157 lines
5.3 KiB
Python
157 lines
5.3 KiB
Python
"""
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`SQLite`_ database specific implementations of changeset classes.
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.. _`SQLite`: http://www.sqlite.org/
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"""
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try: # Python 3
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from collections import MutableMapping as DictMixin
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except ImportError: # Python 2
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from UserDict import DictMixin
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from copy import copy
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from sqlalchemy.databases import sqlite as sa_base
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from migrate import exceptions
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from migrate.changeset import ansisql
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SQLiteSchemaGenerator = sa_base.SQLiteDDLCompiler
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class SQLiteCommon(object):
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def _not_supported(self, op):
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raise exceptions.NotSupportedError("SQLite does not support "
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"%s; see http://www.sqlite.org/lang_altertable.html" % op)
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class SQLiteHelper(SQLiteCommon):
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def recreate_table(self,table,column=None,delta=None):
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table_name = self.preparer.format_table(table)
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# we remove all indexes so as not to have
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# problems during copy and re-create
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for index in table.indexes:
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index.drop()
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self.append('ALTER TABLE %s RENAME TO migration_tmp' % table_name)
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self.execute()
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insertion_string = self._modify_table(table, column, delta)
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table.create(bind=self.connection)
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self.append(insertion_string % {'table_name': table_name})
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self.execute()
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self.append('DROP TABLE migration_tmp')
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self.execute()
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def visit_column(self, delta):
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if isinstance(delta, DictMixin):
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column = delta.result_column
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table = self._to_table(delta.table)
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else:
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column = delta
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table = self._to_table(column.table)
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self.recreate_table(table,column,delta)
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class SQLiteColumnGenerator(SQLiteSchemaGenerator,
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ansisql.ANSIColumnGenerator,
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# at the end so we get the normal
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# visit_column by default
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SQLiteHelper,
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SQLiteCommon
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):
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"""SQLite ColumnGenerator"""
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def _modify_table(self, table, column, delta):
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columns = ' ,'.join(map(
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self.preparer.format_column,
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[c for c in table.columns if c.name!=column.name]))
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return ('INSERT INTO %%(table_name)s (%(cols)s) '
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'SELECT %(cols)s from migration_tmp')%{'cols':columns}
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def visit_column(self,column):
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if column.foreign_keys:
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SQLiteHelper.visit_column(self,column)
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else:
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super(SQLiteColumnGenerator,self).visit_column(column)
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class SQLiteColumnDropper(SQLiteHelper, ansisql.ANSIColumnDropper):
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"""SQLite ColumnDropper"""
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def _modify_table(self, table, column, delta):
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columns = ' ,'.join(map(self.preparer.format_column, table.columns))
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return 'INSERT INTO %(table_name)s SELECT ' + columns + \
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' from migration_tmp'
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def visit_column(self,column):
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# For SQLite, we *have* to remove the column here so the table
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# is re-created properly.
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column.remove_from_table(column.table,unset_table=False)
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super(SQLiteColumnDropper,self).visit_column(column)
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class SQLiteSchemaChanger(SQLiteHelper, ansisql.ANSISchemaChanger):
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"""SQLite SchemaChanger"""
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def _modify_table(self, table, column, delta):
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return 'INSERT INTO %(table_name)s SELECT * from migration_tmp'
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def visit_index(self, index):
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"""Does not support ALTER INDEX"""
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self._not_supported('ALTER INDEX')
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class SQLiteConstraintGenerator(ansisql.ANSIConstraintGenerator, SQLiteHelper, SQLiteCommon):
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def visit_migrate_primary_key_constraint(self, constraint):
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tmpl = "CREATE UNIQUE INDEX %s ON %s ( %s )"
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cols = ', '.join(map(self.preparer.format_column, constraint.columns))
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tname = self.preparer.format_table(constraint.table)
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name = self.get_constraint_name(constraint)
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msg = tmpl % (name, tname, cols)
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self.append(msg)
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self.execute()
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def _modify_table(self, table, column, delta):
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return 'INSERT INTO %(table_name)s SELECT * from migration_tmp'
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def visit_migrate_foreign_key_constraint(self, *p, **k):
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self.recreate_table(p[0].table)
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def visit_migrate_unique_constraint(self, *p, **k):
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self.recreate_table(p[0].table)
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class SQLiteConstraintDropper(ansisql.ANSIColumnDropper,
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SQLiteCommon,
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ansisql.ANSIConstraintCommon):
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def visit_migrate_primary_key_constraint(self, constraint):
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tmpl = "DROP INDEX %s "
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name = self.get_constraint_name(constraint)
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msg = tmpl % (name)
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self.append(msg)
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self.execute()
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def visit_migrate_foreign_key_constraint(self, *p, **k):
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self._not_supported('ALTER TABLE DROP CONSTRAINT')
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def visit_migrate_check_constraint(self, *p, **k):
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self._not_supported('ALTER TABLE DROP CONSTRAINT')
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def visit_migrate_unique_constraint(self, *p, **k):
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self._not_supported('ALTER TABLE DROP CONSTRAINT')
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# TODO: technically primary key is a NOT NULL + UNIQUE constraint, should add NOT NULL to index
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class SQLiteDialect(ansisql.ANSIDialect):
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columngenerator = SQLiteColumnGenerator
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columndropper = SQLiteColumnDropper
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schemachanger = SQLiteSchemaChanger
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constraintgenerator = SQLiteConstraintGenerator
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constraintdropper = SQLiteConstraintDropper
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