root/galaxy-central/eggs/sqlalchemy_migrate-0.5.4-py2.6.egg/migrate/versioning/genmodel.py

リビジョン 3, 8.3 KB (コミッタ: kohda, 14 年 前)

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1"""
2   Code to generate a Python model from a database or differences
3   between a model and database.
4
5   Some of this is borrowed heavily from the AutoCode project at:
6   http://code.google.com/p/sqlautocode/
7"""
8
9import sys
10
11import migrate
12import sqlalchemy
13
14
15HEADER = """
16## File autogenerated by genmodel.py
17
18from sqlalchemy import *
19meta = MetaData()
20"""
21
22DECLARATIVE_HEADER = """
23## File autogenerated by genmodel.py
24
25from sqlalchemy import *
26from sqlalchemy.ext import declarative
27
28Base = declarative.declarative_base()
29"""
30
31
32class ModelGenerator(object):
33
34    def __init__(self, diff, declarative=False):
35        self.diff = diff
36        self.declarative = declarative
37        # is there an easier way to get this?
38        dialectModule = sys.modules[self.diff.conn.dialect.__module__]
39        self.colTypeMappings = dict((v, k) for k, v in \
40                                        dialectModule.colspecs.items())
41
42    def column_repr(self, col):
43        kwarg = []
44        if col.key != col.name:
45            kwarg.append('key')
46        if col.primary_key:
47            col.primary_key = True  # otherwise it dumps it as 1
48            kwarg.append('primary_key')
49        if not col.nullable:
50            kwarg.append('nullable')
51        if col.onupdate:
52            kwarg.append('onupdate')
53        if col.default:
54            if col.primary_key:
55                # I found that PostgreSQL automatically creates a
56                # default value for the sequence, but let's not show
57                # that.
58                pass
59            else:
60                kwarg.append('default')
61        ks = ', '.join('%s=%r' % (k, getattr(col, k)) for k in kwarg)
62
63        # crs: not sure if this is good idea, but it gets rid of extra
64        # u''
65        name = col.name.encode('utf8')
66        type = self.colTypeMappings.get(col.type.__class__, None)
67        if type:
68            # Make the column type be an instance of this type.
69            type = type()
70        else:
71            # We must already be a model type, no need to map from the
72            # database-specific types.
73            type = col.type
74
75        data = {
76            'name': name,
77            'type': type,
78            'constraints': ', '.join([repr(cn) for cn in col.constraints]),
79            'args': ks and ks or ''}
80
81        if data['constraints']:
82            if data['args']:
83                data['args'] = ',' + data['args']
84
85        if data['constraints'] or data['args']:
86            data['maybeComma'] = ','
87        else:
88            data['maybeComma'] = ''
89
90        commonStuff = """ %(maybeComma)s %(constraints)s %(args)s)""" % data
91        commonStuff = commonStuff.strip()
92        data['commonStuff'] = commonStuff
93        if self.declarative:
94            return """%(name)s = Column(%(type)r%(commonStuff)s""" % data
95        else:
96            return """Column(%(name)r, %(type)r%(commonStuff)s""" % data
97
98    def getTableDefn(self, table):
99        out = []
100        tableName = table.name
101        if self.declarative:
102            out.append("class %(table)s(Base):" % {'table': tableName})
103            out.append("  __tablename__ = '%(table)s'" % {'table': tableName})
104            for col in table.columns:
105                out.append("  %s" % self.column_repr(col))
106        else:
107            out.append("%(table)s = Table('%(table)s', meta," % \
108                           {'table': tableName})
109            for col in table.columns:
110                out.append("  %s," % self.column_repr(col))
111            out.append(")")
112        return out
113
114    def toPython(self):
115        """Assume database is current and model is empty."""
