1064 lines
49 KiB
Python
1064 lines
49 KiB
Python
import hashlib
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import logging
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from datetime import datetime
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from django.db.backends.ddl_references import (
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Columns, ForeignKeyName, IndexName, Statement, Table,
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)
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from django.db.backends.utils import split_identifier
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from django.db.models import Index
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from django.db.transaction import TransactionManagementError, atomic
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from django.utils import timezone
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from django.utils.encoding import force_bytes
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logger = logging.getLogger('django.db.backends.schema')
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def _is_relevant_relation(relation, altered_field):
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"""
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When altering the given field, must constraints on its model from the given
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relation be temporarily dropped?
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"""
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field = relation.field
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if field.many_to_many:
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# M2M reverse field
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return False
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if altered_field.primary_key and field.to_fields == [None]:
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# Foreign key constraint on the primary key, which is being altered.
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return True
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# Is the constraint targeting the field being altered?
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return altered_field.name in field.to_fields
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def _related_non_m2m_objects(old_field, new_field):
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# Filter out m2m objects from reverse relations.
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# Return (old_relation, new_relation) tuples.
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return zip(
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(obj for obj in old_field.model._meta.related_objects if _is_relevant_relation(obj, old_field)),
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(obj for obj in new_field.model._meta.related_objects if _is_relevant_relation(obj, new_field))
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)
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class BaseDatabaseSchemaEditor:
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"""
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This class and its subclasses are responsible for emitting schema-changing
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statements to the databases - model creation/removal/alteration, field
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renaming, index fiddling, and so on.
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"""
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# Overrideable SQL templates
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sql_create_table = "CREATE TABLE %(table)s (%(definition)s)"
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sql_rename_table = "ALTER TABLE %(old_table)s RENAME TO %(new_table)s"
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sql_retablespace_table = "ALTER TABLE %(table)s SET TABLESPACE %(new_tablespace)s"
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sql_delete_table = "DROP TABLE %(table)s CASCADE"
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sql_create_column = "ALTER TABLE %(table)s ADD COLUMN %(column)s %(definition)s"
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sql_alter_column = "ALTER TABLE %(table)s %(changes)s"
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sql_alter_column_type = "ALTER COLUMN %(column)s TYPE %(type)s"
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sql_alter_column_null = "ALTER COLUMN %(column)s DROP NOT NULL"
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sql_alter_column_not_null = "ALTER COLUMN %(column)s SET NOT NULL"
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sql_alter_column_default = "ALTER COLUMN %(column)s SET DEFAULT %(default)s"
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sql_alter_column_no_default = "ALTER COLUMN %(column)s DROP DEFAULT"
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sql_delete_column = "ALTER TABLE %(table)s DROP COLUMN %(column)s CASCADE"
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sql_rename_column = "ALTER TABLE %(table)s RENAME COLUMN %(old_column)s TO %(new_column)s"
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sql_update_with_default = "UPDATE %(table)s SET %(column)s = %(default)s WHERE %(column)s IS NULL"
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sql_create_check = "ALTER TABLE %(table)s ADD CONSTRAINT %(name)s CHECK (%(check)s)"
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sql_delete_check = "ALTER TABLE %(table)s DROP CONSTRAINT %(name)s"
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sql_create_unique = "ALTER TABLE %(table)s ADD CONSTRAINT %(name)s UNIQUE (%(columns)s)"
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sql_delete_unique = "ALTER TABLE %(table)s DROP CONSTRAINT %(name)s"
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sql_create_fk = (
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"ALTER TABLE %(table)s ADD CONSTRAINT %(name)s FOREIGN KEY (%(column)s) "
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"REFERENCES %(to_table)s (%(to_column)s)%(deferrable)s"
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)
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sql_create_inline_fk = None
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sql_delete_fk = "ALTER TABLE %(table)s DROP CONSTRAINT %(name)s"
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sql_create_index = "CREATE INDEX %(name)s ON %(table)s (%(columns)s)%(extra)s"
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sql_delete_index = "DROP INDEX %(name)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 CONSTRAINT %(name)s"
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sql_delete_procedure = 'DROP PROCEDURE %(procedure)s'
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def __init__(self, connection, collect_sql=False, atomic=True):
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self.connection = connection
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self.collect_sql = collect_sql
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if self.collect_sql:
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self.collected_sql = []
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self.atomic_migration = self.connection.features.can_rollback_ddl and atomic
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# State-managing methods
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def __enter__(self):
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self.deferred_sql = []
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if self.atomic_migration:
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self.atomic = atomic(self.connection.alias)
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self.atomic.__enter__()
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return self
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def __exit__(self, exc_type, exc_value, traceback):
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if exc_type is None:
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for sql in self.deferred_sql:
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self.execute(sql)
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if self.atomic_migration:
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self.atomic.__exit__(exc_type, exc_value, traceback)
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# Core utility functions
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def execute(self, sql, params=()):
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"""Execute the given SQL statement, with optional parameters."""
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# Don't perform the transactional DDL check if SQL is being collected
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# as it's not going to be executed anyway.
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if not self.collect_sql and self.connection.in_atomic_block and not self.connection.features.can_rollback_ddl:
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raise TransactionManagementError(
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"Executing DDL statements while in a transaction on databases "
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"that can't perform a rollback is prohibited."
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)
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# Account for non-string statement objects.
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sql = str(sql)
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# Log the command we're running, then run it
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logger.debug("%s; (params %r)", sql, params, extra={'params': params, 'sql': sql})
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if self.collect_sql:
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ending = "" if sql.endswith(";") else ";"
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if params is not None:
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self.collected_sql.append((sql % tuple(map(self.quote_value, params))) + ending)
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else:
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self.collected_sql.append(sql + ending)
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else:
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with self.connection.cursor() as cursor:
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cursor.execute(sql, params)
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def quote_name(self, name):
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return self.connection.ops.quote_name(name)
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@classmethod
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def _digest(cls, *args):
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"""
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Generate a 32-bit digest of a set of arguments that can be used to
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shorten identifying names.
