Fixed #2026 -- Added support for 'and' in template 'if' tags, added dozens of unit tests and updated docs. Thanks, ckknight

git-svn-id: http://code.djangoproject.com/svn/django/trunk@3108 bcc190cf-cafb-0310-a4f2-bffc1f526a37

1 files changed, 20 insertions, 8 deletions

diff --git a/docs/templates.txt b/docs/templates.txt
index c191b409f4..69251df8bb 100644
--- a/docs/templates.txt
+++ b/docs/templates.txt
@@ -454,8 +454,12 @@ displayed by the ``{{ athlete_list|length }}`` variable.
 As you can see, the ``if`` tag can take an option ``{% else %}`` clause that
 will be displayed if the test fails.
 
-``if`` tags may use ``or`` or ``not`` to test a number of variables or to negate
-a given variable::
+``if`` tags may use ``and``, ``or`` or ``not`` to test a number of variables or
+to negate a given variable::
+
+    {% if athlete_list and coach_list %}
+        Both athletes and coaches are available.
+    {% endif %}
 
     {% if not athlete_list %}
         There are no athletes.
@@ -468,16 +472,24 @@ a given variable::
     {% if not athlete_list or coach_list %}
         There are no athletes or there are some coaches (OK, so
         writing English translations of boolean logic sounds
-        stupid; it's not my fault).
+        stupid; it's not our fault).
+    {% endif %}
+
+    {% if athlete_list and not coach_list %}
+        There are some athletes and absolutely no coaches.
     {% endif %}
 
-For simplicity, ``if`` tags do not allow ``and`` clauses; use nested ``if``
-tags instead::
+``if`` tags don't allow ``and`` and ``or`` clauses within the same tag, because
+the order of logic would be ambiguous. For example, this is invalid::
+
+    {% if athlete_list and coach_list or cheerleader_list %}
+
+If you need to combine ``and`` and ``or`` to do advanced logic, just use nested
+``if`` tags. For example::
 
     {% if athlete_list %}
-        {% if coach_list %}
-            Number of athletes: {{ athlete_list|length }}.
-            Number of coaches: {{ coach_list|length }}.
+        {% if coach_list or cheerleader_list %}
+            We have athletes, and either coaches or cheerleaders!
         {% endif %}
     {% endif %}