133 lines
4.4 KiB
Python
133 lines
4.4 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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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.changeset import ansisql, exceptions, SQLA_06
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if not SQLA_06:
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SQLiteSchemaGenerator = sa_base.SQLiteSchemaGenerator
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else:
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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 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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table_name = self.preparer.format_table(table)
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# we remove all constraints, indexes so it doesnt recreate them
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ixbackup = copy(table.indexes)
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consbackup = copy(table.constraints)
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table.indexes = set()
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table.constraints = set()
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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()
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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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# restore indexes, constraints
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table.indexes = ixbackup
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table.constraints = consbackup
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class SQLiteColumnGenerator(SQLiteSchemaGenerator, SQLiteCommon,
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ansisql.ANSIColumnGenerator):
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"""SQLite ColumnGenerator"""
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def add_foreignkey(self, constraint):
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"""Does not support ALTER TABLE ADD FOREIGN KEY"""
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self._not_supported("ALTER TABLE ADD CONSTRAINT")
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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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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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column = table.columns[delta.current_name]
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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, 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 visit_migrate_foreign_key_constraint(self, *p, **k):
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self._not_supported('ALTER TABLE ADD CONSTRAINT')
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def visit_migrate_unique_constraint(self, *p, **k):
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self._not_supported('ALTER TABLE ADD CONSTRAINT')
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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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