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"""
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h = hashlib.md5()
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for arg in args:
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h.update(force_bytes(arg))
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return h.hexdigest()[:8]
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# Field <-> database mapping functions
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def column_sql(self, model, field, include_default=False):
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"""
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Take a field and return its column definition.
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The field must already have had set_attributes_from_name() called.
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"""
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# Get the column's type and use that as the basis of the SQL
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db_params = field.db_parameters(connection=self.connection)
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sql = db_params['type']
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params = []
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# Check for fields that aren't actually columns (e.g. M2M)
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if sql is None:
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return None, None
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# Work out nullability
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null = field.null
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# If we were told to include a default value, do so
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include_default = include_default and not self.skip_default(field)
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if include_default:
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default_value = self.effective_default(field)
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if default_value is not None:
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if self.connection.features.requires_literal_defaults:
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# Some databases can't take defaults as a parameter (oracle)
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# If this is the case, the individual schema backend should
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# implement prepare_default
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sql += " DEFAULT %s" % self.prepare_default(default_value)
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else:
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sql += " DEFAULT %s"
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params += [default_value]
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# Oracle treats the empty string ('') as null, so coerce the null
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# option whenever '' is a possible value.
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if (field.empty_strings_allowed and not field.primary_key and
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self.connection.features.interprets_empty_strings_as_nulls):
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null = True
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if null and not self.connection.features.implied_column_null:
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sql += " NULL"
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elif not null:
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sql += " NOT NULL"
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# Primary key/unique outputs
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if field.primary_key:
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sql += " PRIMARY KEY"
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elif field.unique:
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sql += " UNIQUE"
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# Optionally add the tablespace if it's an implicitly indexed column
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tablespace = field.db_tablespace or model._meta.db_tablespace
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if tablespace and self.connection.features.supports_tablespaces and field.unique:
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sql += " %s" % self.connection.ops.tablespace_sql(tablespace, inline=True)
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# Return the sql
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return sql, params
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def skip_default(self, field):
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"""
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Some backends don't accept default values for certain columns types
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(i.e. MySQL longtext and longblob).
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"""
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return False
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def prepare_default(self, value):
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"""
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Only used for backends which have requires_literal_defaults feature
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"""
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raise NotImplementedError(
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'subclasses of BaseDatabaseSchemaEditor for backends which have '
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'requires_literal_defaults must provide a prepare_default() method'
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)
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def effective_default(self, field):
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"""Return a field's effective database default value."""
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if field.has_default():
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default = field.get_default()
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elif not field.null and field.blank and field.empty_strings_allowed:
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if field.get_internal_type() == "BinaryField":
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default = bytes()
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else:
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default = str()
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elif getattr(field, 'auto_now', False) or getattr(field, 'auto_now_add', False):
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default = datetime.now()
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internal_type = field.get_internal_type()
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if internal_type == 'DateField':
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default = default.date
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elif internal_type == 'TimeField':
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default = default.time
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elif internal_type == 'DateTimeField':
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default = timezone.now
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else:
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default = None
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# If it's a callable, call it
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if callable(default):
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default = default()
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# Convert the value so it can be sent to the database.
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return field.get_db_prep_save(default, self.connection)
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def quote_value(self, value):
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"""
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Return a quoted version of the value so it's safe to use in an SQL
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string. This is not safe against injection from user code; it is
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intended only for use in making SQL scripts or preparing default values
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for particularly tricky backends (defaults are not user-defined, though,
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so this is safe).
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"""
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raise NotImplementedError()
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# Actions
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def create_model(self, model):
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"""
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Create a table and any accompanying indexes or unique constraints for
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the given `model`.
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"""
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# Create column SQL, add FK deferreds if needed
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column_sqls = []
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params = []
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for field in model._meta.local_fields:
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# SQL
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definition, extra_params = self.column_sql(model, field)
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if definition is None:
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continue
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# Check constraints can go on the column SQL here
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db_params = field.db_parameters(connection=self.connection)
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if db_params['check']:
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definition += " CHECK (%s)" % db_params['check']
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# Autoincrement SQL (for backends with inline variant)
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col_type_suffix = field.db_type_suffix(connection=self.connection)
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if col_type_suffix:
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definition += " %s" % col_type_suffix
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params.extend(extra_params)
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# FK
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if field.remote_field and field.db_constraint:
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to_table = field.remote_field.model._meta.db_table
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to_column = field.remote_field.model._meta.get_field(field.remote_field.field_name).column
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if self.sql_create_inline_fk:
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definition += " " + self.sql_create_inline_fk % {
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"to_table": self.quote_name(to_table),
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"to_column": self.quote_name(to_column),
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}
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elif self.connection.features.supports_foreign_keys:
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self.deferred_sql.append(self._create_fk_sql(model, field, "_fk_%(to_table)s_%(to_column)s"))
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# Add the SQL to our big list
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column_sqls.append("%s %s" % (
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self.quote_name(field.column),
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definition,
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))
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# Autoincrement SQL (for backends with post table definition variant)
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if field.get_internal_type() in ("AutoField", "BigAutoField"):
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autoinc_sql = self.connection.ops.autoinc_sql(model._meta.db_table, field.column)
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if autoinc_sql:
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self.deferred_sql.extend(autoinc_sql)
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# Add any unique_togethers (always deferred, as some fields might be
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# created afterwards, like geometry fields with some backends)
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for fields in model._meta.unique_together:
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columns = [model._meta.get_field(field).column for field in fields]
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self.deferred_sql.append(self._create_unique_sql(model, columns))
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# Make the table
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sql = self.sql_create_table % {
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"table": self.quote_name(model._meta.db_table),
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"definition": ", ".join(column_sqls)
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}
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if model._meta.db_tablespace:
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tablespace_sql = self.connection.ops.tablespace_sql(model._meta.db_tablespace)
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if tablespace_sql:
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sql += ' ' + tablespace_sql
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# Prevent using [] as params, in the case a literal '%' is used in the definition
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self.execute(sql, params or None)
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# Add any field index and index_together's (deferred as SQLite3 _remake_table needs it)
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self.deferred_sql.extend(self._model_indexes_sql(model))
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# Make M2M tables
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for field in model._meta.local_many_to_many:
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if field.remote_field.through._meta.auto_created:
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self.create_model(field.remote_field.through)
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def delete_model(self, model):
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"""Delete a model from the database."""
