title: I get MerchantGroupFilter' object is not iterable using django-filter
body: <p>I'm trying to set up a simple filter using django-filter. I've done this before and it worked, so not able to figure out whats gone wrong this time. The error I get is <code>MerchantGroupFilter' object is not iterable</code>.</p>
  
  <p>models.py</p>
  
  <pre><code>class MerchantGroup(models.Model):
      created = models.DateTimeField(null=False, blank=False, default=timezone.now)
      name = models.CharField(max_length=100, null=False, blank=False)
      ledger = models.ForeignKey('journal.Ledger', on_delete=models.PROTECT, null=True, blank=True)
  </code></pre>
  
  <p>filters.py</p>
  
  <pre><code>import django_filters
  from monzo.forms import DateTypeInput
  from journal.models import Ledger
  from .models import MerchantGroup
  # from monzo.models import # Duplicate of the above?
  
  class MerchantGroupFilter(django_filters.FilterSet):
  
      class Meta:
          model = MerchantGroup
          # Fields list needs to be present for FilterSet to work
          fields = ['ledger']
  </code></pre>
  
  <p>views.py</p>
  
  <pre><code>@login_required
  def merchantgroups_show_all(request):
      merchant_groups = MerchantGroupFilter(request.GET, queryset=MerchantGroup.objects.all())
  
      #merchant_groups2 = paginator.get_page(page)
      return render(request, 'monzo/merchantgroups_show_all.html', {'merchant_groups': merchant_groups,})
  </code></pre>
  
  <p>Traceback</p>
  
  <pre><code>Environment:
  
  
  Request Method: GET
  Request URL: http://localhost/monzo/merchantgroups/show/all/
  
  Django Version: 3.0.5
  Python Version: 3.8.2
  Installed Applications:
  ['monzo',
   'rest_framework',
   'django.contrib.humanize',
   'journal',
   'adminsortable2',
   'widget_tweaks',
   'django.contrib.admin',
   'django.contrib.auth',
   'django.contrib.contenttypes',
   'django.contrib.sessions',
   'django.contrib.messages',
   'django.contrib.staticfiles']
  Installed Middleware:
  ['django.middleware.security.SecurityMiddleware',
   'whitenoise.middleware.WhiteNoiseMiddleware',
   'django.contrib.sessions.middleware.SessionMiddleware',
   'django.middleware.common.CommonMiddleware',
   'django.middleware.csrf.CsrfViewMiddleware',
   'django.contrib.auth.middleware.AuthenticationMiddleware',
   'django.contrib.messages.middleware.MessageMiddleware',
   'django.middleware.clickjacking.XFrameOptionsMiddleware']
  
  
  Template error:
  In template C:\Users\Philip\CodeRepos\Acacia2\templates\template.html, error at line 0
     'MerchantGroupFilter' object is not iterable
     1 : &lt;!doctype html&gt;
     2 : &lt;html lang="en"&gt;
     3 :     &lt;head&gt;
     4 :         &lt;!-- Required meta tags --&gt;
     5 :         &lt;meta charset="utf-8"&gt;
     6 :         &lt;meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"&gt;
     7 : 
     8 :         &lt;!-- Basic Bootstrap CSS and Javascript --&gt;
     9 :         &lt;link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" crossorigin="anonymous"&gt;
     10 : 
  
  
  Traceback (most recent call last):
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\core\handlers\exception.py", line 34, in inner
      response = get_response(request)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\core\handlers\base.py", line 115, in _get_response
      response = self.process_exception_by_middleware(e, request)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\core\handlers\base.py", line 113, in _get_response
      response = wrapped_callback(request, *callback_args, **callback_kwargs)
    File "C:\Users\Philip\AppData\Local\Programs\Python\Python38-32\lib\contextlib.py", line 75, in inner
      return func(*args, **kwds)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\contrib\auth\decorators.py", line 21, in _wrapped_view
      return view_func(request, *args, **kwargs)
    File "C:\Users\Philip\CodeRepos\Acacia2\monzo\views.py", line 54, in merchantgroups_show_all
      return render(request, 'monzo/merchantgroups_show_all.html', {'merchant_groups': merchant_groups,})
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\shortcuts.py", line 19, in render
      content = loader.render_to_string(template_name, context, request, using=using)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\loader.py", line 62, in render_to_string
      return template.render(context, request)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\backends\django.py", line 61, in render
      return self.template.render(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\base.py", line 171, in render
      return self._render(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\base.py", line 163, in _render
      return self.nodelist.render(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\base.py", line 936, in render
      bit = node.render_annotated(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\base.py", line 903, in render_annotated
      return self.render(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\loader_tags.py", line 150, in render
      return compiled_parent._render(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\base.py", line 163, in _render
      return self.nodelist.render(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\base.py", line 936, in render
      bit = node.render_annotated(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\base.py", line 903, in render_annotated
      return self.render(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\loader_tags.py", line 62, in render
      result = block.nodelist.render(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\base.py", line 936, in render
      bit = node.render_annotated(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\base.py", line 903, in render_annotated
      return self.render(context)
    File "C:\Users\Philip\CodeRepos\Acacia2\venv\lib\site-packages\django\template\defaulttags.py", line 165, in render
      values = list(values)
  
  Exception Type: TypeError at /monzo/merchantgroups/show/all/
  Exception Value: 'MerchantGroupFilter' object is not iterable
  </code></pre>