在Django Rest框架中的回应中包含中介（通过模型）

问题描述

我有一个关于在django休息框架中处理m2m / through模型及其演示的问题。我们来看一个典型的例子：

models.py：

  from django.db import models 
 
 class成员（models.Model）：
 name = models.CharField（max_length = 20）
 groups = models.ManyToManyField（'Group'，through ='Membership'）
 
 class Group（models.Model）：
 name = models.CharField（max_length = 20）
 
 class成员资格（models.Model） ：
 member = models.ForeignKey（'Member'）
 group = models.ForeignKey（'Group'）
 join_date = models.DateTimeField（）
  

serializers.py：

  
 
 class MemberSerializer（ModelSerializer）：
 class Meta：
 model = Member 
 
 class GroupSerializer（ModelSerializer）：
 class Meta： 
 model = Group 
  

views.py：

  imports ... 
 
 class MemberViewSet（ModelViewSet）：
 queryset = Mem ber.objects.all（）
 serializer_class = MemberSerializer 
 
 class GroupViewSet（ModelViewSet）：
 queryset = Group.objects.all（）
 serializer_class = GroupSerializer 
  

当获取成员的实例时，我成功地收到了所有成员的字段及其组 - 但是我只有

换句话说，我 expect 可以收到：

  {
'id'：2，
'name'：'some member'，
'groups '：[
 {
'id'：55，
'name'：'group 1'
'join_date'：34151564 
}，
 { 
'id'：56，
'name'：'group 2'
'join_date'：11200299 
} 
] 
} 
  

请注意 join_date 。

$ b $我尝试过这么多的解决方案，包括当然，没有人似乎给出了一个正确的答案 - 我需要做什么来包括这些额外的字段？我发现它更直接与django-tastypie但有一些其他问题，并喜欢休息框架。

解决方案

如何。 ....

在您的MemberSerializer上，定义一个字段，如：

  groups = MembershipSerializer（source ='membership_set'，many = True）
  

然后你的会员序列化器你可以创建这个：

  class MembershipSerializer（serializers.HyperlinkedModelSerializer）：
 
 id = serializers.Field（source ='group.id'）
 name = serializers.Field（source ='group.name'）
 
 class Meta：
 model = Membership 
 
 fields =（'id'，'name'，'join_date'）
  

这具有创建一个序列化值的组合的整体效果，组作为其所需的成员资源，然后使用自定义序列化器来提取所需的位o显示。

编辑：由@bryanph评论， serializers.field 已重命名为 serializer.ReadOnlyField 在DRF 3.0中，所以这应该是：

  class MembershipSerializer（serializers.HyperlinkedModelSerializer ）
 
 id = serializers.ReadOnlyField（source ='group.id'）
 name = serializers.ReadOnlyField（source ='group.name'）
 
 Meta：
 model = Membership 
 
 fields =（'id'，'name'，'join_date'）
  

任何现代化的实现

I have a question about dealing with m2m / through models and their presentation in django rest framework. Let's take a classic example:

models.py:

from django.db import models

class Member(models.Model):
    name = models.CharField(max_length = 20)
    groups = models.ManyToManyField('Group', through = 'Membership')

class Group(models.Model):
    name = models.CharField(max_length = 20)

class Membership(models.Model):
    member = models.ForeignKey('Member')
    group = models.ForeignKey('Group')
    join_date = models.DateTimeField()

serializers.py:

imports...

class MemberSerializer(ModelSerializer):
    class Meta:
        model = Member

class GroupSerializer(ModelSerializer):
    class Meta:
        model = Group

views.py:

imports...

class MemberViewSet(ModelViewSet):
    queryset = Member.objects.all()
    serializer_class = MemberSerializer

class GroupViewSet(ModelViewSet):
    queryset = Group.objects.all()
    serializer_class = GroupSerializer

When GETing an instance of Member, I successfully receive all of the member's fields and also its groups - however I only get the groups' details, without extra details that comes from the Membership model.

In other words I expect to receive:

{
   'id' : 2,
   'name' : 'some member',
   'groups' : [
      {
         'id' : 55,
         'name' : 'group 1'
         'join_date' : 34151564
      },
      {
         'id' : 56,
         'name' : 'group 2'
         'join_date' : 11200299
      }
   ]
}

Note the join_date.

I have tried oh so many solutions, including of course Django Rest-Framework official page about it and no one seems to give a proper plain answer about it - what do I need to do to include these extra fields? I found it more straight-forward with django-tastypie but had some other problems and prefer rest-framework.

解决方案

How about.....

On your MemberSerializer, define a field on it like:

groups = MembershipSerializer(source='membership_set', many=True)

and then on your membership serializer you can create this:

class MembershipSerializer(serializers.HyperlinkedModelSerializer):

    id = serializers.Field(source='group.id')
    name = serializers.Field(source='group.name')

    class Meta:
        model = Membership

        fields = ('id', 'name', 'join_date', )

That has the overall effect of creating a serialized value, groups, that has as its source the membership you want, and then it uses a custom serializer to pull out the bits you want to display.

EDIT: as commented by @bryanph, serializers.field was renamed to serializers.ReadOnlyField in DRF 3.0, so this should read:

class MembershipSerializer(serializers.HyperlinkedModelSerializer):

    id = serializers.ReadOnlyField(source='group.id')
    name = serializers.ReadOnlyField(source='group.name')

    class Meta:
        model = Membership

        fields = ('id', 'name', 'join_date', )

for any modern implementations

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