title: Override save method of Django Admin
body: <p>Well, I want to save any instance of a model without taking care about DDBB structure. So I decide to override <code>def save</code> in every model´s class. Kind of:</p>
  
  <pre><code>def save(self, force_insert=False, force_update=False, using=None, update_fields=None):
      if condition:
          raise Exception("You can´t insert that element")
      return super(name_class, self).save(self, force_insert=force_insert, force_update=force_update, using=using, update_fields=update_fields)
  </code></pre>
  
  <p>Well, with this I achieve to insert not raising an exception, but if the instance passes this check I want to insert in the DB whatever primary restriction exists...</p>
  
  <p>How can I get it?</p>
  
  <p>I suppose I must have to override the core code of <code>save</code>, but I checked it and I didn't find the part where I check the conditions for inserting in the DB.
  Maybe, The problem is only in the validation of the form. </p>
  
  <p>How can I override a specific form in Django Admin? Specifically, that one where I add, Delete or Edit one class of the model.</p>