title: Django form validation does not validate image
body: <p>I need validation Image field (requared) in form, but is not work. I do not get validation error in template.</p>
  <p>Image Form</p>
  <pre><code>class ImageForm(forms.ModelForm):
      class Meta:
          model = models.Image
          fields = ['title', 'image']
          name = forms.CharField(label='Title', max_length=100)
          image = forms.CharField(label='Image', max_length=100)
  
      def clean_title(self):
          title = self.cleaned_data.get(&quot;title&quot;)
          if not title:
              return forms.ValidationError(&quot;title is requared&quot;)
          else:
              return title
  
      def clean_image(self):
          image = self.cleaned_data.get(&quot;image&quot;)
          if not image:
              raise forms.ValidationError(&quot;No image!&quot;)
          else:
              return image
  </code></pre>
  <p>view.py</p>
  <pre><code>if form.is_valid():
          instance = form.save(commit=True)
          instance.save()
          return ImagesListView(request)
      else:
          return render(request, 'images/create.html', {'form': form})
  </code></pre>
  <p>Tenplate</p>
  <pre><code>  &lt;form action=&quot;{% url 'images:create' %}&quot; method=&quot;post&quot; enctype=&quot;multipart/form-data&quot;&gt;
              {% csrf_token %}
              &lt;table border=&quot;0&quot;&gt;
                  {{ form }}
              &lt;/table&gt;
              &lt;input class=&quot;btn bk-bs-btn-primary&quot; type=&quot;submit&quot; value=&quot;Загрузить изображение&quot;&gt;
          &lt;/form&gt;
  </code></pre>