编辑：我经过大量时间调试了回溯。看看答案的结尾。
我编写了一个自定义模板标记，用于检查网站上的特定组是否由用户添加书签，并根据该标记向html添加特定内容。
我写的tempplate标签如下。
def do_if_bookmarked(parser, token):
bits = token.contents.split()
if len(bits) != 3:
raise template.TemplateSyntaxError("%s tag takes two arguments" % bits[0])
nodelist_true = parser.parse(('else', 'endif_bookmarked'))
token = parser.next_token()
if token.contents == 'else':
nodelist_false = parser.parse(('endif_bookmarked',))
parser.delete_first_token()
else:
nodelist_false = template.NodeList()
return IfBookmarkedNode(bits[1], bits[2], nodelist_true, nodelist_false)
class IfBookmarkedNode(template.Node):
def __init__(self, user, pageuri, nodelist_true, nodelist_false):
self.nodelist_true = nodelist_true
self.nodelist_false = nodelist_false
self.user = template.Variable(user)
self.pageuri = template.Variable(pageuri)
def render(self, context):
try:
user = self.user.resolve(context)
pageuri = self.pageuri.resolve(context)
except template.VariableDoesNotExist:
return ' '
if BookmarkTag.objects.filter(user__pk=user.id,
pageuri=pageuri):
return self.nodelist_true.render(context)
else:
return self.nodelist_false.render(context)
register = template.Library()
register.tag('if_bookmarked', do_if_bookmarked)
和html部分是
{% if user.is_authenticated %}
{% if_bookmarked user pageuri %}
<p>you bookmared this</p>
{% else %}
<form method="post" {{bookmarkformaction}} >
details:<textarea rows="2" cols="20"name='bookmarkdetails'> </textarea>
name:<input type="text" id="id_bookmarkname" name='bookmarkname' value="" />
<input type="submit" name="add-bookmark" value="Add Bookmark" />
</form>
{% endif_bookmarked %}
{% else %}
<a href="/accounts/login/">login</a>
<a href="/accounts/register/">register</a>
{% endif %}
我知道回溯中的节点对象是“无”，但我很困惑如何解决这个问题。我在俯瞰什么？
如果信息不充分或问题不明确，请告诉我。我会根据需要修改它。
回溯：
Environment:
Request Method: GET
Request URL: http://localhost:8000/posttags/page/-EE-Btech/
Django Version: 1.3.1
Python Version: 2.7.2
Installed Applications:
['registration_defaults',
'django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
'django.contrib.messages',
'django.contrib.staticfiles',
'registration',
'debug_toolbar',
'postpots']
Installed Middleware:
('debug_toolbar.middleware.DebugToolbarMiddleware',
'django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware')
Traceback:
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
111. response = callback(request, *callback_args, **callback_kwargs)
File "/home/Qalqi/Projects/Python/Django/djangopath/postpots/views.py" in page
42. context_instance=RequestContext(request))
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django
/shortcuts/__init__.py" in render_to_response
20. return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/loader.py" in render_to_string
181. t = get_template(template_name)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/loader.py" in get_template
157. template, origin = find_template(template_name)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/loader.py" in find_template
134. source, display_name = loader(name, dirs)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/loader.py" in __call__
42. return self.load_template(template_name, template_dirs)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/loader.py" in load_template
48. template = get_template_from_string(source, origin, template_name)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/loader.py" in get_template_from_string
168. return Template(source, origin, name)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/debug_toolbar/panels/template.py" in new_template_init
37. old_template_init(self, template_string, origin, name)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/base.py" in __init__
108. self.nodelist = compile_string(template_string, origin)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/base.py" in compile_string
136. return parser.parse()
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/base.py" in parse
239. compiled_result = compile_func(self, token)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/defaulttags.py" in do_if
922. nodelist_true = parser.parse(('else', 'endif'))
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/base.py" in parse
243. self.extend_nodelist(nodelist, compiled_result, token)
File "/home/Qalqi/.virtualenvs/sandmaze/local/lib/python2.7/site-packages/django/template/debug.py" in extend_nodelist
58. node.source = token.source
Exception Type: AttributeError at /posttags/page/-EE-Btech/
Exception Value: 'NoneType' object has no attribute 'source'
编辑：发生此问题是因为do_if_bookmarked方法在某些情况下没有返回任何对象。确保你有一些beign返回的对象。
答案 0 :(得分：2)
也许尝试在这里使用简单的{％if％} +模板过滤器？通过这种方式，您可以避免构建复杂的标记代码，这将是类似的东西：
@register.filter
def bookmarked(user, page_uri):
return BookmarkTag.objects.filter(user__pk=user.id, pageuri=pageuri).count()
{% if user|bookmarked:page_uri %}{% else %}{% endif %}
恕我直言，阅读和调试更加清晰