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# Handle auto-created intermediary models
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for field in model._meta.local_many_to_many:
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if field.remote_field.through._meta.auto_created:
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self.delete_model(field.remote_field.through)
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# Delete the table
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self.execute(self.sql_delete_table % {
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"table": self.quote_name(model._meta.db_table),
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})
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# Remove all deferred statements referencing the deleted table.
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for sql in list(self.deferred_sql):
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if isinstance(sql, Statement) and sql.references_table(model._meta.db_table):
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self.deferred_sql.remove(sql)
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def add_index(self, model, index):
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"""Add an index on a model."""
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self.execute(index.create_sql(model, self))
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def remove_index(self, model, index):
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"""Remove an index from a model."""
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self.execute(index.remove_sql(model, self))
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def alter_unique_together(self, model, old_unique_together, new_unique_together):
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"""
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Deal with a model changing its unique_together. The input
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unique_togethers must be doubly-nested, not the single-nested
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["foo", "bar"] format.
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"""
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olds = {tuple(fields) for fields in old_unique_together}
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news = {tuple(fields) for fields in new_unique_together}
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# Deleted uniques
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for fields in olds.difference(news):
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self._delete_composed_index(model, fields, {'unique': True}, self.sql_delete_unique)
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# Created uniques
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for fields in news.difference(olds):
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columns = [model._meta.get_field(field).column for field in fields]
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self.execute(self._create_unique_sql(model, columns))
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def alter_index_together(self, model, old_index_together, new_index_together):
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"""
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Deal with a model changing its index_together. The input
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index_togethers must be doubly-nested, not the single-nested
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["foo", "bar"] format.
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"""
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olds = {tuple(fields) for fields in old_index_together}
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news = {tuple(fields) for fields in new_index_together}
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# Deleted indexes
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for fields in olds.difference(news):
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self._delete_composed_index(model, fields, {'index': True}, self.sql_delete_index)
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# Created indexes
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for field_names in news.difference(olds):
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fields = [model._meta.get_field(field) for field in field_names]
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self.execute(self._create_index_sql(model, fields, suffix="_idx"))
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def _delete_composed_index(self, model, fields, constraint_kwargs, sql):
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columns = [model._meta.get_field(field).column for field in fields]
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constraint_names = self._constraint_names(model, columns, **constraint_kwargs)
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if len(constraint_names) != 1:
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raise ValueError("Found wrong number (%s) of constraints for %s(%s)" % (
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len(constraint_names),
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model._meta.db_table,
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", ".join(columns),
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))
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self.execute(self._delete_constraint_sql(sql, model, constraint_names[0]))
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def alter_db_table(self, model, old_db_table, new_db_table):
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"""Rename the table a model points to."""
|
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if (old_db_table == new_db_table or
|
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(self.connection.features.ignores_table_name_case and
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old_db_table.lower() == new_db_table.lower())):
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return
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self.execute(self.sql_rename_table % {
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"old_table": self.quote_name(old_db_table),
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"new_table": self.quote_name(new_db_table),
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})
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# Rename all references to the old table name.
|
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for sql in self.deferred_sql:
|
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if isinstance(sql, Statement):
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sql.rename_table_references(old_db_table, new_db_table)
|
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|
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def alter_db_tablespace(self, model, old_db_tablespace, new_db_tablespace):
|
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"""Move a model's table between tablespaces."""
|
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self.execute(self.sql_retablespace_table % {
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"table": self.quote_name(model._meta.db_table),
|
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"old_tablespace": self.quote_name(old_db_tablespace),
|
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"new_tablespace": self.quote_name(new_db_tablespace),
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})
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|
|
def add_field(self, model, field):
|
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"""
|
|
Create a field on a model. Usually involves adding a column, but may
|
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involve adding a table instead (for M2M fields).
|
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"""
|
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# Special-case implicit M2M tables
|
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if field.many_to_many and field.remote_field.through._meta.auto_created:
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return self.create_model(field.remote_field.through)
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# Get the column's definition
|
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definition, params = self.column_sql(model, field, include_default=True)
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# It might not actually have a column behind it
|
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if definition is None:
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return
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# Check constraints can go on the column SQL here
|
|
db_params = field.db_parameters(connection=self.connection)
|
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if db_params['check']:
|
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definition += " CHECK (%s)" % db_params['check']
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# Build the SQL and run it
|
|
sql = self.sql_create_column % {
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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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"definition": definition,
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}
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self.execute(sql, params)
|
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# Drop the default if we need to
|
|
# (Django usually does not use in-database defaults)
|
|
if not self.skip_default(field) and self.effective_default(field) is not None:
|
|
changes_sql, params = self._alter_column_default_sql(model, None, field, drop=True)
|
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sql = self.sql_alter_column % {
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"table": self.quote_name(model._meta.db_table),
|
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"changes": changes_sql,
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}
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self.execute(sql, params)
|
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# Add an index, if required
|
|
self.deferred_sql.extend(self._field_indexes_sql(model, field))
|
|
# Add any FK constraints later
|
|
if field.remote_field and self.connection.features.supports_foreign_keys and field.db_constraint:
|
|
self.deferred_sql.append(self._create_fk_sql(model, field, "_fk_%(to_table)s_%(to_column)s"))
|
|
# Reset connection if required
|
|
if self.connection.features.connection_persists_old_columns:
|
|
self.connection.close()
|
|
|
|
def remove_field(self, model, field):
|
|
"""
|
|
Remove a field from a model. Usually involves deleting a column,
|
|
but for M2Ms may involve deleting a table.
