VariableDoesNotExist: Failed lookup for key [text] in ‘None’

Tags: django

VariableDoesNotExist: Failed lookup for key [text] in 'None', that was the error that I got out of an internal django app that I wrote. The app is the most error-free one that I ever build, so I was quite surprised.

I was even more surprised when I started debugging it. The error was in the search functionality. Searching for “lizard” would give an “error 500” page. Searching for “lizar” gave 0 results (which is fine), for “lizardd”, too. “lidard” also gave 0 results. Only a search for “lizard” crashed the site.

Huh? Weird. I got the question whether I put a hidden message into this app (as “lizard” is one of our main products) :-)

Locally it all worked fine, of course. Only on the server did I see the error.

Here’s the relevant part of the traceback:

Stacktrace (most recent call last):
File "django/core/handlers/", line 112, in get_response
  response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "haystack/", line 50, in __call__
  return self.create_response()
File "haystack/", line 144, in create_response
  return render_to_response(self.template, context, context_instance=self.context_class(self.request))
File "django/shortcuts/", line 29, in render_to_response
  return HttpResponse(loader.render_to_string(*args, **kwargs), **httpresponse_kwargs)
File "django/template/", line 169, in render_to_string
  return t.render(context_instance)
File "django/template/", line 140, in render
  return self._render(context)
File "django/template/", line 840, in render
  bit = self.render_node(node, context)
File "django/template/", line 78, in render_node
  return node.render(context)
File "django/template/", line 196, in render
File "haystack/templatetags/", line 30, in render
  text_block = self.text_block.resolve(context)
File "django/template/", line 735, in resolve
  value = self._resolve_lookup(context)
File "django/template/", line 781, in _resolve_lookup
  (bit, current))  # missing attribute

Eventually I found it. Via this django-haystack post. Haystack, which I use for searching, by default doesn’t deal with deleted objects. And, of course, yesterday I removed an object via the admin interface. A project with “lizard” in the title. Normally nothing is removed in this app, so the problem didn’t surface earlier.

Haystack’s results include the deleted now-non-existing object, which crashes the template. Which is a little bit weird, as normally django’s template layer is quite forgiving about None. It might be the {% highlight %} templatetag that I’m using.

Anyway, the solution is to run the update_index command with the --remove option. Or run rebuild_index. The second replaces the index, but is quicker. The first takes more resources, but leaves the index in place. Take whatever fits your usecase best. logo

About me

My name is Reinout van Rees and I work a lot with Python (programming language) and Django (website framework). I live in The Netherlands and I'm happily married to Annie van Rees-Kooiman.

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