如何让Django REST查询显示所有字段，含一对一关联表字段

我有两个Django模型，CustomUser和UserComputedInfo是一对一关联关系，现在用Django REST Framework创建API，当前只能返回CustomUser的字段，希望同时展示关联的UserComputedInfo的所有字段。

环境：Django v4、Python v3.9、Django REST framework、Windows 10

现有models.py #

from django.contrib.auth.models import AbstractUser
from django.db import models
from django.contrib.auth import get_user_model


class CustomUser(AbstractUser):
    email = models.EmailField(unique=True)
    post_code = models.DecimalField(max_digits=9, decimal_places=6)

    def __str__(self):
        return self.username


class UserComputedInfo(models.Model):
    user = models.OneToOneField(get_user_model(), on_delete=models.CASCADE)
    copy_input = models.DecimalField(max_digits=9, decimal_places=6)

    def __str__(self):
        return self.copy_input

现有serializers.py #

from rest_framework import serializers
from users.models import CustomUser


class CustomUserSerializer(serializers.ModelSerializer):
    class Meta:
        fields = ("email", "post_code")
        model = CustomUser

现有views.py #

from rest_framework import generics

from django.contrib.auth import get_user_model
from .serializers import CustomUserSerializer


class PostCodeAPIView(generics.ListAPIView):
    queryset = get_user_model().objects.all()
    serializer_class = CustomUserSerializer

要在API中同时返回一对一关联的UserComputedInfo字段，有两种简单实现方式：

方法一：嵌套Serializer #

先创建UserComputedInfo的序列化器，再在CustomUserSerializer中嵌套它：

修改后的serializers.py：

from rest_framework import serializers
from users.models import CustomUser, UserComputedInfo


class UserComputedInfoSerializer(serializers.ModelSerializer):
    class Meta:
        model = UserComputedInfo
        fields = "__all__"  # 也可指定具体字段，比如("copy_input",)


class CustomUserSerializer(serializers.ModelSerializer):
    # 一对一反向关联默认名称为模型名小写，即usercomputedinfo；若OneToOneField指定了related_name，需替换为对应名称
    usercomputedinfo = UserComputedInfoSerializer(read_only=True)

    class Meta:
        fields = ("email", "post_code", "usercomputedinfo")
        model = CustomUser

为避免N+1查询问题，需在视图的queryset中预取关联数据，修改views.py：

from rest_framework import generics

from django.contrib.auth import get_user_model
from .serializers import CustomUserSerializer


class PostCodeAPIView(generics.ListAPIView):
    queryset = get_user_model().objects.all().select_related('usercomputedinfo')
    serializer_class = CustomUserSerializer

方法二：直接指定字段来源 #

若仅需UserComputedInfo中的个别字段，可直接在CustomUserSerializer中通过source指定：

修改后的serializers.py：

from rest_framework import serializers
from users.models import CustomUser


class CustomUserSerializer(serializers.ModelSerializer):
    copy_input = serializers.DecimalField(source='usercomputedinfo.copy_input', read_only=True, max_digits=9, decimal_places=6)

    class Meta:
        fields = ("email", "post_code", "copy_input")
        model = CustomUser

同样需在视图的queryset中添加select_related('usercomputedinfo')优化查询性能。

内容的提问来源于stack exchange，提问作者user3848207