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Fixed #2800: the ifchanged tag now can optionally take paramaters to be checked for changing (instead of always using the content). Thanks, Wolfram Kriesing. 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@4050 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Jacob Kaplan-Moss 2006-11-07 05:36:51 +00:00
parent a14dba5eed
commit b1b4e8e7c4
3 changed files with 72 additions and 23 deletions
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51
django/template/defaulttags.py
View File

@ -124,17 +124,27 @@ class ForNode(Node):
return nodelist.render(context)
class IfChangedNode(Node):
def __init__(self, nodelist):
def __init__(self, nodelist, *varlist):
self.nodelist = nodelist
self._last_seen = None
self._varlist = varlist
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._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.render(context)
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)
@ -634,23 +644,34 @@ def ifchanged(parser, token):
"""
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.
<h1>Archive for {{ year }}</h1>
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::
{% for date in days %}
{% ifchanged %}<h3>{{ date|date:"F" }}</h3>{% endifchanged %}
<a href="{{ date|date:"M/d"|lower }}/">{{ date|date:"j" }}</a>
{% endfor %}
<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>
{% endfor %}
2. If given a variable, check if 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 has changed::
{% for date in days %}
{% ifchanged date.date %} {{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"
nodelist = parser.parse(('endifchanged',))
parser.delete_first_token()
return IfChangedNode(nodelist)
return IfChangedNode(nodelist, *bits[1:])
ifchanged = register.tag(ifchanged)
#@register.tag

29
docs/templates.txt
View File

@ -525,16 +525,29 @@ ifchanged
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.
<h1>Archive for {{ year }}</h1>
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::
{% for day in days %}
{% ifchanged %}<h3>{{ day|date:"F" }}</h3>{% endifchanged %}
<a href="{{ day|date:"M/d"|lower }}/">{{ day|date:"j" }}</a>
{% endfor %}
<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>
{% endfor %}
2. If given a variable, check if 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 has changed::
{% for date in days %}
{% ifchanged date.date %} {{date.date}} {% endifchanged %}
{% ifchanged date.hour date.date %}
{{date.hour}}
{% endifchanged %}
{% endfor %}
ifequal
~~~~~~~

15
tests/regressiontests/templates/tests.py
View File

@ -328,6 +328,21 @@ class Templates(unittest.TestCase):
'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}, ""),