title: django-dynamic-formset: delete form then add form causes me problems
body: <p>Using jQuery Formset 1.3-pre</p>
  
  <p>If I use jquery-formset to delete an existing form, then on the same page add a new form and hit save, I get this error:</p>
  
  <pre><code>Request Method: POST
  Django Version: 1.7
  Exception Type: ValidationError
  Exception Value: ["'' value must be an integer."]
  </code></pre>
  
  <p>the value causing the error appears to be:</p>
  
  <pre><code>self    django.db.models.fields.AutoField: id
  </code></pre>
  
  <p>It only happens when new forms are added to replace deleted ones in the one formset session. If I delete, save, add, save, it's fine. Only when I delete, add, save do I get this error.</p>
  
  <p>I figure django uses the TOTAL-FORMS and INITIAL-FORMS variable to calculate whether it is dealing with new or pre-existing forms, but because my number of returned forms is the same as INITIAL-FORMS, even though one of the forms is a new one, it thinks all the forms are pre-existing ones and tries to validate the id. Something like that, anyway.</p>
  
  <p>Is there a way to prefix a new form to tell django it's dealing with an added form so it doesn't try to validate the  id?</p>
  
  <p>What am I missing?</p>
  
  <p>thanks</p>
  
  <p>John</p>
  
  <p>PS May be relevant, may not be: my jquery.formset delete routine uses ajax to remove from the database any rows that correspond to existing forms. I never found any documentation on dynamically deleting forms, so I just figured that was what I should do.</p>