title: Django JSONField to have particular keys
body: <p>My class looks like this:</p>
  
  <pre><code>class Foo(models.Model):
    known_by = JSONField()
  </code></pre>
  
  <p>My data looks like this</p>
  
  <pre><code>{ "known_by" : [
                  {'by':'name1', 'value':['def']},
                  {'by':'name2', 'value':['bar']}
                 ]
  }
  </code></pre>
  
  <p>Is there any way for me to enforce that the <code>Jsonfield</code> needs to follow the format of <code>by,value[]</code> dict. I know how to do this using <code>serialiazers</code></p>
  
  <p>Any other cleaner way to enforce this(in the model definition itself)? Thanks</p>