|
|
"""
|
|
# Special-case implicit M2M tables
|
|
if field.many_to_many and field.remote_field.through._meta.auto_created:
|
|
return self.delete_model(field.remote_field.through)
|
|
# It might not actually have a column behind it
|
|
if field.db_parameters(connection=self.connection)['type'] is None:
|
|
return
|
|
# Drop any FK constraints, MySQL requires explicit deletion
|
|
if field.remote_field:
|
|
fk_names = self._constraint_names(model, [field.column], foreign_key=True)
|
|
for fk_name in fk_names:
|
|
self.execute(self._delete_constraint_sql(self.sql_delete_fk, model, fk_name))
|
|
# Delete the column
|
|
sql = self.sql_delete_column % {
|
|
"table": self.quote_name(model._meta.db_table),
|
|
"column": self.quote_name(field.column),
|
|
}
|
|
self.execute(sql)
|
|
# Reset connection if required
|
|
if self.connection.features.connection_persists_old_columns:
|
|
self.connection.close()
|
|
# Remove all deferred statements referencing the deleted column.
|
|
for sql in list(self.deferred_sql):
|
|
if isinstance(sql, Statement) and sql.references_column(model._meta.db_table, field.column):
|
|
self.deferred_sql.remove(sql)
|
|
|
|
def alter_field(self, model, old_field, new_field, strict=False):
|
|
"""
|
|
Allow a field's type, uniqueness, nullability, default, column,
|
|
constraints, etc. to be modified.
|
|
`old_field` is required to compute the necessary changes.
|
|
If `strict` is True, raise errors if the old column does not match
|
|
`old_field` precisely.
|
|
"""
|
|
# Ensure this field is even column-based
|
|
old_db_params = old_field.db_parameters(connection=self.connection)
|
|
old_type = old_db_params['type']
|
|
new_db_params = new_field.db_parameters(connection=self.connection)
|
|
new_type = new_db_params['type']
|
|
if ((old_type is None and old_field.remote_field is None) or
|
|
(new_type is None and new_field.remote_field is None)):
|
|
raise ValueError(
|
|
"Cannot alter field %s into %s - they do not properly define "
|
|
"db_type (are you using a badly-written custom field?)" %
|
|
(old_field, new_field),
|
|
)
|
|
elif old_type is None and new_type is None and (
|
|
old_field.remote_field.through and new_field.remote_field.through and
|
|
old_field.remote_field.through._meta.auto_created and
|
|
new_field.remote_field.through._meta.auto_created):
|
|
return self._alter_many_to_many(model, old_field, new_field, strict)
|
|
elif old_type is None and new_type is None and (
|
|
old_field.remote_field.through and new_field.remote_field.through and
|
|
not old_field.remote_field.through._meta.auto_created and
|
|
not new_field.remote_field.through._meta.auto_created):
|
|
# Both sides have through models; this is a no-op.
|
|
return
|
|
elif old_type is None or new_type is None:
|
|
raise ValueError(
|
|
"Cannot alter field %s into %s - they are not compatible types "
|
|
"(you cannot alter to or from M2M fields, or add or remove "
|
|
"through= on M2M fields)" % (old_field, new_field)
|
|
)
|
|
|
|
self._alter_field(model, old_field, new_field, old_type, new_type,
|
|
old_db_params, new_db_params, strict)
|
|
|
|
def _alter_field(self, model, old_field, new_field, old_type, new_type,
|
|
old_db_params, new_db_params, strict=False):
|
|
"""Perform a "physical" (non-ManyToMany) field update."""
|
|
# Drop any FK constraints, we'll remake them later
|
|
fks_dropped = set()
|
|
if old_field.remote_field and old_field.db_constraint:
|
|
fk_names = self._constraint_names(model, [old_field.column], foreign_key=True)
|
|
if strict and len(fk_names) != 1:
|
|
raise ValueError("Found wrong number (%s) of foreign key constraints for %s.%s" % (
|
|
len(fk_names),
|
|
model._meta.db_table,
|
|
old_field.column,
|
|
))
|
|
for fk_name in fk_names:
|
|
fks_dropped.add((old_field.column,))
|
|
self.execute(self._delete_constraint_sql(self.sql_delete_fk, model, fk_name))
|
|
# Has unique been removed?
|
|
if old_field.unique and (not new_field.unique or self._field_became_primary_key(old_field, new_field)):
|
|
# Find the unique constraint for this field
|
|
constraint_names = self._constraint_names(model, [old_field.column], unique=True, primary_key=False)
|
|
if strict and len(constraint_names) != 1:
|
|
raise ValueError("Found wrong number (%s) of unique constraints for %s.%s" % (
|
|
len(constraint_names),
|
|
model._meta.db_table,
|
|
old_field.column,
|
|
))
|
|
for constraint_name in constraint_names:
|
|
self.execute(self._delete_constraint_sql(self.sql_delete_unique, model, constraint_name))
