import copy import datetime import re from django.db.backends.base.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 quote_value(self, value): if isinstance(value, (datetime.date, datetime.time, datetime.datetime)): return "'%s'" % value elif isinstance(value, str): return "'%s'" % value.replace("\'", "\'\'") elif isinstance(value, (bytes, bytearray, memoryview)): return "'%s'" % value.hex() elif isinstance(value, bool): return "1" if value else "0" else: return str(value) def remove_field(self, model, field): # If the column is an identity column, drop the identity before # removing the field. if self._is_identity_column(model._meta.db_table, field.column): self._drop_identity(model._meta.db_table, field.column) super().remove_field(model, field) def delete_model(self, model): # Run superclass action super().delete_model(model) # Clean up manually created sequence. self.execute(""" DECLARE i INTEGER; BEGIN SELECT COUNT(1) INTO i FROM USER_SEQUENCES WHERE SEQUENCE_NAME = '%(sq_name)s'; IF i = 1 THEN EXECUTE IMMEDIATE 'DROP SEQUENCE "%(sq_name)s"'; END IF; END; /""" % {'sq_name': self.connection.ops._get_no_autofield_sequence_name(model._meta.db_table)}) def alter_field(self, model, old_field, new_field, strict=False): try: super().alter_field(model, old_field, new_field, strict) except DatabaseError as e: description = str(e) # If we're changing type to an unsupported type we need a # SQLite-ish workaround if 'ORA-22858' in description or 'ORA-22859' in description: self._alter_field_type_workaround(model, old_field, new_field) # If an identity column is changing to a non-numeric type, drop the # identity first. elif 'ORA-30675' in description: self._drop_identity(model._meta.db_table, old_field.column) self.alter_field(model, old_field, new_field, strict) # If a primary key column is changing to an identity column, drop # the primary key first. elif 'ORA-30673' in description and old_field.primary_key: self._delete_primary_key(model, strict=True) self._alter_field_type_workaround(model, old_field, new_field) else: raise def _alter_field_type_workaround(self, model, old_field, new_field): """ Oracle refuses to change from some type to other type. What we need to do instead is: - Add a nullable version of the desired field with a temporary name. If the new column is an auto field, then the temporary column can't be nullable. - Update the table to transfer values from old to new - Drop old column - Rename the new column and possibly drop the nullable property """ # 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.null = (new_field.get_internal_type() not in ('AutoField', 'BigAutoField')) new_temp_field.column = self._generate_temp_name(new_field.column) # Add it self.add_field(model, new_temp_field) # Explicit data type conversion # https://docs.oracle.com/database/121/SQLRF/sql_elements002.htm#SQLRF51054 new_value = self.quote_name(old_field.column) old_type = old_field.db_type(self.connection) if re.match('^N?CLOB', old_type): new_value = "TO_CHAR(%s)" % new_value old_type = 'VARCHAR2' if re.match('^N?VARCHAR2', old_type): new_internal_type = new_field.get_internal_type() if new_internal_type == 'DateField': new_value = "TO_DATE(%s, 'YYYY-MM-DD')" % new_value elif new_internal_type == 'DateTimeField': new_value = "TO_TIMESTAMP(%s, 'YYYY-MM-DD HH24:MI:SS.FF')" % new_value elif new_internal_type == 'TimeField': # TimeField are stored as TIMESTAMP with a 1900-01-01 date part. new_value = "TO_TIMESTAMP(CONCAT('1900-01-01 ', %s), 'YYYY-MM-DD HH24:MI:SS.FF')" % new_value # Transfer values across self.execute("UPDATE %s set %s=%s" % ( self.quote_name(model._meta.db_table), self.quote_name(new_temp_field.column), new_value, )) # Drop the old field self.remove_field(model, old_field) # Rename and possibly make the new field NOT NULL super().alter_field(model, new_temp_field, new_field) def normalize_name(self, name): """ Get the properly shortened and uppercased identifier as returned by quote_name() but without the 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): """Generate 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.quote_value(value) def _field_should_be_indexed(self, model, field): create_index = super()._field_should_be_indexed(model, field) db_type = field.db_type(self.connection) if db_type is not None and db_type.lower() in self.connection._limited_data_types: return False return create_index def _is_identity_column(self, table_name, column_name): with self.connection.cursor() as cursor: cursor.execute(""" SELECT CASE WHEN identity_column = 'YES' THEN 1 ELSE 0 END FROM user_tab_cols WHERE table_name = %s AND column_name = %s """, [self.normalize_name(table_name), self.normalize_name(column_name)]) row = cursor.fetchone() return row[0] if row else False def _drop_identity(self, table_name, column_name): self.execute('ALTER TABLE %(table)s MODIFY %(column)s DROP IDENTITY' % { 'table': self.quote_name(table_name), 'column': self.quote_name(column_name), })