diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/topics/db/queries.txt | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/docs/topics/db/queries.txt b/docs/topics/db/queries.txt index cc77a495a0..03d18214e5 100644 --- a/docs/topics/db/queries.txt +++ b/docs/topics/db/queries.txt @@ -1237,12 +1237,15 @@ 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 @@ -1255,10 +1258,11 @@ 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 @@ -1269,6 +1273,7 @@ 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) @@ -1278,6 +1283,7 @@ 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() |