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