django1/django/db/backends/oracle/schema.py

96 lines
3.8 KiB
Python

import copy
from django.db.backends.schema import BaseDatabaseSchemaEditor
from django.db.utils import DatabaseError
class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
sql_create_column = "ALTER TABLE %(table)s ADD %(column)s %(definition)s"
sql_alter_column_type = "MODIFY %(column)s %(type)s"
sql_alter_column_null = "MODIFY %(column)s NULL"
sql_alter_column_not_null = "MODIFY %(column)s NOT NULL"
sql_alter_column_default = "MODIFY %(column)s DEFAULT %(default)s"
sql_alter_column_no_default = "MODIFY %(column)s DEFAULT NULL"
sql_delete_column = "ALTER TABLE %(table)s DROP COLUMN %(column)s"
sql_delete_table = "DROP TABLE %(table)s CASCADE CONSTRAINTS"
def delete_model(self, model):
# Run superclass action
super(DatabaseSchemaEditor, self).delete_model(model)
# Clean up any autoincrement trigger
self.execute("""
DECLARE
i INTEGER;
BEGIN
SELECT COUNT(*) INTO i FROM USER_CATALOG
WHERE TABLE_NAME = '%(sq_name)s' AND TABLE_TYPE = 'SEQUENCE';
IF i = 1 THEN
EXECUTE IMMEDIATE 'DROP SEQUENCE "%(sq_name)s"';
END IF;
END;
/""" % {'sq_name': self.connection.ops._get_sequence_name(model._meta.db_table)})
def alter_field(self, model, old_field, new_field, strict=False):
try:
# Run superclass action
super(DatabaseSchemaEditor, self).alter_field(model, old_field, new_field, strict)
except DatabaseError as e:
description = str(e)
# If we're changing to/from LOB fields, we need to do a
# SQLite-ish workaround
if 'ORA-22858' in description or 'ORA-22859' in description:
self._alter_field_lob_workaround(model, old_field, new_field)
else:
raise
def _alter_field_lob_workaround(self, model, old_field, new_field):
"""
Oracle refuses to change a column type from/to LOB to/from a regular
column. In Django, this shows up when the field is changed from/to
a TextField.
What we need to do instead is:
- Add the desired field with a temporary name
- Update the table to transfer values from old to new
- Drop old column
- Rename the new column
"""
# Make a new field that's like the new one but with a temporary
# column name.
new_temp_field = copy.deepcopy(new_field)
new_temp_field.column = self._generate_temp_name(new_field.column)
# Add it
self.add_field(model, new_temp_field)
# Transfer values across
self.execute("UPDATE %s set %s=%s" % (
self.quote_name(model._meta.db_table),
self.quote_name(new_temp_field.column),
self.quote_name(old_field.column),
))
# Drop the old field
self.remove_field(model, old_field)
# Rename the new field
self.alter_field(model, new_temp_field, new_field)
# Close the connection to force cx_Oracle to get column types right
# on a new cursor
self.connection.close()
def normalize_name(self, name):
"""
Get the properly shortened and uppercased identifier as returned by quote_name(), but without the actual quotes.
"""
nn = self.quote_name(name)
if nn[0] == '"' and nn[-1] == '"':
nn = nn[1:-1]
return nn
def _generate_temp_name(self, for_name):
"""
Generates temporary names for workarounds that need temp columns
"""
suffix = hex(hash(for_name)).upper()[1:]
return self.normalize_name(for_name + "_" + suffix)
def prepare_default(self, value):
return self.connection.ops.quote_parameter(value)