|
|
# Drop incoming FK constraints if the field is a primary key or unique,
|
|
# which might be a to_field target, and things are going to change.
|
|
drop_foreign_keys = (
|
|
(
|
|
(old_field.primary_key and new_field.primary_key) or
|
|
(old_field.unique and new_field.unique)
|
|
) and old_type != new_type
|
|
)
|
|
if drop_foreign_keys:
|
|
# '_meta.related_field' also contains M2M reverse fields, these
|
|
# will be filtered out
|
|
for _old_rel, new_rel in _related_non_m2m_objects(old_field, new_field):
|
|
rel_fk_names = self._constraint_names(
|
|
new_rel.related_model, [new_rel.field.column], foreign_key=True
|
|
)
|
|
for fk_name in rel_fk_names:
|
|
self.execute(self._delete_constraint_sql(self.sql_delete_fk, new_rel.related_model, fk_name))
|
|
# Removed an index? (no strict check, as multiple indexes are possible)
|
|
# Remove indexes if db_index switched to False or a unique constraint
|
|
# will now be used in lieu of an index. The following lines from the
|
|
# truth table show all True cases; the rest are False:
|
|
#
|
|
# old_field.db_index | old_field.unique | new_field.db_index | new_field.unique
|
|
# ------------------------------------------------------------------------------
|
|
# True | False | False | False
|
|
# True | False | False | True
|
|
# True | False | True | True
|
|
if old_field.db_index and not old_field.unique and (not new_field.db_index or new_field.unique):
|
|
# Find the index for this field
|
|
meta_index_names = {index.name for index in model._meta.indexes}
|
|
# Retrieve only BTREE indexes since this is what's created with
|
|
# db_index=True.
|
|
index_names = self._constraint_names(model, [old_field.column], index=True, type_=Index.suffix)
|
|
for index_name in index_names:
|
|
if index_name not in meta_index_names:
|
|
# The only way to check if an index was created with
|
|
# db_index=True or with Index(['field'], name='foo')
|
|
# is to look at its name (refs #28053).
|
|
self.execute(self._delete_constraint_sql(self.sql_delete_index, model, index_name))
|
|
# Change check constraints?
|
|
if old_db_params['check'] != new_db_params['check'] and old_db_params['check']:
|
|
constraint_names = self._constraint_names(model, [old_field.column], check=True)
|
|
if strict and len(constraint_names) != 1:
|
|
raise ValueError("Found wrong number (%s) of check constraints for %s.%s" % (
|
|
len(constraint_names),
|
|
model._meta.db_table,
|
|
old_field.column,
|
|
))
|
|
for constraint_name in constraint_names:
|
|
self.execute(self._delete_constraint_sql(self.sql_delete_check, model, constraint_name))
|
|
# Have they renamed the column?
|
|
if old_field.column != new_field.column:
|
|
self.execute(self._rename_field_sql(model._meta.db_table, old_field, new_field, new_type))
|
|
# Rename all references to the renamed column.
|
|
for sql in self.deferred_sql:
|
|
if isinstance(sql, Statement):
|
|
sql.rename_column_references(model._meta.db_table, old_field.column, new_field.column)
|
|
# Next, start accumulating actions to do
|
|
actions = []
|
|
null_actions = []
|
|
post_actions = []
|
|
# Type change?
|
|
if old_type != new_type:
|
|
fragment, other_actions = self._alter_column_type_sql(model, old_field, new_field, new_type)
|
|
actions.append(fragment)
|
|
post_actions.extend(other_actions)
|
|
# When changing a column NULL constraint to NOT NULL with a given
|
|
# default value, we need to perform 4 steps:
|
|
# 1. Add a default for new incoming writes
|
|
# 2. Update existing NULL rows with new default
|
|
# 3. Replace NULL constraint with NOT NULL
|
|
# 4. Drop the default again.
|
|
# Default change?
|
|
old_default = self.effective_default(old_field)
|
|
new_default = self.effective_default(new_field)
|
|
needs_database_default = (
|
|
old_field.null and
|
|
not new_field.null and
|
|
old_default != new_default and
|
|
new_default is not None and
|
|
not self.skip_default(new_field)
|
|
)
|
|
if needs_database_default:
|
|
actions.append(self._alter_column_default_sql(model, old_field, new_field))
|
|
# Nullability change?
|
|
if old_field.null != new_field.null:
|
|
fragment = self._alter_column_null_sql(model, old_field, new_field)
|
|
if fragment:
|
|
null_actions.append(fragment)
|
|
# Only if we have a default and there is a change from NULL to NOT NULL
|
|
four_way_default_alteration = (
|
|
new_field.has_default() and
|
|
(old_field.null and not new_field.null)
|
|
)
|
|
if actions or null_actions:
|
|
if not four_way_default_alteration:
|
|
# If we don't have to do a 4-way default alteration we can
|
|
# directly run a (NOT) NULL alteration
|
|
actions = actions + null_actions
|
|
# Combine actions together if we can (e.g. postgres)
|
|
if self.connection.features.supports_combined_alters and actions:
|
|
sql, params = tuple(zip(*actions))
|
|
actions = [(", ".join(sql), sum(params, []))]
|
|
# Apply those actions
|
|
for sql, params in actions:
|
|
self.execute(
|
|
self.sql_alter_column % {
|
|
"table": self.quote_name(model._meta.db_table),
|
|
"changes": sql,
|
|
},
|
|
params,
|
|
)
|
|
if four_way_default_alteration:
|
|
# Update existing rows with default value
|
|
self.execute(
|
|
self.sql_update_with_default % {
|
|
"table": self.quote_name(model._meta.db_table),
|
|
"column": self.quote_name(new_field.column),
|
|
"default": "%s",
|
|
},
|
|
[new_default],
|
|
)
|
|
# Since we didn't run a NOT NULL change before we need to do it
|
|
# now
|
|
for sql, params in null_actions:
|
|
self.execute(
|
|
self.sql_alter_column % {
|
|
"table": self.quote_name(model._meta.db_table),
|
|
"changes": sql,
|
|
},
|
|
params,
|
|
)
|
|
if post_actions:
|
|
for sql, params in post_actions:
|
|
self.execute(sql, params)
