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"""
`SQLite`_ database specific implementations of changeset classes.
.. _`SQLite`: http://www.sqlite.org/
"""
from migrate.changeset import ansisql, constraint, exceptions
from sqlalchemy.databases import sqlite as sa_base
from sqlalchemy import Table, MetaData
#import sqlalchemy as sa
SQLiteSchemaGenerator = sa_base.SQLiteSchemaGenerator
class SQLiteHelper(object):
def visit_column(self, param):
try:
table = self._to_table(param.table)
except:
table = self._to_table(param)
raise
table_name = self.preparer.format_table(table)
self.append('ALTER TABLE %s RENAME TO migration_tmp' % table_name)
self.execute()
insertion_string = self._modify_table(table, param)
table.create()
self.append(insertion_string % {'table_name': table_name})
self.execute()
self.append('DROP TABLE migration_tmp')
self.execute()
class SQLiteColumnGenerator(SQLiteSchemaGenerator,
ansisql.ANSIColumnGenerator):
pass
class SQLiteColumnDropper(SQLiteHelper, ansisql.ANSIColumnDropper):
def _modify_table(self, table, column):
del table.columns[column.name]
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):
def _not_supported(self, op):
raise exceptions.NotSupportedError("SQLite does not support "
"%s; see http://www.sqlite.org/lang_altertable.html" % op)
def _modify_table(self, table, delta):
column = table.columns[delta.current_name]
for k, v in delta.items():
setattr(column, k, v)
return 'INSERT INTO %(table_name)s SELECT * from migration_tmp'
def visit_index(self, param):
self._not_supported('ALTER INDEX')
class SQLiteConstraintGenerator(ansisql.ANSIConstraintGenerator):
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()
class SQLiteFKGenerator(SQLiteSchemaChanger, ansisql.ANSIFKGenerator):
def visit_column(self, column):
"""Create foreign keys for a column (table already exists); #32"""
if self.fk:
self._not_supported("ALTER TABLE ADD FOREIGN KEY")
if self.buffer.getvalue() != '':
self.execute()
class SQLiteConstraintDropper(ansisql.ANSIColumnDropper, 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()
class SQLiteDialect(ansisql.ANSIDialect):
columngenerator = SQLiteColumnGenerator
columndropper = SQLiteColumnDropper
schemachanger = SQLiteSchemaChanger
constraintgenerator = SQLiteConstraintGenerator
constraintdropper = SQLiteConstraintDropper
columnfkgenerator = SQLiteFKGenerator
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