title: DRF Serializer not displaying fields (Foreign Key and many2many) in default HTML form page API. Field is available in GET
body: <p>DRF Serializer contains a group and inventory field which are many2many and foreign key. It is missing in default DRF HTML Form but available in GET view. currently, the depth field is enabled in Serializer. If i am removing depth then Foreign key is available in default HTML form, but still group many2many field is missing. I need both the fields for POST call or in DRF HTML Form.</p>
  
  <p>Do i have to write some create method, but I do not want to create new record for Foreign key and many2many just want to utilize the existing field.</p>
  
  <p>My Serializer class.</p>
  
  <pre><code>class MainHostSerializer(serializers.ModelSerializer):
      class Meta:
          model = MainHost
          fields = (
              'host_id', 
              'host_name',
              'inventory',
              'group'
          )  
          # depth = 2 
  </code></pre>
  
  <p>Raw view for default DRF HTML Form</p>
  
  <pre><code>{
      "host_id": null,
      "host_name": ""
  }
  </code></pre>
  
  <p>Model Class</p>
  
  <pre><code>class MainHost(models.Model):
      host_id =  models.IntegerField(verbose_name='HOST ID', primary_key=True)
      host_name =  models.CharField(verbose_name='HOST NAME', max_length=512)
      inventory = models.ForeignKey(related_name='inv_ins', on_delete=models.SET_NULL, to='hosts.MainInventory', blank=True, null=True)
      group = models.ManyToManyField(MainGroup, related_name='hostgroups', through ='HostGroup')
  </code></pre>