self.close() |
---|
| 1686 | |
---|
| 1687 | class BufferedRowResultProxy(ResultProxy): |
---|
| 1688 | """A ResultProxy with row buffering behavior. |
---|
| 1689 | |
---|
| 1690 | ``ResultProxy`` that buffers the contents of a selection of rows |
---|
| 1691 | before ``fetchone()`` is called. This is to allow the results of |
---|
| 1692 | ``cursor.description`` to be available immediately, when |
---|
| 1693 | interfacing with a DB-API that requires rows to be consumed before |
---|
| 1694 | this information is available (currently psycopg2, when used with |
---|
| 1695 | server-side cursors). |
---|
| 1696 | |
---|
| 1697 | The pre-fetching behavior fetches only one row initially, and then |
---|
| 1698 | grows its buffer size by a fixed amount with each successive need |
---|
| 1699 | for additional rows up to a size of 100. |
---|
| 1700 | |
---|
| 1701 | """ |
---|
| 1702 | |
---|
| 1703 | def _init_metadata(self): |
---|
| 1704 | self.__buffer_rows() |
---|
| 1705 | super(BufferedRowResultProxy, self)._init_metadata() |
---|
| 1706 | |
---|
| 1707 | # this is a "growth chart" for the buffering of rows. |
---|
| 1708 | # each successive __buffer_rows call will use the next |
---|
| 1709 | # value in the list for the buffer size until the max |
---|
| 1710 | # is reached |
---|
| 1711 | size_growth = { |
---|
| 1712 | 1 : 5, |
---|
| 1713 | 5 : 10, |
---|
| 1714 | 10 : 20, |
---|
| 1715 | 20 : 50, |
---|
| 1716 | 50 : 100 |
---|
| 1717 | } |
---|
| 1718 | |
---|
| 1719 | def __buffer_rows(self): |
---|
| 1720 | size = getattr(self, '_bufsize', 1) |
---|
| 1721 | self.__rowbuffer = self.cursor.fetchmany(size) |
---|
| 1722 | self._bufsize = self.size_growth.get(size, size) |
---|
| 1723 | |
---|
| 1724 | def _fetchone_impl(self): |
---|
| 1725 | if self.closed: |
---|
| 1726 | return None |
---|
| 1727 | if len(self.__rowbuffer) == 0: |
---|
| 1728 | self.__buffer_rows() |
---|
| 1729 | if len(self.__rowbuffer) == 0: |
---|
| 1730 | return None |
---|
| 1731 | return self.__rowbuffer.pop(0) |
---|
| 1732 | |
---|
| 1733 | def _fetchmany_impl(self, size=None): |
---|
| 1734 | result = [] |
---|
| 1735 | for x in range(0, size): |
---|
| 1736 | row = self._fetchone_impl() |
---|
| 1737 | if row is None: |
---|
| 1738 | break |
---|
| 1739 | result.append(row) |
---|
| 1740 | return result |
---|
| 1741 | |
---|
| 1742 | def _fetchall_impl(self): |
---|
| 1743 | return self.__rowbuffer + list(self.cursor.fetchall()) |
---|
| 1744 | |
---|
| 1745 | class BufferedColumnResultProxy(ResultProxy): |
---|
| 1746 | """A ResultProxy with column buffering behavior. |
---|
| 1747 | |
---|
| 1748 | ``ResultProxy`` that loads all columns into memory each time |
---|
| 1749 | fetchone() is called. If fetchmany() or fetchall() are called, |
---|
| 1750 | the full grid of results is fetched. This is to operate with |
---|
| 1751 | databases where result rows contain "live" results that fall out |
---|
| 1752 | of scope unless explicitly fetched. Currently this includes just |
---|
| 1753 | cx_Oracle LOB objects, but this behavior is known to exist in |
---|
| 1754 | other DB-APIs as well (Pygresql, currently unsupported). |
---|
| 1755 | |
---|
| 1756 | """ |
---|
| 1757 | |
---|
| 1758 | _process_row = BufferedColumnRow |
---|
| 1759 | |
---|
| 1760 | def _get_col(self, row, key): |
---|
| 1761 | try: |
---|
| 1762 | rec = self._props[key] |
---|
| 1763 | return row[rec[2]] |
---|
| 1764 | except TypeError: |
---|
| 1765 | # the 'slice' use case is very infrequent, |
---|
| 1766 | # so we use an exception catch to reduce conditionals in _get_col |
---|
| 1767 | if isinstance(key, slice): |
---|
| 1768 | indices = key.indices(len(row)) |
---|
| 1769 | return tuple(self._get_col(row, i) for i in xrange(*indices)) |
---|
| 1770 | else: |
---|
| 1771 | raise |
---|
| 1772 | |
---|
| 1773 | def fetchall(self): |
---|
| 1774 | l = [] |
---|
| 1775 | while True: |
---|
| 1776 | row = self.fetchone() |
---|
| 1777 | if row is None: |
---|
| 1778 | break |
---|
| 1779 | l.append(row) |
---|
| 1780 | return l |
---|
| 1781 | |
---|
| 1782 | def fetchmany(self, size=None): |
---|
| 1783 | if size is None: |
---|
| 1784 | return self.fetchall() |
---|
| 1785 | l = [] |
---|
| 1786 | for i in xrange(size): |
---|
| 1787 | row = self.fetchone() |
---|
| 1788 | if row is None: |
---|
| 1789 | break |
---|
| 1790 | l.append(row) |
---|
| 1791 | return l |
---|
| 1792 | |
---|
| 1793 | |
---|