116        out = []
117        if self.declarative:
118            out.append(DECLARATIVE_HEADER)
119        else:
120            out.append(HEADER)
121        out.append("")
122        for table in self.diff.tablesMissingInModel:
123            out.extend(self.getTableDefn(table))
124            out.append("")
125        return '\n'.join(out)
126
127    def toUpgradeDowngradePython(self, indent='    '):
128        ''' Assume model is most current and database is out-of-date. '''
129
130        decls = ['meta = MetaData(migrate_engine)']
131        for table in self.diff.tablesMissingInModel + \
132                self.diff.tablesMissingInDatabase:
133            decls.extend(self.getTableDefn(table))
134
135        upgradeCommands, downgradeCommands = [], []
136        for table in self.diff.tablesMissingInModel:
137            tableName = table.name
138            upgradeCommands.append("%(table)s.drop()" % {'table': tableName})
139            downgradeCommands.append("%(table)s.create()" % \
140                                         {'table': tableName})
141        for table in self.diff.tablesMissingInDatabase:
142            tableName = table.name
143            upgradeCommands.append("%(table)s.create()" % {'table': tableName})
144            downgradeCommands.append("%(table)s.drop()" % {'table': tableName})
145
146        return (
147            '\n'.join(decls),
148            '\n'.join(['%s%s' % (indent, line) for line in upgradeCommands]),
149            '\n'.join(['%s%s' % (indent, line) for line in downgradeCommands]))
150
151    def applyModel(self):
152        """Apply model to current database."""
153        # Yuck! We have to import from changeset to apply the
154        # monkey-patch to allow column adding/dropping.
155        from migrate.changeset import schema
156
157        def dbCanHandleThisChange(missingInDatabase, missingInModel, diffDecl):
158            if missingInDatabase and not missingInModel and not diffDecl:
159                # Even sqlite can handle this.
160                return True
161            else:
162                return not self.diff.conn.url.drivername.startswith('sqlite')
163
164        meta = sqlalchemy.MetaData(self.diff.conn.engine)
165
166        for table in self.diff.tablesMissingInModel:
167            table = table.tometadata(meta)
168            table.drop()
169        for table in self.diff.tablesMissingInDatabase:
170            table = table.tometadata(meta)
171            table.create()
172        for modelTable in self.diff.tablesWithDiff:
173            modelTable = modelTable.tometadata(meta)
174            dbTable = self.diff.reflected_model.tables[modelTable.name]
175            tableName = modelTable.name
176            missingInDatabase, missingInModel, diffDecl = \
177                self.diff.colDiffs[tableName]
178            if dbCanHandleThisChange(missingInDatabase, missingInModel,
179                                     diffDecl):
180                for col in missingInDatabase:
181                    modelTable.columns[col.name].create()
182                for col in missingInModel:
183                    dbTable.columns[col.name].drop()
184                for modelCol, databaseCol, modelDecl, databaseDecl in diffDecl:
185                    databaseCol.alter(modelCol)
186            else:
187                # Sqlite doesn't support drop column, so you have to
188                # do more: create temp table, copy data to it, drop
189                # old table, create new table, copy data back.
190                #
191                # I wonder if this is guaranteed to be unique?
192                tempName = '_temp_%s' % modelTable.name
193
194                def getCopyStatement():
195                    preparer = self.diff.conn.engine.dialect.preparer
196                    commonCols = []
197                    for modelCol in modelTable.columns:
198                        if modelCol.name in dbTable.columns:
199                            commonCols.append(modelCol.name)
200                    commonColsStr = ', '.join(commonCols)
201                    return 'INSERT INTO %s (%s) SELECT %s FROM %s' % \
202                        (tableName, commonColsStr, commonColsStr, tempName)
203
204                # Move the data in one transaction, so that we don't
205                # leave the database in a nasty state.
206                connection = self.diff.conn.connect()
207                trans = connection.begin()
208                try:
209                    connection.execute(
210                        'CREATE TEMPORARY TABLE %s as SELECT * from %s' % \
211                            (tempName, modelTable.name))
212                    # make sure the drop takes place inside our
213                    # transaction with the bind parameter
214                    modelTable.drop(bind=connection)
215                    modelTable.create(bind=connection)
216                    connection.execute(getCopyStatement())
217                    connection.execute('DROP TABLE %s' % tempName)
218                    trans.commit()
219                except:
220                    trans.rollback()
221                    raise
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