title: Creating ModelForm with EmbeddedModelField and customize fields within EmbeddedModelField
body: <p>I have a model (parentmodel) which is having a EmbeddedModelField (embedmodel). This is basically a document in MongoDB. Below is the Model classes</p>
  
  <pre><code>class embedmodel(models.Model):
      sendto = models.CharField(max_length=10)
      sendtouser = models.CharField(max_length=15)
      sendtogroup = models.CharField(max_length=15)
  
      class parentmodel(models.Model):
      name = models.CharField(max_length=30, unique=True, primary_key=True)
      type = models.CharField(max_length=11)
      enabled = models.BooleanField()
      rule = models.EmbeddedModelField(model_container=embedmodel)
  
      class Meta:
          managed = False
          db_table = 'parentmodel'
  </code></pre>
  
  <p>And this is how my document in mongodb looks like</p>
  
  <pre><code>{
      'name': 'rule1',
      'type': 'static',
      'enabled': True,
      'rule': {
          'sendto': 'external',
          'sendtouser': 'sam',
          'sendtogroup': 'vendor'
      }
  }
  </code></pre>
  
  <p>I am trying to create a form which helps me create new rules and this is what i have in forms.py where i want to customize the form fields as well.</p>
  
  <pre><code>class RulesForm(forms.ModelForm):
      name = forms.CharField(max_length=30, required=True)
      type = forms.CharField(max_length=11, required=True)
      enabled = forms.BooleanField(widget=forms.CheckboxInput)
  
      class Meta:
          model = parentmodel
          fields = ['name', 'type', 'enabled', 'rule']
  </code></pre>
  
  <p>How to do customize the fields being displayed from embedmodel? I tried the below but no luck.</p>
  
  <pre><code>class RulesForm(forms.ModelForm):
      name = forms.CharField(max_length=30, required=True)
      type = forms.CharField(max_length=11, empty_value="UserDefined", required=True
      enabled = forms.BooleanField(widget=forms.CheckboxInput)
      sendto = forms.ChoiceField(widget=forms.Select, choices=[(1, 'External'), (2, 'Internal')])
      sendtouser = forms.CharField(max_length=30, required=False)
      sendtogroup = forms.CharField(max_length=30, required=False)
      class Meta:
          model = Rules
          fields = ['name', 'type', 'enabled', 'rule']
  </code></pre>
  
  <p>and</p>
  
  <pre><code>class RulesForm(forms.ModelForm):
      name = forms.CharField(max_length=30, required=True)
      type = forms.CharField(max_length=11, empty_value="UserDefined", required=True
      enabled = forms.BooleanField(widget=forms.CheckboxInput)
      embedmodel.sendto = forms.ChoiceField(widget=forms.Select, choices=[(1, 'External'), (2, 'Internal')])
      embedmodel.sendtouser = forms.CharField(max_length=30, required=False)
      embedmodel.sendtogroup = forms.CharField(max_length=30, required=False)
      class Meta:
          model = Rules
          fields = ['name', 'type', 'enabled', 'rule']
  </code></pre>