| 1794 | class SchemaIterator(schema.SchemaVisitor): |
---|
| 1795 | """A visitor that can gather text into a buffer and execute the contents of the buffer.""" |
---|
| 1796 | |
---|
| 1797 | def __init__(self, connection): |
---|
| 1798 | """Construct a new SchemaIterator.""" |
---|
| 1799 | |
---|
| 1800 | self.connection = connection |
---|
| 1801 | self.buffer = StringIO.StringIO() |
---|
| 1802 | |
---|
| 1803 | def append(self, s): |
---|
| 1804 | """Append content to the SchemaIterator's query buffer.""" |
---|
| 1805 | |
---|
| 1806 | self.buffer.write(s) |
---|
| 1807 | |
---|
| 1808 | def execute(self): |
---|
| 1809 | """Execute the contents of the SchemaIterator's buffer.""" |
---|
| 1810 | |
---|
| 1811 | try: |
---|
| 1812 | return self.connection.execute(self.buffer.getvalue()) |
---|
| 1813 | finally: |
---|
| 1814 | self.buffer.truncate(0) |
---|
| 1815 | |
---|
| 1816 | class DefaultRunner(schema.SchemaVisitor): |
---|
| 1817 | """A visitor which accepts ColumnDefault objects, produces the |
---|
| 1818 | dialect-specific SQL corresponding to their execution, and |
---|
| 1819 | executes the SQL, returning the result value. |
---|
| 1820 | |
---|
| 1821 | DefaultRunners are used internally by Engines and Dialects. |
---|
| 1822 | Specific database modules should provide their own subclasses of |
---|
| 1823 | DefaultRunner to allow database-specific behavior. |
---|
| 1824 | |
---|
| 1825 | """ |
---|
| 1826 | |
---|
| 1827 | def __init__(self, context): |
---|
| 1828 | self.context = context |
---|
| 1829 | self.dialect = context.dialect |
---|
| 1830 | self.cursor = context.cursor |
---|
| 1831 | |
---|
| 1832 | def get_column_default(self, column): |
---|
| 1833 | if column.default is not None: |
---|
| 1834 | return self.traverse_single(column.default) |
---|
| 1835 | else: |
---|
| 1836 | return None |
---|
| 1837 | |
---|
| 1838 | def get_column_onupdate(self, column): |
---|
| 1839 | if column.onupdate is not None: |
---|
| 1840 | return self.traverse_single(column.onupdate) |
---|
| 1841 | else: |
---|
| 1842 | return None |
---|
| 1843 | |
---|
| 1844 | def visit_passive_default(self, default): |
---|
| 1845 | return None |
---|
| 1846 | |
---|
| 1847 | def visit_sequence(self, seq): |
---|
| 1848 | return None |
---|
| 1849 | |
---|
| 1850 | def exec_default_sql(self, default): |
---|
| 1851 | conn = self.context.connection |
---|
| 1852 | c = expression.select([default.arg]).compile(bind=conn) |
---|
| 1853 | return conn._execute_compiled(c, (), {}).scalar() |
---|
| 1854 | |
---|
| 1855 | def execute_string(self, stmt, params=None): |
---|
| 1856 | """execute a string statement, using the raw cursor, and return a scalar result.""" |
---|
| 1857 | |
---|
| 1858 | conn = self.context._connection |
---|
| 1859 | if isinstance(stmt, unicode) and not self.dialect.supports_unicode_statements: |
---|
| 1860 | stmt = stmt.encode(self.dialect.encoding) |
---|
| 1861 | conn._cursor_execute(self.cursor, stmt, params) |
---|
| 1862 | return self.cursor.fetchone()[0] |
---|
| 1863 | |
---|
| 1864 | def visit_column_onupdate(self, onupdate): |
---|
| 1865 | if isinstance(onupdate.arg, expression.ClauseElement): |
---|
| 1866 | return self.exec_default_sql(onupdate) |
---|
| 1867 | elif util.callable(onupdate.arg): |
---|
| 1868 | return onupdate.arg(self.context) |
---|
| 1869 | else: |
---|
| 1870 | return onupdate.arg |
---|
| 1871 | |
---|
| 1872 | def visit_column_default(self, default): |
---|
| 1873 | if isinstance(default.arg, expression.ClauseElement): |
---|
| 1874 | return self.exec_default_sql(default) |
---|
| 1875 | elif util.callable(default.arg): |
---|
| 1876 | return default.arg(self.context) |
---|
| 1877 | else: |
---|
| 1878 | return default.arg |
---|
| 1879 | |
---|
| 1880 | |
---|
| 1881 | def connection_memoize(key): |
---|
| 1882 | """Decorator, memoize a function in a connection.info stash. |
---|
| 1883 | |
---|
| 1884 | Only applicable to functions which take no arguments other than a |
---|
| 1885 | connection. The memo will be stored in ``connection.info[key]``. |
---|
| 1886 | |
---|
| 1887 | """ |
---|
| 1888 | @util.decorator |
---|
| 1889 | def decorated(fn, self, connection): |
---|
| 1890 | connection = connection.connect() |
---|
| 1891 | try: |
---|
| 1892 | return connection.info[key] |
---|
| 1893 | except KeyError: |
---|
| 1894 | connection.info[key] = val = fn(self, connection) |
---|
| 1895 | return val |
---|
| 1896 | |
---|
| 1897 | return decorated |
---|