[3] | 1 | """ |
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| 2 | Database schema version management. |
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| 3 | """ |
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| 4 | from sqlalchemy import (Table, Column, MetaData, String, Text, Integer, |
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| 5 | create_engine) |
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| 6 | from sqlalchemy.sql import and_ |
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| 7 | from sqlalchemy import exceptions as sa_exceptions |
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| 8 | |
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| 9 | from migrate.versioning import exceptions, genmodel, schemadiff |
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| 10 | from migrate.versioning.repository import Repository |
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| 11 | from migrate.versioning.util import load_model |
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| 12 | from migrate.versioning.version import VerNum |
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| 13 | |
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| 14 | |
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| 15 | class ControlledSchema(object): |
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| 16 | """A database under version control""" |
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| 17 | |
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| 18 | def __init__(self, engine, repository): |
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| 19 | if isinstance(repository, str): |
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| 20 | repository=Repository(repository) |
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| 21 | self.engine = engine |
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| 22 | self.repository = repository |
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| 23 | self.meta=MetaData(engine) |
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| 24 | self._load() |
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| 25 | |
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| 26 | def __eq__(self, other): |
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| 27 | return (self.repository is other.repository \ |
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| 28 | and self.version == other.version) |
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| 29 | |
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| 30 | def _load(self): |
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| 31 | """Load controlled schema version info from DB""" |
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| 32 | tname = self.repository.version_table |
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| 33 | self.meta=MetaData(self.engine) |
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| 34 | if not hasattr(self, 'table') or self.table is None: |
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| 35 | try: |
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| 36 | self.table = Table(tname, self.meta, autoload=True) |
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| 37 | except (exceptions.NoSuchTableError): |
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| 38 | raise exceptions.DatabaseNotControlledError(tname) |
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| 39 | # TODO?: verify that the table is correct (# cols, etc.) |
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| 40 | result = self.engine.execute(self.table.select( |
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| 41 | self.table.c.repository_id == str(self.repository.id))) |
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| 42 | data = list(result)[0] |
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| 43 | # TODO?: exception if row count is bad |
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| 44 | # TODO: check repository id, exception if incorrect |
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| 45 | self.version = data['version'] |
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| 46 | |
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| 47 | def _get_repository(self): |
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| 48 | """ |
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| 49 | Given a database engine, try to guess the repository. |
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| 50 | |
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| 51 | :raise: :exc:`NotImplementedError` |
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| 52 | """ |
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| 53 | # TODO: no guessing yet; for now, a repository must be supplied |
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| 54 | raise NotImplementedError() |
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| 55 | |
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| 56 | @classmethod |
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| 57 | def create(cls, engine, repository, version=None): |
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| 58 | """ |
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| 59 | Declare a database to be under a repository's version control. |
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| 60 | """ |
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| 61 | # Confirm that the version # is valid: positive, integer, |
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| 62 | # exists in repos |
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| 63 | if type(repository) is str: |
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| 64 | repository=Repository(repository) |
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| 65 | version = cls._validate_version(repository, version) |
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| 66 | table=cls._create_table_version(engine, repository, version) |
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| 67 | # TODO: history table |
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| 68 | # Load repository information and return |
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| 69 | return cls(engine, repository) |
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| 70 | |
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| 71 | @classmethod |
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| 72 | def _validate_version(cls, repository, version): |
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| 73 | """ |
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| 74 | Ensures this is a valid version number for this repository. |
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| 75 | |
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| 76 | :raises: :exc:`cls.InvalidVersionError` if invalid |
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| 77 | :return: valid version number |
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| 78 | """ |
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| 79 | if version is None: |
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| 80 | version = 0 |
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| 81 | try: |
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| 82 | version = VerNum(version) # raises valueerror |
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| 83 | if version < 0 or version > repository.latest: |
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| 84 | raise ValueError() |
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| 85 | except ValueError: |
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| 86 | raise exceptions.InvalidVersionError(version) |
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| 87 | return version |
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| 88 | |
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| 89 | @classmethod |
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| 90 | def _create_table_version(cls, engine, repository, version): |
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| 91 | """ |
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| 92 | Creates the versioning table in a database. |
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| 93 | """ |
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| 94 | # Create tables |
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| 95 | tname = repository.version_table |
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| 96 | meta = MetaData(engine) |
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| 97 | |
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| 98 | table = Table( |
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| 99 | tname, meta, |
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| 100 | Column('repository_id', String(255), primary_key=True), |
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| 101 | Column('repository_path', Text), |
