108 lines
4.5 KiB
Python
108 lines
4.5 KiB
Python
from django.db.backends.base.schema import BaseDatabaseSchemaEditor
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from django.db.models import NOT_PROVIDED
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class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
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sql_rename_table = "RENAME TABLE %(old_table)s TO %(new_table)s"
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sql_alter_column_null = "MODIFY %(column)s %(type)s NULL"
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sql_alter_column_not_null = "MODIFY %(column)s %(type)s NOT NULL"
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sql_alter_column_type = "MODIFY %(column)s %(type)s"
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# No 'CASCADE' which works as a no-op in MySQL but is undocumented
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sql_delete_column = "ALTER TABLE %(table)s DROP COLUMN %(column)s"
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sql_rename_column = "ALTER TABLE %(table)s CHANGE %(old_column)s %(new_column)s %(type)s"
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sql_delete_unique = "ALTER TABLE %(table)s DROP INDEX %(name)s"
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sql_delete_fk = "ALTER TABLE %(table)s DROP FOREIGN KEY %(name)s"
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sql_delete_index = "DROP INDEX %(name)s ON %(table)s"
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sql_create_pk = "ALTER TABLE %(table)s ADD CONSTRAINT %(name)s PRIMARY KEY (%(columns)s)"
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sql_delete_pk = "ALTER TABLE %(table)s DROP PRIMARY KEY"
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def quote_value(self, value):
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# Inner import to allow module to fail to load gracefully
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import MySQLdb.converters
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return MySQLdb.escape(value, MySQLdb.converters.conversions)
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def skip_default(self, field):
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"""
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MySQL doesn't accept default values for some data types and implicitly
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treats these columns as nullable.
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"""
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db_type = field.db_type(self.connection)
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return (
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db_type is not None and
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db_type.lower() in {
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'tinyblob', 'blob', 'mediumblob', 'longblob',
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'tinytext', 'text', 'mediumtext', 'longtext',
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'json',
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}
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)
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def add_field(self, model, field):
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super().add_field(model, field)
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# Simulate the effect of a one-off default.
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# field.default may be unhashable, so a set isn't used for "in" check.
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if self.skip_default(field) and field.default not in (None, NOT_PROVIDED):
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effective_default = self.effective_default(field)
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self.execute('UPDATE %(table)s SET %(column)s = %%s' % {
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'table': self.quote_name(model._meta.db_table),
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'column': self.quote_name(field.column),
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}, [effective_default])
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def _field_should_be_indexed(self, model, field):
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create_index = super()._field_should_be_indexed(model, field)
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storage = self.connection.introspection.get_storage_engine(
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self.connection.cursor(), model._meta.db_table
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)
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# No need to create an index for ForeignKey fields except if
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# db_constraint=False because the index from that constraint won't be
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# created.
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if (storage == "InnoDB" and
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create_index and
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field.get_internal_type() == 'ForeignKey' and
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field.db_constraint):
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return False
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return create_index
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def _delete_composed_index(self, model, fields, *args):
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"""
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MySQL can remove an implicit FK index on a field when that field is
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covered by another index like a unique_together. "covered" here means
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that the more complex index starts like the simpler one.
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http://bugs.mysql.com/bug.php?id=37910 / Django ticket #24757
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We check here before removing the [unique|index]_together if we have to
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recreate a FK index.
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"""
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first_field = model._meta.get_field(fields[0])
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if first_field.get_internal_type() == 'ForeignKey':
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constraint_names = self._constraint_names(model, [first_field.column], index=True)
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if not constraint_names:
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self.execute(self._create_index_sql(model, [first_field], suffix=""))
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return super()._delete_composed_index(model, fields, *args)
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def _set_field_new_type_null_status(self, field, new_type):
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"""
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Keep the null property of the old field. If it has changed, it will be
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handled separately.
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"""
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if field.null:
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new_type += " NULL"
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else:
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new_type += " NOT NULL"
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return new_type
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def _alter_column_type_sql(self, table, old_field, new_field, new_type):
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new_type = self._set_field_new_type_null_status(old_field, new_type)
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return super()._alter_column_type_sql(table, old_field, new_field, new_type)
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def _rename_field_sql(self, table, old_field, new_field, new_type):
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new_type = self._set_field_new_type_null_status(old_field, new_type)
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return super()._rename_field_sql(table, old_field, new_field, new_type)
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