django.db.migrations.operations.base.Operation

class documentation

class Operation:

Known subclasses: django.contrib.postgres.operations.CreateExtension, django.contrib.postgres.operations.ValidateConstraint, django.db.migrations.operations.RunPython, django.db.migrations.operations.RunSQL, django.db.migrations.operations.SeparateDatabaseAndState, django.contrib.postgres.operations.CollationOperation, django.db.migrations.operations.fields.FieldOperation, django.db.migrations.operations.models.IndexOperation, django.db.migrations.operations.models.ModelOperation

View In Hierarchy

Base class for migration operations.

It's responsible for both mutating the in-memory model state (see db/migrations/state.py) to represent what it performs, as well as actually performing it against a live database.

Note that some operations won't modify memory state at all (e.g. data copying operations), and some will need their modifications to be optionally specified by the user (e.g. custom Python code snippets)

Due to the way this class deals with deconstruction, it should be considered immutable.

Method __new__ Undocumented
Method __repr__ Undocumented
Method allow​_migrate​_model Return whether or not a model may be migrated.
Method database​_backwards Perform the mutation on the database schema in the reverse direction - e.g. if this were CreateModel, it would in fact drop the model's table.
Method database​_forwards Perform the mutation on the database schema in the normal (forwards) direction.
Method deconstruct Return a 3-tuple of class import path (or just name if it lives under django.db.migrations), positional arguments, and keyword arguments.
Method describe Output a brief summary of what the action does.
Method reduce Return either a list of operations the actual operation should be replaced with or a boolean that indicates whether or not the specified operation can be optimized across.
Method references​_field Return True if there is a chance this operation references the given field name, with an app label for accuracy.
Method references​_model Return True if there is a chance this operation references the given model name (as a string), with an app label for accuracy.
Method state​_forwards Take the state from the previous migration, and mutate it so that it matches what this migration would perform.
Class Variable atomic Undocumented
Class Variable elidable Undocumented
Class Variable reduces​_to​_sql Undocumented
Class Variable reversible Undocumented
Class Variable serialization​_expand​_args Undocumented
Instance Variable ​_constructor​_args Undocumented
Property migration​_name​_fragment A filename part suitable for automatically naming a migration containing this operation, or None if not applicable.
def __new__(cls, *args, **kwargs):

Undocumented

def __repr__(self):

Undocumented

def allow_migrate_model(self, connection_alias, model):

Return whether or not a model may be migrated.

This is a thin wrapper around router.allow_migrate_model() that preemptively rejects any proxy, swapped out, or unmanaged model.

def database_backwards(self, app_label, schema_editor, from_state, to_state):
overridden in django.contrib.postgres.operations.CreateCollation, django.contrib.postgres.operations.CreateExtension, django.contrib.postgres.operations.RemoveCollation, django.contrib.postgres.operations.ValidateConstraint, django.db.migrations.operations.AddConstraint, django.db.migrations.operations.AddField, django.db.migrations.operations.AddIndex, django.db.migrations.operations.AlterField, django.db.migrations.operations.AlterModelManagers, django.db.migrations.operations.AlterModelOptions, django.db.migrations.operations.AlterModelTable, django.db.migrations.operations.AlterOrderWithRespectTo, django.db.migrations.operations.CreateModel, django.db.migrations.operations.DeleteModel, django.db.migrations.operations.RemoveConstraint, django.db.migrations.operations.RemoveField, django.db.migrations.operations.RemoveIndex, django.db.migrations.operations.RenameField, django.db.migrations.operations.RenameModel, django.db.migrations.operations.RunPython, django.db.migrations.operations.RunSQL, django.db.migrations.operations.SeparateDatabaseAndState, django.db.migrations.operations.models.AlterTogetherOptionOperation
Perform the mutation on the database schema in the reverse direction - e.g. if this were CreateModel, it would in fact drop the model's table.
def database_forwards(self, app_label, schema_editor, from_state, to_state):
overridden in django.contrib.postgres.operations.CreateCollation, django.contrib.postgres.operations.CreateExtension, django.contrib.postgres.operations.RemoveCollation, django.contrib.postgres.operations.ValidateConstraint, django.db.migrations.operations.AddConstraint, django.db.migrations.operations.AddField, django.db.migrations.operations.AddIndex, django.db.migrations.operations.AlterField, django.db.migrations.operations.AlterModelManagers, django.db.migrations.operations.AlterModelOptions, django.db.migrations.operations.AlterModelTable, django.db.migrations.operations.AlterOrderWithRespectTo, django.db.migrations.operations.CreateModel, django.db.migrations.operations.DeleteModel, django.db.migrations.operations.RemoveConstraint, django.db.migrations.operations.RemoveField, django.db.migrations.operations.RemoveIndex, django.db.migrations.operations.RenameField, django.db.migrations.operations.RenameModel, django.db.migrations.operations.RunPython, django.db.migrations.operations.RunSQL, django.db.migrations.operations.SeparateDatabaseAndState, django.db.migrations.operations.models.AlterTogetherOptionOperation
Perform the mutation on the database schema in the normal (forwards) direction.
def deconstruct(self):
overridden in django.contrib.postgres.operations.ValidateConstraint, django.db.migrations.operations.AddConstraint, django.db.migrations.operations.AddField, django.db.migrations.operations.AddIndex, django.db.migrations.operations.AlterField, django.db.migrations.operations.AlterModelManagers, django.db.migrations.operations.AlterModelOptions, django.db.migrations.operations.AlterModelTable, django.db.migrations.operations.AlterOrderWithRespectTo, django.db.migrations.operations.CreateModel, django.db.migrations.operations.DeleteModel, django.db.migrations.operations.RemoveConstraint, django.db.migrations.operations.RemoveField, django.db.migrations.operations.RemoveIndex, django.db.migrations.operations.RenameField, django.db.migrations.operations.RenameModel, django.db.migrations.operations.RunPython, django.db.migrations.operations.RunSQL, django.db.migrations.operations.SeparateDatabaseAndState, django.contrib.postgres.operations.CollationOperation, django.db.migrations.operations.models.AlterTogetherOptionOperation
Return a 3-tuple of class import path (or just name if it lives under django.db.migrations), positional arguments, and keyword arguments.
def describe(self):
overridden in django.contrib.postgres.operations.CreateCollation, django.contrib.postgres.operations.CreateExtension, django.contrib.postgres.operations.RemoveCollation, django.contrib.postgres.operations.ValidateConstraint, django.db.migrations.operations.AddConstraint, django.db.migrations.operations.AddField, django.db.migrations.operations.AddIndex, django.db.migrations.operations.AlterField, django.db.migrations.operations.AlterModelManagers, django.db.migrations.operations.AlterModelOptions, django.db.migrations.operations.AlterModelTable, django.db.migrations.operations.AlterOrderWithRespectTo, django.db.migrations.operations.CreateModel, django.db.migrations.operations.DeleteModel, django.db.migrations.operations.RemoveConstraint, django.db.migrations.operations.RemoveField, django.db.migrations.operations.RemoveIndex, django.db.migrations.operations.RenameField, django.db.migrations.operations.RenameModel, django.db.migrations.operations.RunPython, django.db.migrations.operations.RunSQL, django.db.migrations.operations.SeparateDatabaseAndState, django.db.migrations.operations.models.AlterTogetherOptionOperation
Output a brief summary of what the action does.
def reduce(self, operation, app_label):
overridden in django.db.migrations.operations.fields.FieldOperation, django.db.migrations.operations.models.ModelOperation
Return either a list of operations the actual operation should be replaced with or a boolean that indicates whether or not the specified operation can be optimized across.
def references_field(self, model_name, name, app_label):
overridden in django.db.migrations.operations.AlterOrderWithRespectTo, django.db.migrations.operations.fields.FieldOperation, django.db.migrations.operations.models.AlterTogetherOptionOperation

