title: Debugging Django Forms validation errors
body: <p>One of my forms fails on form.is_valid()</p>
  
  <p>First time I debug a Django form so I am not too sure where to look</p>
  
  <p>forms.py</p>
  
  <pre><code>class ImageForm(forms.ModelForm):
  def __init__(self,user,*args,**kwargs):
      super(ImageForm,self ).__init__(*args,**kwargs) # populates the form
  
  class Meta:
      model = KMSImageP
      fields = ('name',
                'caption',
                'image',
                )
  </code></pre>
  
  <p>models.py</p>
  
  <pre><code>from photologue.models import ImageModel
  
  class KMSImageP(ImageModel):
  
  name = models.CharField(max_length=100)
  slug = AutoSlugField(max_length=45, unique=True, populate_from='name')
  num_views = models.PositiveIntegerField(editable=False, default=0)
  caption = models.TextField(_('caption'), blank
  </code></pre>
  
  <p>I got that</p>
  
  <pre><code>&gt;&gt;&gt;&gt; image_form.__dict__['_errors']
  &gt;&gt;&gt;&gt;django.forms.util.ErrorDict({'image': django.forms.util.ErrorList([&lt;django.utils.functional.__proxy__ object at 0xecc770&gt;])})
  </code></pre>
  
  <p>So I am guessing that my 'image' field (an ImageField inherited from an abstract base class) is the cause of the failure but I don't know why.</p>
  
  <p>I've tried changing the type of the attributes to FileField (as my other forms use FileField to upload with no problem) but it still fails... Anyhow, I am clueless...</p>