Commit 4ccdf6e5 authored by Helen Sherwood-Taylor's avatar Helen Sherwood-Taylor Committed by Tim Graham
Browse files

Fixed #24041 -- Documented effect of changing a model instance's primary key.

parent 3daa9d60

docs/ref/models/fields.txt

+7 −2
Original line number Diff line number Diff line
@@ -278,8 +278,13 @@ don't need to set ``primary_key=True`` on any of your fields unless you want to 
override the default primary-key behavior. For more, see

:ref:`automatic-primary-key-fields`.



``primary_key=True`` implies :attr:`null=False <Field.null>` and :attr:`unique=True <Field.unique>`.

Only one primary key is allowed on an object.

``primary_key=True`` implies :attr:`null=False <Field.null>` and

:attr:`unique=True <Field.unique>`. Only one primary key is allowed on an

object.



The primary key field is read-only. If you change the value of the primary

key on an existing object and then save it, a new object will be created

alongside the old one.



``unique``

----------

docs/topics/db/models.txt

+17 −0
Original line number Diff line number Diff line
@@ -213,6 +213,23 @@ ones: 
    unless you want to override the default primary-key behavior. For more,

    see :ref:`automatic-primary-key-fields`.



    The primary key field is read-only. If you change the value of the primary

    key on an existing object and then save it, a new object will be created

    alongside the old one. For example::



        from django.db import models



        class Fruit(models.Model):

            name = models.CharField(max_length=100, primary_key=True)



    .. code-block:: pycon



        >>> fruit = Fruit.objects.create(name='Apple')

        >>> fruit.name = 'Pear'

        >>> fruit.save()

        >>> Fruit.objects.values_list('name', flat=True)

        ['Apple', 'Pear']



:attr:`~Field.unique`

    If ``True``, this field must be unique throughout the table.