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"""
Oracle database specific implementations of changeset classes.
"""
import sqlalchemy as sa
from sqlalchemy.databases import oracle as sa_base
from migrate.changeset import ansisql, exceptions
OracleSchemaGenerator = sa_base.OracleSchemaGenerator
class OracleColumnGenerator(OracleSchemaGenerator, ansisql.ANSIColumnGenerator):
pass
class OracleColumnDropper(ansisql.ANSIColumnDropper):
pass
class OracleSchemaChanger(OracleSchemaGenerator, ansisql.ANSISchemaChanger):
def get_column_specification(self, column, **kwargs):
# Ignore the NOT NULL generated
override_nullable = kwargs.pop('override_nullable', None)
if override_nullable:
orig = column.nullable
column.nullable = True
ret = super(OracleSchemaChanger, self).get_column_specification(
column, **kwargs)
if override_nullable:
column.nullable = orig
return ret
def visit_column(self, delta):
keys = delta.keys()
if 'name' in keys:
self._run_subvisit(delta,
self._visit_column_name,
start_alter=False)
if len(set(('type', 'nullable', 'server_default')).intersection(keys)):
self._run_subvisit(delta,
self._visit_column_change,
start_alter=False)
def _visit_column_change(self, table, column, delta):
# Oracle cannot drop a default once created, but it can set it
# to null. We'll do that if default=None
# http://forums.oracle.com/forums/message.jspa?messageID=1273234#1273234
dropdefault_hack = (column.server_default is None \
and 'server_default' in delta.keys())
# Oracle apparently doesn't like it when we say "not null" if
# the column's already not null. Fudge it, so we don't need a
# new function
notnull_hack = ((not column.nullable) \
and ('nullable' not in delta.keys()))
# We need to specify NULL if we're removing a NOT NULL
# constraint
null_hack = (column.nullable and ('nullable' in delta.keys()))
if dropdefault_hack:
column.server_default = sa.PassiveDefault(sa.sql.null())
if notnull_hack:
column.nullable = True
colspec = self.get_column_specification(column,
override_nullable=null_hack)
if null_hack:
colspec += ' NULL'
if notnull_hack:
column.nullable = False
if dropdefault_hack:
column.server_default = None
self.start_alter_table(table)
self.append("MODIFY (")
self.append(colspec)
self.append(")")
class OracleConstraintCommon(object):
def get_constraint_name(self, cons):
# Oracle constraints can't guess their name like other DBs
if not cons.name:
raise exceptions.NotSupportedError(
"Oracle constraint names must be explicitly stated")
return cons.name
class OracleConstraintGenerator(OracleConstraintCommon,
ansisql.ANSIConstraintGenerator):
pass
class OracleConstraintDropper(OracleConstraintCommon,
ansisql.ANSIConstraintDropper):
pass
class OracleDialect(ansisql.ANSIDialect):
columngenerator = OracleColumnGenerator
columndropper = OracleColumnDropper
schemachanger = OracleSchemaChanger
constraintgenerator = OracleConstraintGenerator
constraintdropper = OracleConstraintDropper
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