|
|
# If primary_key changed to False, delete the primary key constraint.
|
|
if old_field.primary_key and not new_field.primary_key:
|
|
self._delete_primary_key(model, strict)
|
|
# Added a unique?
|
|
if self._unique_should_be_added(old_field, new_field):
|
|
self.execute(self._create_unique_sql(model, [new_field.column]))
|
|
# Added an index? Add an index if db_index switched to True or a unique
|
|
# constraint will no longer be used in lieu of an index. The following
|
|
# lines from the truth table show all True cases; the rest are False:
|
|
#
|
|
# old_field.db_index | old_field.unique | new_field.db_index | new_field.unique
|
|
# ------------------------------------------------------------------------------
|
|
# False | False | True | False
|
|
# False | True | True | False
|
|
# True | True | True | False
|
|
if (not old_field.db_index or old_field.unique) and new_field.db_index and not new_field.unique:
|
|
self.execute(self._create_index_sql(model, [new_field]))
|
|
# Type alteration on primary key? Then we need to alter the column
|
|
# referring to us.
|
|
rels_to_update = []
|
|
if old_field.primary_key and new_field.primary_key and old_type != new_type:
|
|
rels_to_update.extend(_related_non_m2m_objects(old_field, new_field))
|
|
# Changed to become primary key?
|
|
if self._field_became_primary_key(old_field, new_field):
|
|
# Make the new one
|
|
self.execute(
|
|
self.sql_create_pk % {
|
|
"table": self.quote_name(model._meta.db_table),
|
|
"name": self.quote_name(
|
|
self._create_index_name(model._meta.db_table, [new_field.column], suffix="_pk")
|
|
),
|
|
"columns": self.quote_name(new_field.column),
|
|
}
|
|
)
|
|
# Update all referencing columns
|
|
rels_to_update.extend(_related_non_m2m_objects(old_field, new_field))
|
|
# Handle our type alters on the other end of rels from the PK stuff above
|
|
for old_rel, new_rel in rels_to_update:
|
|
rel_db_params = new_rel.field.db_parameters(connection=self.connection)
|
|
rel_type = rel_db_params['type']
|
|
fragment, other_actions = self._alter_column_type_sql(
|
|
new_rel.related_model, old_rel.field, new_rel.field, rel_type
|
|
)
|
|
self.execute(
|
|
self.sql_alter_column % {
|
|
"table": self.quote_name(new_rel.related_model._meta.db_table),
|
|
"changes": fragment[0],
|
|
},
|
|
fragment[1],
|
|
)
|
|
for sql, params in other_actions:
|
|
self.execute(sql, params)
|
|
# Does it have a foreign key?
|
|
if (new_field.remote_field and
|
|
(fks_dropped or not old_field.remote_field or not old_field.db_constraint) and
|
|
new_field.db_constraint):
|
|
self.execute(self._create_fk_sql(model, new_field, "_fk_%(to_table)s_%(to_column)s"))
|
|
# Rebuild FKs that pointed to us if we previously had to drop them
|
|
if drop_foreign_keys:
|
|
for rel in new_field.model._meta.related_objects:
|
|
if _is_relevant_relation(rel, new_field) and rel.field.db_constraint:
|
|
self.execute(self._create_fk_sql(rel.related_model, rel.field, "_fk"))
|
|
# Does it have check constraints we need to add?
|
|
if old_db_params['check'] != new_db_params['check'] and new_db_params['check']:
|
|
self.execute(
|
|
self.sql_create_check % {
|
|
"table": self.quote_name(model._meta.db_table),
|
|
"name": self.quote_name(
|
|
self._create_index_name(model._meta.db_table, [new_field.column], suffix="_check")
|
|
),
|
|
"column": self.quote_name(new_field.column),
|
|
"check": new_db_params['check'],
|
|
}
|
|
)
|
|
# Drop the default if we need to
|
|
# (Django usually does not use in-database defaults)
|
|
if needs_database_default:
|
|
changes_sql, params = self._alter_column_default_sql(model, old_field, new_field, drop=True)
|
|
sql = self.sql_alter_column % {
|
|
"table": self.quote_name(model._meta.db_table),
|
|
"changes": changes_sql,
|
|
}
|
|
self.execute(sql, params)
|
|
# Reset connection if required
|
|
if self.connection.features.connection_persists_old_columns:
|
|
self.connection.close()
|
|
|
|
def _alter_column_null_sql(self, model, old_field, new_field):
|
|
"""
|
|
Hook to specialize column null alteration.
|
|
|
|
Return a (sql, params) fragment to set a column to null or non-null
|
|
as required by new_field, or None if no changes are required.
|
|
"""
|
|
if (self.connection.features.interprets_empty_strings_as_nulls and
|
|
new_field.get_internal_type() in ("CharField", "TextField")):
|
|
# The field is nullable in the database anyway, leave it alone.
|
|
return
|
|
else:
|
|
new_db_params = new_field.db_parameters(connection=self.connection)
|
|
sql = self.sql_alter_column_null if new_field.null else self.sql_alter_column_not_null
|
|
return (
|
|
sql % {
|
|
'column': self.quote_name(new_field.column),
|
|
'type': new_db_params['type'],
|
|
},
|
|
[],
|
|
)
|
|
|
|
def _alter_column_default_sql(self, model, old_field, new_field, drop=False):
|
|
"""
|
|
Hook to specialize column default alteration.
|
|
|
|
Return a (sql, params) fragment to add or drop (depending on the drop
|
|
argument) a default to new_field's column.
