Ticket #2800: ifchanged-multi-parameters.patch

django/template/defaulttags.py

@@ -124 +124 @@
         return nodelist.render(context)
 
 class IfChangedNode(Node):
-    def __init__(self, nodelist):
+    def __init__(self, nodelist, var1=None):
         self.nodelist = nodelist
         self._last_seen = None
+        self._var1 = var1
 
     def render(self, context):
         if context.has_key('forloop') and context['forloop']['first']:
             self._last_seen = None
-        content = self.nodelist.render(context)
-        if content != self._last_seen:
+        try:
+            if self._var1==None:
+                compare_to = self.nodelist.render(context)
+            else:
+                # Consider multiple parameters.
+                # This automatically behaves like a OR evaluation of the multiple variables.
+                compare_to = ",".join([str(resolve_variable(var, context)) for var in self._var1.split(",")])
+        except VariableDoesNotExist:
+            compare_to = None        
+        if  compare_to != self._last_seen:
             firstloop = (self._last_seen == None)
-            self._last_seen = content
+            self._last_seen = compare_to
             context.push()
             context['ifchanged'] = {'firstloop': firstloop}
             content = self.nodelist.render(context)
@@ -632 +641 @@
     """
     Check if a value has changed from the last iteration of a loop.
 
-    The 'ifchanged' block tag is used within a loop. It checks its own rendered
-    contents against its previous state and only displays its content if the
-    value has changed::
+    The 'ifchanged' block tag is used within a loop. It has two possible uses.
+    1) It checks its own rendered contents against its previous state and 
+    only displays its content if the value has changed.
+    2) It checks if (any of) the given variable(s) has changed. ::
 
         <h1>Archive for {{ year }}</h1>
 
         {% for date in days %}
-        {% ifchanged %}<h3>{{ date|date:"F" }}</h3>{% endifchanged %}
-        <a href="{{ date|date:"M/d"|lower }}/">{{ date|date:"j" }}</a>
+            {% ifchanged %}<h3>{{ date|date:"F" }}</h3>{% endifchanged %}
+
+            {% ifchanged date %}date has changed{% endifchanged %}
+            <a href="{{ date|date:"M/d"|lower }}/">{{ date|date:"j" }}</a>
         {% endfor %}
+        
+        <!-- 
+          This shall result in printing the date, when it changed and the hour
+          but when it changed only. The second ifchanged needs to check two variables
+          the date and the hour in case the current hour to print is the same as
+          the one from the last day. Here the special case of checking multiple
+          variables using an ifchnaged is required.
+        -->
+        {% for date in days %}
+            {% ifchanged %} {{date.date}} {% endifchanged %}
+            {% ifchanged date.hour,date.date %}
+                {{date.hour}}
+            {% endifchanged %}
+        {% endfor %}
     """
     bits = token.contents.split()
-    if len(bits) != 1:
-        raise TemplateSyntaxError, "'ifchanged' tag takes no arguments"
+    if len(bits) > 2:
+        raise TemplateSyntaxError, "'ifchanged' tag takes either one or none argument"
+    if len(bits) == 1:
+        bits.append(None)
     nodelist = parser.parse(('endifchanged',))
     parser.delete_first_token()
-    return IfChangedNode(nodelist)
+    return IfChangedNode(nodelist, bits[1])
 ifchanged = register.tag(ifchanged)
 
 #@register.tag

tests/regressiontests/templates/tests.py

@@ -309 +309 @@
             'ifchanged05': ('{% for n in num %}{% ifchanged %}{{ n }}{% endifchanged %}{% for x in numx %}{% ifchanged %}{{ x }}{% endifchanged %}{% endfor %}{% endfor %}', { 'num': (1, 1, 1), 'numx': (1, 2, 3)}, '1123123123'),
             'ifchanged06': ('{% for n in num %}{% ifchanged %}{{ n }}{% endifchanged %}{% for x in numx %}{% ifchanged %}{{ x }}{% endifchanged %}{% endfor %}{% endfor %}', { 'num': (1, 1, 1), 'numx': (2, 2, 2)}, '1222'),
             'ifchanged07': ('{% for n in num %}{% ifchanged %}{{ n }}{% endifchanged %}{% for x in numx %}{% ifchanged %}{{ x }}{% endifchanged %}{% for y in numy %}{% ifchanged %}{{ y }}{% endifchanged %}{% endfor %}{% endfor %}{% endfor %}', { 'num': (1, 1, 1), 'numx': (2, 2, 2), 'numy': (3, 3, 3)}, '1233323332333'),
+            # Test one parameter given to ifchanged.
+            'ifchanged-param01': ('{% for n in num %}{% ifchanged n %}..{% endifchanged %}{{n}}{% endfor %}', { 'num': (1,2,3) }, '..1..2..3'),
+            'ifchanged-param02': ('{% for n in num %}{% for x in numx %}{% ifchanged n %}..{% endifchanged %}{{x}}{% endfor %}{% endfor %}', { 'num': (1,2,3), 'numx': (5,6,7) }, '..567..567..567'),
+            # Test multiple parameters to ifchanged.
+            'ifchanged-param03': ('{% for n in num %}{{n}}{% for x in numx %}{% ifchanged x,n %}{{x}}{% endifchanged %}{% endfor %}{% endfor %}', { 'num': (1,1,2), 'numx': (5,6,6) }, '156156256'),
+            # Test a date+hour like construct, where the hour of the last day is the same but the date had changed, so print the hour anyway.
+            'ifchanged-param04': ('{% for d in days %}{%ifchanged%}{{d.day}}{%endifchanged%}{% for h in d.hours %}{% ifchanged d,h %}{{h}}{% endifchanged %}{% endfor %}{% endfor %}', {'days':[{'day':1, 'hours':[1,2,3]},{'day':2, 'hours':[3]},] }, '112323'),
+            # Logically the same as above, just written with explicit ifchanged for the day.
+            'ifchanged-param04': ('{% for d in days %}{%ifchanged d.day%}{{d.day}}{%endifchanged%}{% for h in d.hours %}{% ifchanged d.day,h %}{{h}}{% endifchanged %}{% endfor %}{% endfor %}', {'days':[{'day':1, 'hours':[1,2,3]},{'day':2, 'hours':[3]},] }, '112323'),
 
             ### IFEQUAL TAG ###########################################################
             'ifequal01': ("{% ifequal a b %}yes{% endifequal %}", {"a": 1, "b": 2}, ""),