title: AttributeError: 'tuple' object has no attribute 'get'
body: <p>I have a problem in Django, I really don't know what the error is. The error happens in an <code>UpdateView</code> view, when putting several<code>input</code>s in the view, to know precisely where the error is, because I did not find it, the error does not happen in the view as such, I think it is the form :</p>
  
  <pre><code>class CourseForm(forms.ModelForm):
      class Meta:
          model = Course
          fields = ['title', 'subtitle', 'image', 'description', 'status']
  
          widgets = {
              'title': forms.TextInput(attrs = {'class': 'form-control', 'placeholder': 'Titulo'}),
              'subtitle': forms.TextInput(attrs = {'class': 'form-control', 'placeholder': 'Subtitulo'}),
              'image': forms.FileInput(attrs = {'class': 'custom-file-input'}),
              'description': forms.Textarea(attrs = {'class': 'form-control', 'placeholder': 'Descripcion'}),
              'status': forms.Select(attrs = {'class': 'custom-select'}),
          }
  
          labels = {'title': '', 'subtitle': '', 'image': '', 'description': ''}
  
      def __init__(self, *args, **kwargs):
          self.title_valid = False 
          if 'title_valid' in kwargs:
              self.title_valid = kwargs.pop('title_valid')
  
          super().__init__(args, kwargs)
  
      def clean_title(self):
          title = self.cleaned_data['title']
          if self.title_valid:
              if Course.objects.filter(title = title).exists():
                  raise forms.ValidationError('Ya existe un curso registrado con ese titulo, elige otro.')
  
          return title
  </code></pre>
  
  <p>I could also see that the <code>clean_title</code> method is not executed, layers there the error happens ...</p>
  
  <p>View:</p>
  
  <pre><code>class CourseUpdateView(UpdateView):
      model = Course
      form_class = CourseForm
      template_name = 'instructor/course_update_form.html'
      success_url = reverse_lazy('instructor:course:list')
      success_message = 'Se modificó con éxito el curso "{}".'
  
      def get_form(self, form_class = None):
          if form_class is None:
              form_class = self.get_form_class()
  
          form = form_class(**self.get_form_kwargs(), title_valid = True)
          for field in form.fields.keys():
              form.fields[field].required = False
  
          return form
  
      def form_valid(self, form):
          obj = form.save(commit = False)
          obj.slug = slugify(obj.title)
          obj.save()
  
          messages.success(self.request, self.success_message.format(obj.title))
          return redirect(self.success_url)
  </code></pre>
  
  <p>Complete error:</p>
  
  <pre><code>Watching for file changes with StatReloader
  Performing system checks...
  
  System check identified no issues (0 silenced).
  August 15, 2019 - 19:44:47
  Django version 2.2.2, using settings 'IBME.settings'
  Starting development server at http://127.0.0.1:8000/
  Quit the server with CONTROL-C.
  Internal Server Error: /instructor/course/curso-practico-de-django-aprende-creando-3-webs/update
  Traceback (most recent call last):
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/forms/forms.py", line 163, in __getitem__
      field = self.fields[name]
  KeyError: 'errors'
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 829, in _resolve_lookup
      current = current[bit]
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/forms/forms.py", line 169, in __getitem__
      ', '.join(sorted(f for f in self.fields)),
  KeyError: "Key 'errors' not found in 'CourseForm'. Choices are: description, image, status, subtitle, title."
  
  During handling of the above exception, another exception occurred:
  
  Traceback (most recent call last):
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/core/handlers/exception.py", line 34, in inner
      response = get_response(request)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/core/handlers/base.py", line 145, in _get_response
      response = self.process_exception_by_middleware(e, request)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/core/handlers/base.py", line 143, in _get_response
      response = response.render()
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/response.py", line 106, in render
      self.content = self.rendered_content
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/response.py", line 83, in rendered_content
      content = template.render(context, self._request)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/backends/django.py", line 61, in render
      return self.template.render(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 171, in render
      return self._render(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 163, in _render
      return self.nodelist.render(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 937, in render
      bit = node.render_annotated(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 904, in render_annotated
      return self.render(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/loader_tags.py", line 150, in render
      return compiled_parent._render(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 163, in _render
      return self.nodelist.render(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 937, in render
      bit = node.render_annotated(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 904, in render_annotated
      return self.render(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/loader_tags.py", line 62, in render
      result = block.nodelist.render(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 937, in render
      bit = node.render_annotated(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 904, in render_annotated
      return self.render(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/defaulttags.py", line 302, in render
      match = condition.eval(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/defaulttags.py", line 876, in eval
      return self.value.resolve(context, ignore_failures=True)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 671, in resolve
      obj = self.var.resolve(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 796, in resolve
      value = self._resolve_lookup(context)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/template/base.py", line 837, in _resolve_lookup
      current = getattr(current, bit)
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/forms/forms.py", line 180, in errors
      self.full_clean()
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/forms/forms.py", line 381, in full_clean
      self._clean_fields()
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/forms/forms.py", line 393, in _clean_fields
      value = field.widget.value_from_datadict(self.data, self.files, self.add_prefix(name))
    File "/home/lcteen/miniconda3/envs/django/lib/python3.7/site-packages/django/forms/widgets.py", line 258, in value_from_datadict
      return data.get(name)
  AttributeError: 'tuple' object has no attribute 'get'
  </code></pre>