使用 viewsets.ModelViewSet 视图更新 Django rest 框架 model 中的外键

Question

I am relatively new to DRF and having hard time updating the foreign key in my model via POST request.

    # Model for Event.

        class Event(models.Model):
              heading = models.TextField()
              event_construction_site = models.ForeignKey(
                  ConstructionSite, on_delete=models.CASCADE, related_name='construction_site_events', null=True)
            
              def __str__(self):
                  return str(self.id)
    
    
        class ConstructionSiteShortSerializer(serializers.ModelSerializer):
            class Meta:
                model = ConstructionSite
                fields = ['id']
    
     # Serializer for Event.

        class EventSerializer(serializers.ModelSerializer):
            event_construction_site = ConstructionSiteShortSerializer()
            event_posted_by = CustomUserSerializer()
        
            class Meta:
                model = Event
                fields = ('id', 'heading', 'event_construction_site')

Structure of my GET response is as follows:

  {
    id: 1,
    heading: "Truck with formwork arrived",
    event_construction_site: {
      id: 3
    }
  }

My concern here is how can I update the id of event_construction_site ?

I tried updating it like as follows:

{
    "heading": "a",
    "event_construction_site": {"id": 2}
}

Dute to id of event_construction_site being nested field I get an error that says =>

The `.create()` method does not support writable nested fields by default.

Answer 1

You can use a PrimaryKeyRelatedField.

class EventSerializer(serializers.ModelSerializer):
            event_construction_site = serializers.PrimaryKeyRelatedField(queryset=ConstructionSite.objects.all())
            event_posted_by = CustomUserSerializer()
        
            class Meta:
                model = Event
                fields = ('id', 'heading', 'event_construction_site')