Add "myifchanged" tag, which is different from the standard ifchanged

in two ways:
 * It permits an "else" clause.  This code is from http://code.djangoproject.com/ticket/4534
 * It doesn't push the context while rendering, so context changes can be performed (like the change that cycle makes: putting the current value into the context)

Use this new tag to cycle the row color if the ballot_id has changed, or
if it's a synthetic document.
 - Legacy-Id: 380

Author: fenner

ietf/idtracker/templatetags/myifchanged.py

@@ -0,0 +1,85 @@
+"""A copy of the IfChanged standard node, updated with
+SmileyChris's patch in http://code.djangoproject.com/ticket/4534
+and with the context push removed."""
+
+
+from django.template import Node, NodeList, resolve_variable
+from django.template import VariableDoesNotExist
+from django.template import Library
+from django.conf import settings
+import sys
+
+register = Library()
+
+class MyIfChangedNode(Node):
+    def __init__(self, nodelist_true, nodelist_false, *varlist):
+        self.nodelist_true, self.nodelist_false = nodelist_true, nodelist_false
+        self._last_seen = None
+        self._varlist = varlist
+
+    def render(self, context):
+        if context.has_key('forloop') and context['forloop']['first']:
+            self._last_seen = None
+        try:
+            if self._varlist:
+                # Consider multiple parameters.
+                # This automatically behaves like a OR evaluation of the multiple variables.
+                compare_to = [resolve_variable(var, context) for var in self._varlist]
+            else:
+                compare_to = self.nodelist_true.render(context)
+        except VariableDoesNotExist:
+            compare_to = None        
+
+        if  compare_to != self._last_seen:
+            firstloop = (self._last_seen == None)
+            self._last_seen = compare_to
+            #context.push()
+            #context['ifchanged'] = {'firstloop': firstloop}
+            content = self.nodelist_true.render(context)
+            #context.pop()
+            return content
+        else:
+            if self.nodelist_false:
+                return self.nodelist_false.render(context)
+            else:
+                return ''
+
+#@register.tag
+def myifchanged(parser, token):
+    """
+    Check if a value has changed from the last iteration of a loop.
+
+    The 'myifchanged' block tag is used within a loop. It has two possible uses.
+
+    1. Checks its own rendered contents against its previous state and only
+       displays the content if it has changed. For example, this displays a list of
+       days, only displaying the month if it changes::
+
+            <h1>Archive for {{ year }}</h1>
+
+            {% for date in days %}
+                {% myifchanged %}<h3>{{ date|date:"F" }}</h3>{% endmyifchanged %}
+                <a href="{{ date|date:"M/d"|lower }}/">{{ date|date:"j" }}</a>
+            {% endfor %}
+
+    2. If given a variable, check whether that variable has changed. For example, the
+       following shows the date every time it changes, but only shows the hour if both
+       the hour and the date have changed::
+
+            {% for date in days %}
+                {% myifchanged date.date %} {{ date.date }} {% endmyifchanged %}
+                {% myifchanged date.hour date.date %}
+                    {{ date.hour }}
+                {% endmyifchanged %}
+            {% endfor %}
+    """
+    bits = token.contents.split()
+    nodelist_true = parser.parse(('else', 'endmyifchanged'))
+    token = parser.next_token()
+    if token.contents == 'else':
+        nodelist_false = parser.parse(('endmyifchanged',))
+        parser.delete_first_token()
+    else:
+        nodelist_false = NodeList()
+    return MyIfChangedNode(nodelist_true, nodelist_false, *bits[1:])
+myifchanged = register.tag(myifchanged)

ietf/templates/idtracker/search_result_row.html

@@ -1,4 +1,5 @@
-	<tr bgcolor="#{% if match.primary_flag %}{% cycle F8D6F8,E2AFE2 as ballotcolor %}{% else %}{{ ballotcolor }}{% endif %}">
+{% load myifchanged %}
+	<tr bgcolor="#{% myifchanged match.ballot_id %}{% cycle F8D6F8,E2AFE2 as ballotcolor %}{% else %}{% if match.synthetic %}{% cycle ballotcolor %}{% else %}{{ ballotcolor }}{% endif %}{% endmyifchanged %}">
 	{% if match.synthetic %}
 	<td>&nbsp;</td>
 	{% else %}
@@ -30,7 +31,7 @@
 	    {% endif %}
         </td>
 	<td>{{ match.document.revision }}</td>
-	<td>{% firstof match.job_owner "Not Assigned Yet" %}</td>
+	<td>{{ match.job_owner }}</td>
 	<td>{% firstof match.status_date "" %}</td>
 	<td>{{ match.event_date }}</td>
 	</tr>