Django Rest Framework nested relationship

Question

I'm new in using Django, I need your help

So, I created a model like this

models.py

from django.db import models

# Create your models here.
class Pegawai(models.Model):
    name = models.CharField(max_length=60)
    alias = models.CharField(max_length=60)
    def __str__(self):
        return self.name

class Barang(models.Model):
    pegawai = models.ForeignKey(Pegawai,on_delete=models.CASCADE,related_name='barangs',)
    nama_barang = models.CharField(max_length=60)
    harga_barang = models.CharField(max_length=60)
    def __str__(self):
        return self.pegawai.name

my serializer:

serializers.py

from rest_framework import serializers, fields

from .models import Pegawai,Barang


class BarangSerializer(serializers.ModelSerializer):
    class Meta:
        model = Barang
        fields = (
                'pegawai', 
                'nama_barang',
                'harga_barang',
                )

class PegawaiSerializer(serializers.ModelSerializer):
    barangs = BarangSerializer(read_only=True, many=True)
    class Meta:
        model = Pegawai
        fields = (
                'id',
                'name', 
                'alias',
                'barangs',
                )

my views:

views.py

from rest_framework import viewsets

from .serializers import PegawaiSerializer,BarangSerializer
from .models import Pegawai,Barang

class BarangViewSet(viewsets.ModelViewSet):
    queryset = Barang.objects.all().order_by('nama_barang')
    serializer_class = BarangSerializer

class PegawaiViewSet(viewsets.ModelViewSet):
    queryset = Pegawai.objects.all().order_by('name')
    serializer_class = PegawaiSerializer

Results:

{
    "id": 5,
    "name": "Ryan",
    "alias": "R",
    "barangs": [
        {
            "pegawai": 5,
            "nama_barang": "burjo",
            "harga_barang": "1234"
        },

Question: how can i change pegawai fields from id to name? like this:

{
    "id": 5,
    "name": "Ryan",
    "alias": "R",
    "barangs": [
        {
            "pegawai": Ryan,
            "nama_barang": "burjo",
            "harga_barang": "1234"
        },

I've searched some solutions but nothing works, I don't know where the problem is, so I need your guide. Cheers.

Saroj Rai · Accepted Answer · 2020-01-09 02:17:27Z

2

use serializers.CharField.

class BarangSerializer(serializers.ModelSerializer):
    pegawali=serializers.CharField(source="pegawali.name")
    class Meta:
        model = Barang
        fields = (
            'pegawai', 
            'nama_barang',
            'harga_barang',
            )

answered Jan 9, 2020 at 2:17

Saroj Rai

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Comments

JPG · Accepted Answer · 2020-01-09 03:28:12Z

1

Method-1

Since you are defined __str__() method in your Pegawai model, you can use StringRelatedField(...)

class BarangSerializer(serializers.ModelSerializer):
    pegawai = serializers.StringRelatedField()

    class Meta:
        model = Barang
        fields = (
            'pegawai',
            'nama_barang',
            'harga_barang',
        )

Method-2

use CharField

class BarangSerializer(serializers.ModelSerializer):
    pegawai = serializers.CharField(source='pegawai.name')

    class Meta:
        model = Barang
        fields = (
            'pegawai',
            'nama_barang',
            'harga_barang',
        )

UPDATE-1

To solve issues while creation of model objects, override the to_representation() method

class BarangSerializer(serializers.ModelSerializer):
    class Meta:
        model = Barang
        fields = (
            'pegawai',
            'nama_barang',
            'harga_barang',
        )

    def to_representation(self, instance):
        rep = super().to_representation(instance)
        rep['pegawai'] = instance.pegawai.name
        return rep

edited Jan 9, 2020 at 3:28

answered Jan 9, 2020 at 2:20

JPG

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4 Comments

ryanderon Over a year ago

This one is works.. but when i tried to input into Barang, i got errors like this: AssertionError: The .create() method does not support writable dotted-source fields by default. Write an explicit .create() method for serializer myapi.serializers.BarangSerializer, or set read_only=True on dotted-source serializer fields. Solution?

ryanderon Over a year ago

but how if I want to get all the Pegawai into the BarangSerializer?

JPG Over a year ago

Since your issue mentioned in the original post has been resolved, you should ask a new question.

ryanderon Over a year ago

stackoverflow.com/questions/59657005/… .. thanks

Linh Nguyen · Accepted Answer · 2020-01-09 02:13:19Z

0

You can change the fields value in serializer with DRF RelatedField:

class BarangSerializer(serializers.ModelSerializer):
    pegawai = serializers.RelatedField(source='pegawai.name', read_only=True)
    class Meta:
        model = Barang
        fields = (
                'pegawai', 
                'nama_barang',
                'harga_barang',
                )

answered Jan 9, 2020 at 2:13

Linh Nguyen

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Django Rest Framework nested relationship

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