diff options
Diffstat (limited to 'docs/ref/models')
| -rw-r--r-- | docs/ref/models/fields.txt | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/docs/ref/models/fields.txt b/docs/ref/models/fields.txt index d1fc04d3b5..9fd9bd7fa3 100644 --- a/docs/ref/models/fields.txt +++ b/docs/ref/models/fields.txt @@ -1291,6 +1291,30 @@ The possible values for :attr:`~ForeignKey.on_delete` are found in If in doubt, leave it to its default of ``True``. +.. attribute:: ForeignKey.allow_unsaved_instance_assignment + + .. versionadded:: 1.8 + + This flag was added for backwards compatibility as older versions of + Django always allowed assigning unsaved model instances. + + Django prevents unsaved model instances from being assigned to a + ``ForeignKey`` field to prevent accidental data loss (unsaved foreign keys + are silently ignored when saving a model instance). + + If you require allowing the assignment of unsaved instances and aren't + concerned about the data loss possibility (e.g. you never save the objects + to the database), you can disable this check by creating a subclass of the + field class and setting its ``allow_unsaved_instance_assignment`` attribute + to ``True``. For example:: + + class UnsavedForeignKey(models.ForeignKey): + # A ForeignKey which can point to an unsaved object + allow_unsaved_instance_assignment = True + + class Book(models.Model): + author = UnsavedForeignKey(Author) + .. _ref-manytomany: ``ManyToManyField`` @@ -1388,7 +1412,7 @@ that control how the relationship functions. * ``<other_model>_id``: the ``id`` of the model that the ``ManyToManyField`` points to. - If the ``ManyToManyField`` points from and to the same model, the following + If the ``ManyToManyField`` points from and to the same model, the following fields are generated: * ``id``: the primary key of the relation. @@ -1483,6 +1507,12 @@ that control how the relationship functions. If in doubt, leave it to its default of ``True``. +.. attribute:: ManyToManyField.allow_unsaved_instance_assignment + + .. versionadded:: 1.8 + + Works analogously to :attr:`ForeignKey.allow_unsaved_instance_assignment`. + :class:`ManyToManyField` does not support :attr:`~Field.validators`. :attr:`~Field.null` has no effect since there is no way to require a |