Passing the parent instance to a nested model serializer

[julianklotz]

Dear community,

I’m currently struggling with an issue around nested serializers. I’m trying to implement a linked data renderer (JSON-LD, Turtle, RDF-XML, etc.) for DRF. It’s going well for flat properties, but I’m struggling with nested presentations.

I’d like to create a nested serializer that doesn’t act on a specific attribute of the model instance, but the model instance itself.

Suppose you have an event model:

class Event(models.Model):
    date = models.DateField()

Using a ModelSerializer, this will give you a flat presentation of the date.

In linked data use cases, attributes are often described in a richer way, like this:

{
  "has_time_span": {
    "type": "Time_Span",
    "at_some_point_within": "1974-01-05"
   }
}

So what I’d like to do is this:

class DateSerializer(serializers.Serializer):
    type = serializer.CharField(default="Time_Span")
    at_some_point_within = serializers.DateField(source='date') <-- I need to access the parent event’s date attribute here.

class EventSerializer(serializers.ModelSerializer):
     has_time_span = DateSerializer(source='self') # <-- This doesn’t work, only attributes of the instance are passed to the serializer.

Any ideas?

I left out all the linked data parts in the example to make it easier to understand. Any help appreciated!

[julianklotz]

Ok, RTFM. Just pass source="*".