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 23441 Maximum recursion depth exceeded when using custom `inclusion_tag` with recursion in templates and `django.template.loaders.cached.Loader` Venelin Stoykov nobody "When custom `inclusion_tag` is created which use recursion in the template (call itself) and also template loader used is `django.template.loaders.cached.Loader`. In this situation when template containing this inclusion tag is rendered for the second time (then the template is fetched from the cache) then `maximum recursion depth exceeded` error is raised. The reason for this is when `{% extends %}` template tag start to look for `{% block %}` tags it calls `Node.get_nodes_by_type` which start looking for `{% block %}` tags in the template. When reach our custom inclusion tag node and call it's `get_nodes_by_type` method to look for `{% block %}` then start iteration over cached nodes from included template. This will not happen when standard template loaders are used because template for inclusion tag is not parsed yet. To reproduce the error you can use github repo created for that purpose (https://github.com/vstoykov/wpadmin-test) I think that there is two possible approaches to fix this, both of which prevent iteration over cached nodes. 1. Set `child_nodelists` attribute of `InclusionNode` to be empty iterable (tuple for example). 2. Change the name of the attribute in which the cached nodes are stored from `nodelist` to something else. For me the first variant is preferred because we explicitly tell that this node doesn't have any child nodes. I created a patch with first variant and also a pull request. Attached Traceback: {{{ Environment: Request Method: GET Request URL: http://localhost:8000/admin/ Django Version: 1.7 Python Version: 2.7.6 Installed Applications: ('wpadmin', 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.messages', 'django.contrib.staticfiles', 'django.contrib.redirects', 'django.contrib.sites') Installed Middleware: ('django.contrib.sessions.middleware.SessionMiddleware', 'django.middleware.common.CommonMiddleware', 'django.middleware.csrf.CsrfViewMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware', 'django.contrib.auth.middleware.SessionAuthenticationMiddleware', 'django.contrib.messages.middleware.MessageMiddleware', 'django.middleware.clickjacking.XFrameOptionsMiddleware') Template error: In template /home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/wpadmin/templates/admin/base_site.html, error at line 1 maximum recursion depth exceeded 1 : {% extends ""admin/base.html"" %} 2 : {% load i18n wpadmin_tags %} 3 : 4 : {% block title %}{{ title }} | {% wpadmin_render_custom_title %}{% endblock %} 5 : 6 : {% block branding %} 7 :

{% trans 'Django administration' %}

8 : {% endblock %} 9 : 10 : {% block nav-global %}{% endblock %} 11 : Traceback: File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/core/handlers/base.py"" in get_response 137. response = response.render() File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/response.py"" in render 103. self.content = self.rendered_content File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/response.py"" in rendered_content 80. content = template.render(context) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in render 148. return self._render(context) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in _render 142. return self.nodelist.render(context) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in render 844. bit = self.render_node(node, context) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/debug.py"" in render_node 80. return node.render(context) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/loader_tags.py"" in render 126. return compiled_parent._render(context) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in _render 142. return self.nodelist.render(context) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in render 844. bit = self.render_node(node, context) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/debug.py"" in render_node 80. return node.render(context) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/loader_tags.py"" in render 120. compiled_parent.nodelist.get_nodes_by_type(BlockNode)) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 854. nodes.extend(node.get_nodes_by_type(nodetype)) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 831. nodes.extend(nodelist.get_nodes_by_type(nodetype)) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 854. nodes.extend(node.get_nodes_by_type(nodetype)) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 831. nodes.extend(nodelist.get_nodes_by_type(nodetype)) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 854. nodes.extend(node.get_nodes_by_type(nodetype)) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 831. nodes.extend(nodelist.get_nodes_by_type(nodetype)) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 854. nodes.extend(node.get_nodes_by_type(nodetype)) ............................ File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 831. nodes.extend(nodelist.get_nodes_by_type(nodetype)) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 854. nodes.extend(node.get_nodes_by_type(nodetype)) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/base.py"" in get_nodes_by_type 829. nodelist = getattr(self, attr, None) File ""/home/venko/.pyvirtualenvs/django-max-recursion/local/lib/python2.7/site-packages/django/template/defaulttags.py"" in nodelist 298. return NodeList(node for _, nodelist in self.conditions_nodelists for node in nodelist) Exception Type: RuntimeError at /admin/ Exception Value: maximum recursion depth exceeded }}}" Bug closed Template system 1.7 Normal fixed Accepted 1 0 1 0 0 0