id summary reporter owner description type status component version severity resolution keywords cc stage has_patch needs_docs needs_tests needs_better_patch easy ui_ux 7251 Template if/ifequal/ifnotequal evaluate despite condition Joshua 'jag' Ginsberg nobody "The problem: Django evaluates all branches of an if/else/endif regardless of the condition. Most of the time, given the forgiving nature of templates, this is fine. However sometimes this is really bad. {{{ root@agilus:/srv/django/satchmo# ./manage.py shell Python 2.5.1 (r251:54863, Mar 7 2008, 03:19:34) [GCC 4.1.2 (Ubuntu 4.1.2-0ubuntu4)] on linux2 Type ""help"", ""copyright"", ""credits"" or ""license"" for more information. (InteractiveConsole) >>> from satchmo.shop.templatetags import satchmo_util >>> satchmo_util.app_enabled(""recentlist"") '' >>> from django.template import Template, RequestContext >>> t = Template(""""""{% load satchmo_util %}{% if ""recentlist""|app_enabled %}Enabled{% endif %}"""""") >>> from django.template import Context >>> ctx = Context({}) >>> t.render(ctx) u'' >>> t = Template(""""""{% load satchmo_util %}{% if ""recentlist""|app_enabled %}{% load satchmo_recentlist %}{% endif %}"""""") Traceback (most recent call last): File """", line 1, in File ""/usr/local/lib/python2.5/site-packages/django/template/__init__.py"", line 166, in __init__ self.nodelist = compile_string(template_string, origin) File ""/usr/local/lib/python2.5/site-packages/django/template/__init__.py"", line 187, in compile_string return parser.parse() File ""/usr/local/lib/python2.5/site-packages/django/template/__init__.py"", line 271, in parse compiled_result = compile_func(self, token) File ""/usr/local/lib/python2.5/site-packages/django/template/defaulttags.py"", line 764, in do_if nodelist_true = parser.parse(('else', 'endif')) File ""/usr/local/lib/python2.5/site-packages/django/template/__init__.py"", line 271, in parse compiled_result = compile_func(self, token) File ""/usr/local/lib/python2.5/site-packages/django/template/defaulttags.py"", line 857, in load (taglib, e)) TemplateSyntaxError: 'satchmo_recentlist' is not a valid tag library: Could not load template library from django.templatetags.satchmo_recentlist, No module named satchmo_recentlist }}} Django shouldn't have even evaluated the {% load satchmo_recentlist %} because the condition clearly fails. The same bug exists for ifequals and ifnotequals. With the attached patch applied, we see the following behavior, which I believe is correct: {{{ root@agilus:/srv/django/satchmo# ./manage.py shell Python 2.5.1 (r251:54863, Mar 7 2008, 03:19:34) [GCC 4.1.2 (Ubuntu 4.1.2-0ubuntu4)] on linux2 Type ""help"", ""copyright"", ""credits"" or ""license"" for more information. (InteractiveConsole) >>> from satchmo.shop.templatetags import satchmo_util >>> satchmo_util.app_enabled(""recentlist"") '' >>> from django.template import Template, Context >>> t = Template(""""""{% load satchmo_util %}{% if ""recentlist""|app_enabled %}Enabled{% endif %}"""""") >>> ctx = Context({}) >>> t.render(ctx) u'' >>> t = Template(""""""{% load satchmo_util %}{% if ""recentlist""|app_enabled %}{% load satchmo_recentlist %}{% endif %}"""""") >>> t.render(ctx) u'' >>> t = Template(""""""{% load satchmo_util %}{% if ""recentlist""|app_enabled %}{% load satchmo_recentlist %}{% else %}{% load nonexistant_tags %}{% endif %}"""""") >>> t.render(ctx) Traceback (most recent call last): File """", line 1, in File ""/usr/local/lib/python2.5/site-packages/django/template/__init__.py"", line 176, in render return self.nodelist.render(context) File ""/usr/local/lib/python2.5/site-packages/django/template/__init__.py"", line 751, in render bits.append(self.render_node(node, context)) File ""/usr/local/lib/python2.5/site-packages/django/template/debug.py"", line 71, in render_node result = node.render(context) File ""/usr/local/lib/python2.5/site-packages/django/template/defaulttags.py"", line 251, in render raise self.nodelist_false TemplateSyntaxError: 'nonexistant_tags' is not a valid tag library: Could not load template library from django.templatetags.nonexistant_tags, No module named nonexistant_tags >>> t = Template(""""""{% load satchmo_util %}{% if not ""recentlist""|app_enabled %}{% load satchmo_recentlist %}{% endif %}"""""") >>> t.render(ctx) Traceback (most recent call last): File """", line 1, in File ""/usr/local/lib/python2.5/site-packages/django/template/__init__.py"", line 176, in render return self.nodelist.render(context) File ""/usr/local/lib/python2.5/site-packages/django/template/__init__.py"", line 751, in render bits.append(self.render_node(node, context)) File ""/usr/local/lib/python2.5/site-packages/django/template/debug.py"", line 71, in render_node result = node.render(context) File ""/usr/local/lib/python2.5/site-packages/django/template/defaulttags.py"", line 246, in render raise self.nodelist_true TemplateSyntaxError: 'satchmo_recentlist' is not a valid tag library: Could not load template library from django.templatetags.satchmo_recentlist, No module named satchmo_recentlist >>> t = Template(""""""{% load satchmo_util %}{% if ""recentlist""|app_enabled %}{% load satchmo_recentlist %}{% else %}Disabled{% endif %}"""""") >>> t.render(ctx) u'Disabled' >>> t = Template(""""""{% load satchmo_util %}{% ifequal 3 4 %}{% load satchmo_recentlist %}{% else %}Disabled{% endifequal %}"""""") >>> t.render(ctx) }}} Thanks! -jag" closed Template system dev wontfix Accepted 1 0 0 0 0 0