When the object is nested, the SerializerMethodField doesn't get called.

[agconti]

When an object with a SerializerMethodField its accessed directly, its value gets added to the serialized output. However when an object is nested, its SerializerMethodField doesn't get called. (Supporting test in #3901)

Is this the intended behavior?

For example, a ProductGroup serializer has a SerializerMethodField that returns product logos. When accessed directly, those logos are populated:

[
    {
      "id": "c4f984f1-1021-4f6c-b68a-ddfa2c36610d",
      "description": " A description.",
      "logos": [
          "/media/product-logos/logo1.png",
          "/media/product-logos/logo2.jpg",
          "/media/product-logos/logo3.jpg"
      ],
      "products": [
          {
              "id": "1a671784-564e-44da-906c-a6af3b3cd484",
              "logo": "http://localhost:8000/media/product-logos/ps3.png",
          },
          {
              "id": "ff3b5fe6-993d-428d-8839-12491df9a657",
              "logo": "http://localhost:8000/media/product-logos/good-logos-5.jpg",
          },          
      ]
    }
]

When its nested in the response of a Dashboard serializer, its left out:

[
    {
        "id": "3ad323a5-fc34-4eec-8fef-01885b585779",
        "product_group": {
            "id": "c4f984f1-1021-4f6c-b68a-ddfa2c36610d",
            "description": " A description.",
             "products": [
                {
                    "id": "1a671784-564e-44da-906c-a6af3b3cd484",
                    "logo": "http://localhost:8000/media/product-logos/ps3.png",
                },
                {
                    "id": "ff3b5fe6-993d-428d-8839-12491df9a657",
                    "logo": "http://localhost:8000/media/product-logos/good-logos-5.jpg",
                },          
            ]
        }
    }
]

Using DRF 3.3.2, here's a setup to reproduce:

Serializers.py:

from rest_framework import serializers
from .models import Product, Issue, Dashboard


class ProductSerializer(serializers.ModelSerializer):

    class Meta:
        model = Product


class ProudctGroupSerializer(serializers.ModelSerializer):
    logos = serializers.SerializerMethodField()

    def get_logos(self, obj):
        return map(lambda p: p.logo.url, obj.products.all())

    class Meta:
        model = Issue


class DashBoardSerializer(serializers.ModelSerializer):

    class Meta:
        model = Dashboard
        depth = 3

models.py:

from __future__ import unicode_literals

import uuid
from django.db import models


class Product(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    logo = models.ImageField(upload_to="logos/")


class ProductGroup(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    description = models.TextField(max_length=80)
    products = models.ManyToManyField(Product)


class Dashboard(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    ProductGroup = models.OneToOneField(ProductGroup)

[FingerLiu]

@agconti what is going on with the issue, is it fixed now?

[tomchristie]

Milestoning for review.

[tomchristie]

Closing as per #3901.