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- 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 _unique_should_be_added(self, old_field, new_field):
- return (
- super()._unique_should_be_added(old_field, new_field) and
- not self._field_became_primary_key(old_field, new_field)
- )
-
- 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),
- })
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