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| 102 | Column('version', Integer), ) |
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| 103 | |
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| 104 | if not table.exists(): |
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| 105 | table.create() |
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| 106 | |
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| 107 | # Insert data |
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| 108 | try: |
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| 109 | engine.execute(table.insert(), repository_id=repository.id, |
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| 110 | repository_path=repository.path, |
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| 111 | version=int(version)) |
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| 112 | except sa_exceptions.IntegrityError: |
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| 113 | # An Entry for this repo already exists. |
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| 114 | raise exceptions.DatabaseAlreadyControlledError() |
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| 115 | return table |
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| 116 | |
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| 117 | @classmethod |
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| 118 | def compare_model_to_db(cls, engine, model, repository): |
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| 119 | """ |
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| 120 | Compare the current model against the current database. |
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| 121 | """ |
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| 122 | if isinstance(repository, basestring): |
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| 123 | repository=Repository(repository) |
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| 124 | model = load_model(model) |
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| 125 | diff = schemadiff.getDiffOfModelAgainstDatabase( |
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| 126 | model, engine, excludeTables=[repository.version_table]) |
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| 127 | return diff |
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| 128 | |
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| 129 | @classmethod |
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| 130 | def create_model(cls, engine, repository, declarative=False): |
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| 131 | """ |
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| 132 | Dump the current database as a Python model. |
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| 133 | """ |
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| 134 | if isinstance(repository, basestring): |
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| 135 | repository=Repository(repository) |
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| 136 | diff = schemadiff.getDiffOfModelAgainstDatabase( |
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| 137 | MetaData(), engine, excludeTables=[repository.version_table]) |
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| 138 | return genmodel.ModelGenerator(diff, declarative).toPython() |
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| 139 | |
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| 140 | def update_db_from_model(self, model): |
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| 141 | """ |
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| 142 | Modify the database to match the structure of the current Python model. |
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| 143 | """ |
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| 144 | if isinstance(self.repository, basestring): |
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| 145 | self.repository=Repository(self.repository) |
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| 146 | model = load_model(model) |
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| 147 | diff = schemadiff.getDiffOfModelAgainstDatabase( |
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| 148 | model, self.engine, excludeTables=[self.repository.version_table]) |
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| 149 | genmodel.ModelGenerator(diff).applyModel() |
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| 150 | update = self.table.update( |
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| 151 | self.table.c.repository_id == str(self.repository.id)) |
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| 152 | self.engine.execute(update, version=int(self.repository.latest)) |
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| 153 | |
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| 154 | def drop(self): |
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| 155 | """ |
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| 156 | Remove version control from a database. |
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| 157 | """ |
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| 158 | try: |
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| 159 | self.table.drop() |
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| 160 | except (sa_exceptions.SQLError): |
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| 161 | raise exceptions.DatabaseNotControlledError(str(self.table)) |
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| 162 | |
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| 163 | def _engine_db(self, engine): |
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| 164 | """ |
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| 165 | Returns the database name of an engine - ``postgres``, ``sqlite`` ... |
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| 166 | """ |
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| 167 | # TODO: This is a bit of a hack... |
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| 168 | return str(engine.dialect.__module__).split('.')[-1] |
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| 169 | |
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| 170 | def changeset(self, version=None): |
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| 171 | database = self._engine_db(self.engine) |
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| 172 | start_ver = self.version |
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| 173 | changeset = self.repository.changeset(database, start_ver, version) |
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| 174 | return changeset |
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| 175 | |
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| 176 | def runchange(self, ver, change, step): |
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| 177 | startver = ver |
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| 178 | endver = ver + step |
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| 179 | # Current database version must be correct! Don't run if corrupt! |
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| 180 | if self.version != startver: |
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| 181 | raise exceptions.InvalidVersionError("%s is not %s" % \ |
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| 182 | (self.version, startver)) |
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| 183 | # Run the change |
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| 184 | change.run(self.engine, step) |
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| 185 | # Update/refresh database version |
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| 186 | update = self.table.update( |
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| 187 | and_(self.table.c.version == int(startver), |
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| 188 | self.table.c.repository_id == str(self.repository.id))) |
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| 189 | self.engine.execute(update, version=int(endver)) |
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| 190 | self._load() |
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| 191 | |
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| 192 | def upgrade(self, version=None): |
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| 193 | """ |
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| 194 | Upgrade (or downgrade) to a specified version, or latest version. |
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| 195 | """ |
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| 196 | changeset = self.changeset(version) |
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| 197 | for ver, change in changeset: |
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| 198 | self.runchange(ver, change, changeset.step) |
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