Changeset 4637

Timestamp:

02/26/07 22:27:47 (2 years ago)

Author:

jacob

Message:

Fixed #2565: added a note about the laziness of querysets in tutorial 4. Thanks, Ubernostrum.

Files:

• django/trunk/docs/tutorial04.txt (modified) (1 diff)

django/trunk/docs/tutorial04.txt

@@ -207 +207 @@
-template. Note that we use ``dict()`` to return an altered dictionary in place.
-
+.. note:: ``all()`` is lazy
+
+    It might look a little frightening to see ``Poll.objects.all()`` being used
+    in a detail view which only needs one ``Poll`` object, but don't worry;
+    ``Poll.objects.all()`` is actually a special object called a ``QuerySet``,
+    which is "lazy" and doesn't hit your database until it absolutely has to. By
+    the time the database query happens, the ``object_detail`` generic view will
+    have narrowed its scope down to a single object, so the eventual query will
+    only select one row from the database. 
+    
+    If you'd like to know more about how that works, The Django database API
+    documentation `explains the lazy nature of QuerySet objects`_.
+
+.. _explains the lazy nature of QuerySet objects: ../db_api/#querysets-are-lazy
+
-In previous parts of the tutorial, the templates have been provided with a context
-that contains the ``poll`` and ``latest_poll_list`` context variables. However,