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Fixed #4303 -- Fixed typos in docs/db-api.txt. Thanks, Gary Wilson
git-svn-id: http://code.djangoproject.com/svn/django/trunk@5253 bcc190cf-cafb-0310-a4f2-bffc1f526a37
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@ -143,8 +143,8 @@ or ``UPDATE`` SQL statements. Specifically, when you call ``save()``, Django
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follows this algorithm:
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* If the object's primary key attribute is set to a value that evaluates to
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``True`` (i.e., a value other than ``None`` or the empty string), Django
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executes a ``SELECT`` query to determine whether a record with the given
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``True`` (i.e., a value other than ``None`` or the empty string), Django
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executes a ``SELECT`` query to determine whether a record with the given
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primary key already exists.
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* If the record with the given primary key does already exist, Django
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executes an ``UPDATE`` query.
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@ -525,19 +525,19 @@ Examples::
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[datetime.datetime(2005, 3, 20), datetime.datetime(2005, 2, 20)]
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>>> Entry.objects.filter(headline__contains='Lennon').dates('pub_date', 'day')
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[datetime.datetime(2005, 3, 20)]
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``none()``
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~~~~~~~~~~
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**New in Django development version**
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Returns an ``EmptyQuerySet`` -- a ``QuerySet`` that always evaluates to
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Returns an ``EmptyQuerySet`` -- a ``QuerySet`` that always evaluates to
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an empty list. This can be used in cases where you know that you should
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return an empty result set and your caller is expecting a ``QuerySet``
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object (instead of returning an empty list, for example.)
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Examples::
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>>> Entry.objects.none()
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[]
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@ -610,7 +610,7 @@ follow::
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c = p.hometown # Requires a database call.
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The ``depth`` argument is new in the Django development version.
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``extra(select=None, where=None, params=None, tables=None)``
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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@ -1136,7 +1136,7 @@ such as January 3, July 3, etc.
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isnull
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~~~~~~
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Takes either ``True`` or ``False``, which correspond to SQL queries of
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Takes either ``True`` or ``False``, which correspond to SQL queries of
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``IS NULL`` and ``IS NOT NULL``, respectively.
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Example::
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@ -1149,10 +1149,10 @@ SQL equivalent::
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.. admonition:: ``__isnull=True`` vs ``__exact=None``
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There is an important difference between ``__isnull=True`` and
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There is an important difference between ``__isnull=True`` and
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``__exact=None``. ``__exact=None`` will *always* return an empty result
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set, because SQL requires that no value is equal to ``NULL``.
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``__isnull`` determines if the field is currently holding the value
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set, because SQL requires that no value is equal to ``NULL``.
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``__isnull`` determines if the field is currently holding the value
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of ``NULL`` without performing a comparison.
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search
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@ -1181,7 +1181,7 @@ The pk lookup shortcut
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----------------------
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For convenience, Django provides a ``pk`` lookup type, which stands for
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"primary_key".
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"primary_key".
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In the example ``Blog`` model, the primary key is the ``id`` field, so these
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three statements are equivalent::
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@ -1190,14 +1190,14 @@ three statements are equivalent::
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Blog.objects.get(id=14) # __exact is implied
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Blog.objects.get(pk=14) # pk implies id__exact
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The use of ``pk`` isn't limited to ``__exact`` queries -- any query term
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The use of ``pk`` isn't limited to ``__exact`` queries -- any query term
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can be combined with ``pk`` to perform a query on the primary key of a model::
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# Get blogs entries with id 1, 4 and 7
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Blog.objects.filter(pk__in=[1,4,7])
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# Get all blog entries with id > 14
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Blog.objects.filter(pk__gt=14)
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Blog.objects.filter(pk__gt=14)
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``pk`` lookups also work across joins. For example, these three statements are
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equivalent::
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@ -1754,19 +1754,19 @@ get_object_or_404()
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-------------------
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One common idiom to use ``get()`` and raise ``Http404`` if the
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object doesn't exist. This idiom is captured by ``get_object_or_404()``.
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This function takes a Django model as its first argument and an
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arbitrary number of keyword arguments, which it passes to the manager's
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object doesn't exist. This idiom is captured by ``get_object_or_404()``.
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This function takes a Django model as its first argument and an
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arbitrary number of keyword arguments, which it passes to the manager's
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``get()`` function. It raises ``Http404`` if the object doesn't
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exist. For example::
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exist. For example::
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# Get the Entry with a primary key of 3
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e = get_object_or_404(Entry, pk=3)
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When you provide a model to this shortcut function, the default manager
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is used to execute the underlying ``get()`` query. If you don't want to
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use the default manager, or you want to search a list of related objects,
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you can provide ``get_object_or_404()`` with a manager object, instead.
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When you provide a model to this shortcut function, the default manager
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is used to execute the underlying ``get()`` query. If you don't want to
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use the default manager, or if you want to search a list of related objects,
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you can provide ``get_object_or_404()`` with a manager object instead.
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For example::
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# Get the author of blog instance `e` with a name of 'Fred'
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@ -1779,8 +1779,8 @@ For example::
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get_list_or_404()
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-----------------
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``get_list_or_404`` behaves the same was as ``get_object_or_404()``
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-- except that it uses using ``filter()`` instead of ``get()``. It raises
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``get_list_or_404`` behaves the same way as ``get_object_or_404()``
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-- except that it uses ``filter()`` instead of ``get()``. It raises
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``Http404`` if the list is empty.
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Falling back to raw SQL
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