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"""
`SQLite`_ database specific implementations of changeset classes.
.. _`SQLite`: http://www.sqlite.org/
"""
from UserDict import DictMixin
from copy import copy
from sqlalchemy.databases import sqlite as sa_base
from migrate.changeset import ansisql, exceptions, SQLA_06
if not SQLA_06:
SQLiteSchemaGenerator = sa_base.SQLiteSchemaGenerator
else:
SQLiteSchemaGenerator = sa_base.SQLiteDDLCompiler
class SQLiteCommon(object):
def _not_supported(self, op):
raise exceptions.NotSupportedError("SQLite does not support "
"%s; see http://www.sqlite.org/lang_altertable.html" % op)
class SQLiteHelper(SQLiteCommon):
def visit_column(self, delta):
if isinstance(delta, DictMixin):
column = delta.result_column
table = self._to_table(delta.table)
else:
column = delta
table = self._to_table(column.table)
table_name = self.preparer.format_table(table)
# we remove all constraints, indexes so it doesnt recreate them
ixbackup = copy(table.indexes)
consbackup = copy(table.constraints)
table.indexes = set()
table.constraints = set()
self.append('ALTER TABLE %s RENAME TO migration_tmp' % table_name)
self.execute()
insertion_string = self._modify_table(table, column, delta)
table.create()
self.append(insertion_string % {'table_name': table_name})
self.execute()
self.append('DROP TABLE migration_tmp')
self.execute()
# restore indexes, constraints
table.indexes = ixbackup
table.constraints = consbackup
class SQLiteColumnGenerator(SQLiteSchemaGenerator, SQLiteCommon,
ansisql.ANSIColumnGenerator):
"""SQLite ColumnGenerator"""
def add_foreignkey(self, constraint):
"""Does not support ALTER TABLE ADD FOREIGN KEY"""
self._not_supported("ALTER TABLE ADD CONSTRAINT")
class SQLiteColumnDropper(SQLiteHelper, ansisql.ANSIColumnDropper):
"""SQLite ColumnDropper"""
def _modify_table(self, table, column, delta):
columns = ' ,'.join(map(self.preparer.format_column, table.columns))
return 'INSERT INTO %(table_name)s SELECT ' + columns + \
' from migration_tmp'
class SQLiteSchemaChanger(SQLiteHelper, ansisql.ANSISchemaChanger):
"""SQLite SchemaChanger"""
def _modify_table(self, table, column, delta):
column = table.columns[delta.current_name]
return 'INSERT INTO %(table_name)s SELECT * from migration_tmp'
def visit_index(self, index):
"""Does not support ALTER INDEX"""
self._not_supported('ALTER INDEX')
class SQLiteConstraintGenerator(ansisql.ANSIConstraintGenerator, SQLiteCommon):
def visit_migrate_primary_key_constraint(self, constraint):
tmpl = "CREATE UNIQUE INDEX %s ON %s ( %s )"
cols = ', '.join(map(self.preparer.format_column, constraint.columns))
tname = self.preparer.format_table(constraint.table)
name = self.get_constraint_name(constraint)
msg = tmpl % (name, tname, cols)
self.append(msg)
self.execute()
def visit_migrate_foreign_key_constraint(self, *p, **k):
self._not_supported('ALTER TABLE ADD CONSTRAINT')
def visit_migrate_unique_constraint(self, *p, **k):
self._not_supported('ALTER TABLE ADD CONSTRAINT')
class SQLiteConstraintDropper(ansisql.ANSIColumnDropper,
SQLiteCommon,
ansisql.ANSIConstraintCommon):
def visit_migrate_primary_key_constraint(self, constraint):
tmpl = "DROP INDEX %s "
name = self.get_constraint_name(constraint)
msg = tmpl % (name)
self.append(msg)
self.execute()
def visit_migrate_foreign_key_constraint(self, *p, **k):
self._not_supported('ALTER TABLE DROP CONSTRAINT')
def visit_migrate_check_constraint(self, *p, **k):
self._not_supported('ALTER TABLE DROP CONSTRAINT')
def visit_migrate_unique_constraint(self, *p, **k):
self._not_supported('ALTER TABLE DROP CONSTRAINT')
# TODO: technically primary key is a NOT NULL + UNIQUE constraint, should add NOT NULL to index
class SQLiteDialect(ansisql.ANSIDialect):
columngenerator = SQLiteColumnGenerator
columndropper = SQLiteColumnDropper
schemachanger = SQLiteSchemaChanger
constraintgenerator = SQLiteConstraintGenerator
constraintdropper = SQLiteConstraintDropper
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