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Code Issues 25 Releases Wiki Activity

Fixed some stale documentation that was advising against the use of OneToOneFields. Post queryset refactor, that warning is no longer required.

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git-svn-id: http://code.djangoproject.com/svn/django/trunk@7633 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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Russell Keith-Magee 2008-06-14 14:19:28 +00:00
parent 363e46b22c
commit 42668dcc79
1 changed files with 31 additions and 6 deletions
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37
docs/db-api.txt
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@ -2037,6 +2037,37 @@ Each "reverse" operation described in this section has an immediate effect on
the database. Every addition, creation and deletion is immediately and
automatically saved to the database.
One-to-one relationships
------------------------
One-to-one relationships are very similar to Many-to-one relationships.
If you define a OneToOneField on your model, instances of that model will have
access to the related object via a simple attribute of the model.
For example::
class EntryDetail(models.Model):
entry = models.OneToOneField(Entry)
details = models.TextField()
ed = EntryDetail.objects.get(id=2)
ed.entry # Returns the related Entry object.
The difference comes in reverse queries. The related model in a One-to-one
relationship also has access to a ``Manager`` object; however, that ``Manager``
represents a single object, rather than a collection of objects::
e = Entry.objects.get(id=2)
e.entrydetail # returns the related EntryDetail object
If no object has been assigned to this relationship, Django will raise
a ``DoesNotExist`` exception.
Instances can be assigned to the reverse relationship in the same way as
you would assign the forward relationship::
e.entrydetail = ed
Many-to-many relationships
--------------------------
@ -2064,12 +2095,6 @@ above example, if the ``ManyToManyField`` in ``Entry`` had specified
``related_name='entries'``, then each ``Author`` instance would have an
``entries`` attribute instead of ``entry_set``.
One-to-one relationships
------------------------
The semantics of one-to-one relationships will be changing soon, so we don't
recommend you use them.
How are the backward relationships possible?
--------------------------------------------