Return True if there is a chance this operation references the given field name, with an app label for accuracy.

Used for optimization. If in doubt, return True.

def references_model(self, name, app_label):
overridden in django.db.migrations.operations.fields.FieldOperation, django.db.migrations.operations.models.ModelOperation

Return True if there is a chance this operation references the given model name (as a string), with an app label for accuracy.

Used for optimization. If in doubt, return True; returning a false positive will merely make the optimizer a little less efficient, while returning a false negative may result in an unusable optimized migration.

def state_forwards(self, app_label, state):
overridden in django.contrib.postgres.operations.CreateExtension, django.contrib.postgres.operations.ValidateConstraint, django.db.migrations.operations.AddConstraint, django.db.migrations.operations.AddField, django.db.migrations.operations.AddIndex, django.db.migrations.operations.AlterField, django.db.migrations.operations.AlterModelManagers, django.db.migrations.operations.AlterModelOptions, django.db.migrations.operations.AlterModelTable, django.db.migrations.operations.AlterOrderWithRespectTo, django.db.migrations.operations.CreateModel, django.db.migrations.operations.DeleteModel, django.db.migrations.operations.RemoveConstraint, django.db.migrations.operations.RemoveField, django.db.migrations.operations.RemoveIndex, django.db.migrations.operations.RenameField, django.db.migrations.operations.RenameModel, django.db.migrations.operations.RunPython, django.db.migrations.operations.RunSQL, django.db.migrations.operations.SeparateDatabaseAndState, django.contrib.postgres.operations.CollationOperation, django.db.migrations.operations.models.AlterTogetherOptionOperation
Take the state from the previous migration, and mutate it so that it matches what this migration would perform.
atomic: bool =
overridden in django.db.migrations.operations.RunPython

Undocumented

elidable: bool =
overridden in django.db.migrations.operations.RunPython, django.db.migrations.operations.RunSQL

Undocumented

reduces_to_sql: bool =
overridden in django.db.migrations.operations.RunPython

Undocumented

reversible: bool =
overridden in django.contrib.postgres.operations.CreateExtension, django.db.migrations.operations.RunPython, django.db.migrations.operations.RunSQL

Undocumented

serialization_expand_args: list =
overridden in django.db.migrations.operations.AlterModelManagers, django.db.migrations.operations.CreateModel, django.db.migrations.operations.SeparateDatabaseAndState

Undocumented

_constructor_args =

Undocumented

@property
migration_name_fragment =
overridden in django.contrib.postgres.operations.CreateCollation, django.contrib.postgres.operations.CreateExtension, django.contrib.postgres.operations.RemoveCollation, django.contrib.postgres.operations.ValidateConstraint, django.db.migrations.operations.AddConstraint, django.db.migrations.operations.AddField, django.db.migrations.operations.AddIndex, django.db.migrations.operations.AlterField, django.db.migrations.operations.AlterModelManagers, django.db.migrations.operations.AlterModelOptions, django.db.migrations.operations.AlterModelTable, django.db.migrations.operations.AlterOrderWithRespectTo, django.db.migrations.operations.CreateModel, django.db.migrations.operations.DeleteModel, django.db.migrations.operations.RemoveConstraint, django.db.migrations.operations.RemoveField, django.db.migrations.operations.RemoveIndex, django.db.migrations.operations.RenameField, django.db.migrations.operations.RenameModel, django.db.migrations.operations.models.AlterTogetherOptionOperation
A filename part suitable for automatically naming a migration containing this operation, or None if not applicable.