1
0
mirror of https://github.com/django/django.git synced 2024-12-23 01:25:58 +00:00

Refs #4027 -- Added Model._state.adding to docs about copying model instances.

This commit is contained in:
Johannes Wilm 2021-02-19 19:53:43 +01:00 committed by Mariusz Felisiak
parent 8f02a78695
commit 0fd05df7b5

View File

@ -1233,12 +1233,15 @@ Copying model instances
Although there is no built-in method for copying model instances, it is
possible to easily create new instance with all fields' values copied. In the
simplest case, you can set ``pk`` to ``None``. Using our blog example::
simplest case, you can set ``pk`` to ``None`` and
:attr:`_state.adding <django.db.models.Model._state>` to ``True``. Using our
blog example::
blog = Blog(name='My blog', tagline='Blogging is easy')
blog.save() # blog.pk == 1
blog.pk = None
blog._state.adding = True
blog.save() # blog.pk == 2
Things get more complicated if you use inheritance. Consider a subclass of
@ -1251,10 +1254,11 @@ Things get more complicated if you use inheritance. Consider a subclass of
django_blog.save() # django_blog.pk == 3
Due to how inheritance works, you have to set both ``pk`` and ``id`` to
``None``::
``None``, and ``_state.adding`` to ``True``::
django_blog.pk = None
django_blog.id = None
django_blog._state.adding = True
django_blog.save() # django_blog.pk == 4
This process doesn't copy relations that aren't part of the model's database
@ -1265,6 +1269,7 @@ entry::
entry = Entry.objects.all()[0] # some previous entry
old_authors = entry.authors.all()
entry.pk = None
entry._state.adding = True
entry.save()
entry.authors.set(old_authors)
@ -1274,6 +1279,7 @@ For example, assuming ``entry`` is already duplicated as above::
detail = EntryDetail.objects.all()[0]
detail.pk = None
detail._state.adding = True
detail.entry = entry
detail.save()