|
|
"""
|
|
new_default = self.effective_default(new_field)
|
|
default = '%s'
|
|
params = [new_default]
|
|
|
|
if drop:
|
|
params = []
|
|
elif self.connection.features.requires_literal_defaults:
|
|
# Some databases (Oracle) can't take defaults as a parameter
|
|
# If this is the case, the SchemaEditor for that database should
|
|
# implement prepare_default().
|
|
default = self.prepare_default(new_default)
|
|
params = []
|
|
|
|
new_db_params = new_field.db_parameters(connection=self.connection)
|
|
sql = self.sql_alter_column_no_default if drop else self.sql_alter_column_default
|
|
return (
|
|
sql % {
|
|
'column': self.quote_name(new_field.column),
|
|
'type': new_db_params['type'],
|
|
'default': default,
|
|
},
|
|
params,
|
|
)
|
|
|
|
def _alter_column_type_sql(self, model, old_field, new_field, new_type):
|
|
"""
|
|
Hook to specialize column type alteration for different backends,
|
|
for cases when a creation type is different to an alteration type
|
|
(e.g. SERIAL in PostgreSQL, PostGIS fields).
|
|
|
|
Return a two-tuple of: an SQL fragment of (sql, params) to insert into
|
|
an ALTER TABLE statement and a list of extra (sql, params) tuples to
|
|
run once the field is altered.
|
|
"""
|
|
return (
|
|
(
|
|
self.sql_alter_column_type % {
|
|
"column": self.quote_name(new_field.column),
|
|
"type": new_type,
|
|
},
|
|
[],
|
|
),
|
|
[],
|
|
)
|
|
|
|
def _alter_many_to_many(self, model, old_field, new_field, strict):
|
|
"""Alter M2Ms to repoint their to= endpoints."""
|
|
# Rename the through table
|
|
if old_field.remote_field.through._meta.db_table != new_field.remote_field.through._meta.db_table:
|
|
self.alter_db_table(old_field.remote_field.through, old_field.remote_field.through._meta.db_table,
|
|
new_field.remote_field.through._meta.db_table)
|
|
# Repoint the FK to the other side
|
|
self.alter_field(
|
|
new_field.remote_field.through,
|
|
# We need the field that points to the target model, so we can tell alter_field to change it -
|
|
# this is m2m_reverse_field_name() (as opposed to m2m_field_name, which points to our model)
|
|
old_field.remote_field.through._meta.get_field(old_field.m2m_reverse_field_name()),
|
|
new_field.remote_field.through._meta.get_field(new_field.m2m_reverse_field_name()),
|
|
)
|
|
self.alter_field(
|
|
new_field.remote_field.through,
|
|
# for self-referential models we need to alter field from the other end too
|
|
old_field.remote_field.through._meta.get_field(old_field.m2m_field_name()),
|
|
new_field.remote_field.through._meta.get_field(new_field.m2m_field_name()),
|
|
)
|
|
|
|
def _create_index_name(self, table_name, column_names, suffix=""):
|
|
"""
|
|
Generate a unique name for an index/unique constraint.
|
|
|
|
The name is divided into 3 parts: the table name, the column names,
|
|
and a unique digest and suffix.
|
|
"""
|
|
_, table_name = split_identifier(table_name)
|
|
hash_suffix_part = '%s%s' % (self._digest(table_name, *column_names), suffix)
|
|
max_length = self.connection.ops.max_name_length() or 200
|
|
# If everything fits into max_length, use that name.
|
|
index_name = '%s_%s_%s' % (table_name, '_'.join(column_names), hash_suffix_part)
|
|
if len(index_name) <= max_length:
|
|
return index_name
|
|
# Shorten a long suffix.
|
|
if len(hash_suffix_part) > max_length / 3:
|
|
hash_suffix_part = hash_suffix_part[:max_length // 3]
|
|
other_length = (max_length - len(hash_suffix_part)) // 2 - 1
|
|
index_name = '%s_%s_%s' % (
|
|
table_name[:other_length],
|
|
'_'.join(column_names)[:other_length],
|
|
hash_suffix_part,
|
|
)
|
|
# Prepend D if needed to prevent the name from starting with an
|
|
# underscore or a number (not permitted on Oracle).
|
|
if index_name[0] == "_" or index_name[0].isdigit():
|
|
index_name = "D%s" % index_name[:-1]
|
|
return index_name
|
|
|
|
def _get_index_tablespace_sql(self, model, fields, db_tablespace=None):
|
|
if db_tablespace is None:
|
|
if len(fields) == 1 and fields[0].db_tablespace:
|
|
db_tablespace = fields[0].db_tablespace
|
|
elif model._meta.db_tablespace:
|
|
db_tablespace = model._meta.db_tablespace
|
|
if db_tablespace is not None:
|
|
return ' ' + self.connection.ops.tablespace_sql(db_tablespace)
|
|
return ''
|
|
|
|
def _create_index_sql(self, model, fields, *, name=None, suffix='', using='',
|
|
db_tablespace=None, col_suffixes=(), sql=None):
|
|
"""
|
|
Return the SQL statement to create the index for one or several fields.
|
|
`sql` can be specified if the syntax differs from the standard (GIS
|
|
indexes, ...).
|
|
"""
|
|
tablespace_sql = self._get_index_tablespace_sql(model, fields, db_tablespace=db_tablespace)
|
|
columns = [field.column for field in fields]
|
|
sql_create_index = sql or self.sql_create_index
|
|
table = model._meta.db_table
|
|
|
|
def create_index_name(*args, **kwargs):
|
|
nonlocal name
|
|
if name is None:
|
|
name = self._create_index_name(*args, **kwargs)
|
|
return self.quote_name(name)
|
|
|
|
return Statement(
|
|
sql_create_index,
|
|
table=Table(table, self.quote_name),
|
|
name=IndexName(table, columns, suffix, create_index_name),
|
|
using=using,
|
|
columns=Columns(table, columns, self.quote_name, col_suffixes=col_suffixes),
|
|
extra=tablespace_sql,
|
|
)
|
|
|
|
def _model_indexes_sql(self, model):
|
|
"""
|
|
Return a list of all index SQL statements (field indexes,
|
|
index_together, Meta.indexes) for the specified model.
