Refs -- Added Model._state.adding to docs about copying model instances.
@@ -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()
