Slight fixes to related fields reference to avoid conflicting target names
with the queryset docs. git-svn-id: http://code.djangoproject.com/svn/django/trunk@13272 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Jacob Kaplan-Moss
parent
acd8dcd5b0
commit
47e3cc74d9
|
|
@ -6,93 +6,100 @@ Related objects reference
|
|||
|
||||
.. currentmodule:: django.db.models.fields.related
|
||||
|
||||
This document describes extra methods available on managers when used in a one-to-many or many-to-many related context. This happens in two cases:
|
||||
.. class:: RelatedManager
|
||||
|
||||
* The "other side" of a ``ForeignKey`` relation. That is::
|
||||
A "related manager" is a on managers used in a one-to-many or many-to-many
|
||||
related context. This happens in two cases:
|
||||
|
||||
class Reporter(models.Model):
|
||||
...
|
||||
* The "other side" of a ``ForeignKey`` relation. That is::
|
||||
|
||||
class Article(models.Model):
|
||||
reporter = models.ForeignKey(Reporter)
|
||||
class Reporter(models.Model):
|
||||
...
|
||||
|
||||
In the above example, the methods below will be available on
|
||||
the manager ``reporter.article_set``.
|
||||
class Article(models.Model):
|
||||
reporter = models.ForeignKey(Reporter)
|
||||
|
||||
* Both sides of a ``ManyToManyField`` relation::
|
||||
In the above example, the methods below will be available on
|
||||
the manager ``reporter.article_set``.
|
||||
|
||||
class Topping(models.Model):
|
||||
...
|
||||
* Both sides of a ``ManyToManyField`` relation::
|
||||
|
||||
class Pizza(models.Model):
|
||||
toppings = models.ManyToManyField(Topping)
|
||||
class Topping(models.Model):
|
||||
...
|
||||
|
||||
In this example, the methods below will be available both on
|
||||
``topping.pizza_set`` and on ``pizza.toppings``.
|
||||
class Pizza(models.Model):
|
||||
toppings = models.ManyToManyField(Topping)
|
||||
|
||||
.. method:: add(obj1, [obj2, ...])
|
||||
In this example, the methods below will be available both on
|
||||
``topping.pizza_set`` and on ``pizza.toppings``.
|
||||
|
||||
Adds the specified model objects to the related object set.
|
||||
These related managers have some extra methods:
|
||||
|
||||
Example::
|
||||
.. method:: add(obj1, [obj2, ...])
|
||||
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> e = Entry.objects.get(id=234)
|
||||
>>> b.entry_set.add(e) # Associates Entry e with Blog b.
|
||||
Adds the specified model objects to the related object set.
|
||||
|
||||
.. method:: create(**kwargs)
|
||||
Example::
|
||||
|
||||
Creates a new object, saves it and puts it in the related object set.
|
||||
Returns the newly created object::
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> e = Entry.objects.get(id=234)
|
||||
>>> b.entry_set.add(e) # Associates Entry e with Blog b.
|
||||
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> e = b.entry_set.create(
|
||||
... headline='Hello',
|
||||
... body_text='Hi',
|
||||
... pub_date=datetime.date(2005, 1, 1)
|
||||
... )
|
||||
.. method:: create(**kwargs)
|
||||
|
||||
# No need to call e.save() at this point -- it's already been saved.
|
||||
Creates a new object, saves it and puts it in the related object set.
|
||||
Returns the newly created object::
|
||||
|
||||
This is equivalent to (but much simpler than)::
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> e = b.entry_set.create(
|
||||
... headline='Hello',
|
||||
... body_text='Hi',
|
||||
... pub_date=datetime.date(2005, 1, 1)
|
||||
... )
|
||||
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> e = Entry(
|
||||
.... blog=b,
|
||||
.... headline='Hello',
|
||||
.... body_text='Hi',
|
||||
.... pub_date=datetime.date(2005, 1, 1)
|
||||
.... )
|
||||
>>> e.save(force_insert=True)
|
||||
# No need to call e.save() at this point -- it's already been saved.
|
||||
|
||||
Note that there's no need to specify the keyword argument of the model that
|
||||
defines the relationship. In the above example, we don't pass the parameter
|
||||
``blog`` to ``create()``. Django figures out that the new ``Entry`` object's
|
||||
``blog`` field should be set to ``b``.
|
||||
This is equivalent to (but much simpler than)::
|
||||
|
||||
.. method:: remove(obj1, [obj2, ...])
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> e = Entry(
|
||||
.... blog=b,
|
||||
.... headline='Hello',
|
||||
.... body_text='Hi',
|
||||
.... pub_date=datetime.date(2005, 1, 1)
|
||||
.... )
|
||||
>>> e.save(force_insert=True)
|
||||
|
||||
Removes the specified model objects from the related object set::
|
||||
Note that there's no need to specify the keyword argument of the model
|
||||
that defines the relationship. In the above example, we don't pass the
|
||||
parameter ``blog`` to ``create()``. Django figures out that the new
|
||||
``Entry`` object's ``blog`` field should be set to ``b``.
|
||||
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> e = Entry.objects.get(id=234)
|
||||
>>> b.entry_set.remove(e) # Disassociates Entry e from Blog b.
|
||||
.. method:: remove(obj1, [obj2, ...])
|
||||
|
||||
In order to prevent database inconsistency, this method only exists on
|
||||
``ForeignKey`` objects where ``null=True``. If the related field can't be
|
||||
set to ``None`` (``NULL``), then an object can't be removed from a relation
|
||||
without being added to another. In the above example, removing ``e`` from
|
||||
``b.entry_set()`` is equivalent to doing ``e.blog = None``, and because the
|
||||
``blog`` ``ForeignKey`` doesn't have ``null=True``, this is invalid.
|
||||
Removes the specified model objects from the related object set::
|
||||
|
||||
.. method:: clear()
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> e = Entry.objects.get(id=234)
|
||||
>>> b.entry_set.remove(e) # Disassociates Entry e from Blog b.
|
||||
|
||||
Removes all objects from the related object set::
|
||||
In order to prevent database inconsistency, this method only exists on
|
||||
``ForeignKey`` objects where ``null=True``. If the related field can't
|
||||
be set to ``None`` (``NULL``), then an object can't be removed from a
|
||||
relation without being added to another. In the above example, removing
|
||||
``e`` from ``b.entry_set()`` is equivalent to doing ``e.blog = None``,
|
||||
and because the ``blog`` ``ForeignKey`` doesn't have ``null=True``, this
|
||||
is invalid.
|
||||
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> b.entry_set.clear()
|
||||
.. method:: clear()
|
||||
|
||||
Note this doesn't delete the related objects -- it just disassociates them.
|
||||
Removes all objects from the related object set::
|
||||
|
||||
Just like ``remove()``, ``clear()`` is only available on ``ForeignKey``\s
|
||||
where ``null=True``.
|
||||
>>> b = Blog.objects.get(id=1)
|
||||
>>> b.entry_set.clear()
|
||||
|
||||
Note this doesn't delete the related objects -- it just disassociates
|
||||
them.
|
||||
|
||||
Just like ``remove()``, ``clear()`` is only available on
|
||||
``ForeignKey``\s where ``null=True``.
|
||||
|
|
|
|||
Loading…
Reference in New Issue