django序列化器嵌套

The Django Rest Framework (DRF) is one of the effectively written frameworks around Django and helps build REST APIs for an application back-end.

Django Rest Framework( DRF )是围绕Django编写的有效框架之一，可帮助为应用程序后端构建REST API。

I was using it in one of my personal projects and stumbled upon this challenge of “serializing a model which is referencing another model via OneToOne field.”

我在自己的一个个人项目中使用了它，却偶然遇到了“串行化通过OneToOne字段引用另一个模型的模型”这一挑战。

`I was using the User model from django.contrib.auth.models. I wanted to write an API to create and update a user object through a single API which also updates my model’s attributes. The solution was to use DRF’s Nested Relationships in serialization.

`我正在使用django.contrib.auth.models的User模型。 我想编写一个API，以通过一个API创建和更新用户对象，该API还可以更新模型的属性。 解决方案是在序列化中使用DRF的嵌套关系 。

I shall assume you have a fair working knowledge of Python, virtualenv, pip, Django and DRF before proceeding. If not, please learn more and feel free to return if you are ever stuck on nested relationships in serialization.

在继续之前，我将假定您对Python，virtualenv，pip，Django和DRF具有一定的了解。 如果不是，请了解更多信息，如果您在序列化过程中陷入嵌套关系中，请随时返回。

The example I am considering here is a University Student model, referencing User model via the OneToOne field. My goal is a single API for creating and getting user details like name, username, and email along with a student attribute such as subject major.

我在这里考虑的示例是一个大学学生模型，通过OneToOne字段引用用户模型。 我的目标是创建和获取用户详细信息(例如姓名，用户名和电子邮件)以及学生属性(例如专业)的单一API。

Here is how my models.py looks:

这是我的models.py外观：

from django.db import models
from django.contrib.auth.models import Userclass UnivStudent(models.Model):"""A class based model for storing the records of a university studentNote: A OneToOne relation is established for each student with User model."""user = models.OneToOneField(User)subject_major = models.CharField(name="subject_major", max_length=60)

Next, the serializer for the above model determines the attributes to manipulate. If you observe below, I have 2 serializer classes, UserSerializer and StudentSerializer. This is our point of interest.

接下来，上述模型的序列化程序确定要操作的属性。 如果您在下面观察，我有2个序列化程序类UserSerializer 和StudentSerializer 。 这是我们的兴趣点。

I have declared a user attribute which is a serializer field here. That user attribute will primarily hold the entire reference for the UserSerializer class. In the fields of StudentSerializer , we just see ‘user’ and ‘subject_major’. This allows us to enter the student (or user) attributes along with the subject_major.

我在这里声明了一个user属性，它是一个序列化器字段。 该user属性将主要保存UserSerializer类的整个引用。 在StudentSerializer的字段中，我们只看到' user '和' subject_major '。 这使我们能够与subject_major一起输入学生(或用户)属性。

A user entry is created which is referenced by the student entry. We override the create method of StudentSerializer to create a user object first, and use that to create the student object.

创建一个用户条目，该条目由学生条目引用。 我们重写StudentSerializer的create方法来首先创建一个user对象，然后使用它来创建student对象。

The serializer.py is as follows:

serializer.py如下：

from rest_framework import serializers, status
from models import *class UserSerializer(serializers.ModelSerializer):class Meta:model = Userfields = ('username', 'first_name', 'last_name', 'email')class StudentSerializer(serializers.ModelSerializer):"""A student serializer to return the student details"""user = UserSerializer(required=True)class Meta:model = UnivStudentfields = ('user', 'subject_major',)def create(self, validated_data):"""Overriding the default create method of the Model serializer.:param validated_data: data containing all the details of student:return: returns a successfully created student record"""user_data = validated_data.pop('user')user = UserSerializer.create(UserSerializer(), validated_data=user_data)student, created = UnivStudent.objects.update_or_create(user=user,subject_major=validated_data.pop('subject_major'))return student

The views.py should be quite straightforward if you are already familiar with the class-based views of Django. We will be using the serializer to validate and create the model objects:

如果您已经熟悉Django 的基于类的视图 ，则views.py应该非常简单。 我们将使用序列化程序来验证和创建模型对象：

from serializers import *
from models import *
from rest_framework.views import APIView
from rest_framework.response import Response
from rest_framework import statusclass StudentRecordView(APIView):"""A class based view for creating and fetching student records"""def get(self, format=None):"""Get all the student records:param format: Format of the student records to return to:return: Returns a list of student records"""students = UnivStudent.objects.all()serializer = StudentSerializer(students, many=True)return Response(serializer.data)def post(self, request):"""Create a student record:param format: Format of the student records to return to:param request: Request object for creating student:return: Returns a student record"""serializer = StudentSerializer(data=request.data)if serializer.is_valid(raise_exception=ValueError):serializer.create(validated_data=request.data)return Response(serializer.data, status=status.HTTP_201_CREATED)return Response(serializer.error_messages,status=status.HTTP_400_BAD_REQUEST)

I have included /univstud/ url for achieving post and get requests for university student.

我已经包含了/univstud/ url用于获取post并get针对大学生的请求。

from django.conf.urls import patterns, include, url
from django.contrib import admin
from rest_framework import routers
from rest_framework.urlpatterns import format_suffix_patterns
from OneToOne import viewsadmin.autodiscover()
router = routers.DefaultRouter()urlpatterns = patterns('',url(r'^admin/', include(admin.site.urls)),url(r'^api-auth/', include('rest_framework.urls',namespace='rest_framework')),
)urlpatterns += format_suffix_patterns([# API to map the student recordurl(r'^api/univstud/$',views.StudentRecordView.as_view(),name='students_list'),
])

The POST request call would look something like this:

POST请求调用如下所示：

The Get request call would look something like this:

Get请求调用看起来像这样：

That’s all!:)

就这样！：)

Nested Relationship is thus enabled on StudentSerializer to reference user.

因此，在StudentSerializer上启用了嵌套关系来引用user 。

Complete code is in my gitlab repository.

完整的代码在我的gitlab存储库中。

参考文献： (References:)

1. http://www.django-rest-framework.org/api-guide/relations/

   http://www.django-rest-framework.org/api-guide/relations/

翻译自: https://www.freecodecamp.org/news/nested-relationships-in-serializers-for-onetoone-fields-in-django-rest-framework-bdb4720d81e6/

django序列化器嵌套