|
|
"""
|
|
if not model._meta.managed or model._meta.proxy or model._meta.swapped:
|
|
return []
|
|
output = []
|
|
for field in model._meta.local_fields:
|
|
output.extend(self._field_indexes_sql(model, field))
|
|
|
|
for field_names in model._meta.index_together:
|
|
fields = [model._meta.get_field(field) for field in field_names]
|
|
output.append(self._create_index_sql(model, fields, suffix="_idx"))
|
|
|
|
for index in model._meta.indexes:
|
|
output.append(index.create_sql(model, self))
|
|
return output
|
|
|
|
def _field_indexes_sql(self, model, field):
|
|
"""
|
|
Return a list of all index SQL statements for the specified field.
|
|
"""
|
|
output = []
|
|
if self._field_should_be_indexed(model, field):
|
|
output.append(self._create_index_sql(model, [field]))
|
|
return output
|
|
|
|
def _field_should_be_indexed(self, model, field):
|
|
return field.db_index and not field.unique
|
|
|
|
def _field_became_primary_key(self, old_field, new_field):
|
|
return not old_field.primary_key and new_field.primary_key
|
|
|
|
def _unique_should_be_added(self, old_field, new_field):
|
|
return (not old_field.unique and new_field.unique) or (
|
|
old_field.primary_key and not new_field.primary_key and new_field.unique
|
|
)
|
|
|
|
def _rename_field_sql(self, table, old_field, new_field, new_type):
|
|
return self.sql_rename_column % {
|
|
"table": self.quote_name(table),
|
|
"old_column": self.quote_name(old_field.column),
|
|
"new_column": self.quote_name(new_field.column),
|
|
"type": new_type,
|
|
}
|
|
|
|
def _create_fk_sql(self, model, field, suffix):
|
|
from_table = model._meta.db_table
|
|
from_column = field.column
|
|
_, to_table = split_identifier(field.target_field.model._meta.db_table)
|
|
to_column = field.target_field.column
|
|
|
|
def create_fk_name(*args, **kwargs):
|
|
return self.quote_name(self._create_index_name(*args, **kwargs))
|
|
|
|
return Statement(
|
|
self.sql_create_fk,
|
|
table=Table(from_table, self.quote_name),
|
|
name=ForeignKeyName(from_table, [from_column], to_table, [to_column], suffix, create_fk_name),
|
|
column=Columns(from_table, [from_column], self.quote_name),
|
|
to_table=Table(field.target_field.model._meta.db_table, self.quote_name),
|
|
to_column=Columns(field.target_field.model._meta.db_table, [to_column], self.quote_name),
|
|
deferrable=self.connection.ops.deferrable_sql(),
|
|
)
|
|
|
|
def _create_unique_sql(self, model, columns):
|
|
def create_unique_name(*args, **kwargs):
|
|
return self.quote_name(self._create_index_name(*args, **kwargs))
|
|
table = model._meta.db_table
|
|
return Statement(
|
|
self.sql_create_unique,
|
|
table=Table(table, self.quote_name),
|
|
name=IndexName(table, columns, '_uniq', create_unique_name),
|
|
columns=Columns(table, columns, self.quote_name),
|
|
)
|
|
|
|
def _delete_constraint_sql(self, template, model, name):
|
|
return template % {
|
|
"table": self.quote_name(model._meta.db_table),
|
|
"name": self.quote_name(name),
|
|
}
|
|
|
|
def _constraint_names(self, model, column_names=None, unique=None,
|
|
primary_key=None, index=None, foreign_key=None,
|
|
check=None, type_=None):
|
|
"""Return all constraint names matching the columns and conditions."""
|
|
if column_names is not None:
|
|
column_names = [
|
|
self.connection.introspection.column_name_converter(name)
|
|
for name in column_names
|
|
]
|
|
with self.connection.cursor() as cursor:
|
|
constraints = self.connection.introspection.get_constraints(cursor, model._meta.db_table)
|
|
result = []
|
|
for name, infodict in constraints.items():
|
|
if column_names is None or column_names == infodict['columns']:
|
|
if unique is not None and infodict['unique'] != unique:
|
|
continue
|
|
if primary_key is not None and infodict['primary_key'] != primary_key:
|
|
continue
|
|
if index is not None and infodict['index'] != index:
|
|
continue
|
|
if check is not None and infodict['check'] != check:
|
|
continue
|
|
if foreign_key is not None and not infodict['foreign_key']:
|
|
continue
|
|
if type_ is not None and infodict['type'] != type_:
|
|
continue
|
|
result.append(name)
|
|
return result
|
|
|
|
def _delete_primary_key(self, model, strict=False):
|
|
constraint_names = self._constraint_names(model, primary_key=True)
|
|
if strict and len(constraint_names) != 1:
|
|
raise ValueError('Found wrong number (%s) of PK constraints for %s' % (
|
|
len(constraint_names),
|
|
model._meta.db_table,
|
|
))
|
|
for constraint_name in constraint_names:
|
|
self.execute(self._delete_constraint_sql(self.sql_delete_pk, model, constraint_name))
|
|
|
|
def remove_procedure(self, procedure_name, param_types=()):
|
|
sql = self.sql_delete_procedure % {
|
|
'procedure': self.quote_name(procedure_name),
|
|
'param_types': ','.join(param_types),
|
|
}
|
|
self.execute(sql)
|