提问者:小点点

在Django Rest框架的响应中包含中介(通过模型)


我有一个关于处理 m2m / 通过模型及其在 django rest 框架中的呈现的问题。让我们举一个经典的例子:

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

当获取成员的实例时,我成功地接收到了成员的所有字段及其组——但是我只获得了组的详细信息,没有来自成员模型的额外详细信息。

换句话说,我希望收到:

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

注意join_date。

我已经尝试了很多解决方案,当然包括Django REST-Framework官方页面,似乎没有人给出一个合适的简单答案——我需要做些什么来包含这些额外的字段?我发现django tasty我用django tastyby更直接,但有一些其他问题,更喜欢rest-Framework。


共3个答案

匿名用户

怎么样.....

在成员序列化程序上,定义一个字段,如下所示:

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

然后在您的成员资格序列化程序上,您可以创建以下内容:

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', )

这样做的总体效果是创建一个序列化值groups,它以您想要的成员身份作为其源,然后它使用一个自定义序列化程序来提取您想要显示的位。

编辑:正如@bryanph所评论的,serializers.field在DRF 3.0中被重命名为序列化程序。ReadOnlyfield,所以这应该是:

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', )

对于任何现代实现

匿名用户

我正面临这个问题,我的解决方案(使用DRF 3.6)是在对象上使用SerializerMethodField,并显式查询成员资格表,如下所示:

class MembershipSerializer(serializers.ModelSerializer):
    """Used as a nested serializer by MemberSerializer"""
    class Meta:
        model = Membership
        fields = ('id','group','join_date')

class MemberSerializer(serializers.ModelSerializer):
    groups = serializers.SerializerMethodField()

    class Meta:
        model = Member
        fields = ('id','name','groups')

    def get_groups(self, obj):
        "obj is a Member instance. Returns list of dicts"""
        qset = Membership.objects.filter(member=obj)
        return [MembershipSerializer(m).data for m in qset]

这将返回groups键的字典列表,其中每个字典都是从MembershipSerializer序列化的。要使它可写,可以在MemberSerializer中定义自己的创建/更新方法,在该方法中迭代输入数据并显式创建或更新成员资格模型实例。

匿名用户

注意:作为一名软件工程师,我喜欢使用架构,并且我已经深入研究了分层开发方法,所以我将从层的角度来回答这个问题。

据我了解,这是解决方案 models.py

class Member(models.Model):
    member_id = models.AutoField(primary_key=True)
    member_name = models.CharField(max_length = 

class Group(models.Model):
    group_id = models.AutoField(primary_key=True)
    group_name = models.CharField(max_length = 20)
    fk_member_id = models.ForeignKey('Member', models.DO_NOTHING, 
                             db_column='fk_member_id', blank=True, null=True)

class Membership(models.Model):
    membershipid = models.AutoField(primary_key=True)
    fk_group_id = models.ForeignKey('Group', models.DO_NOTHING, 
                             db_column='fk_member_id', blank=True, null=True)
    join_date = models.DateTimeField()

序列化程序.py

import serializer

class AllSerializer(serializer.Serializer):
    group_id = serializer.IntegerField()
    group_name = serializer.CharField(max_length = 20)
    join_date = serializer.DateTimeField()

自定义模型. py

imports...

    class AllDataModel():
        group_id = ""
        group_name = ""
        join_date = ""

业务逻辑.py

imports ....
class getdata(memberid):
    alldataDict = {}
    dto = []
    Member = models.Members.objects.get(member_id=memberid) #or use filter for Name
    alldataDict["MemberId"] = Member.member_id
    alldataDict["MemberName"] = Member.member_name
    Groups = models.Group.objects.filter(fk_member_id=Member)
    for item in Groups:
        Custommodel = CustomModels.AllDataModel()
        Custommodel.group_id = item.group_id
        Custommodel.group_name = item.group_name
        Membership = models.Membership.objects.get(fk_group_id=item.group_id)
        Custommodel.join_date = Membership.join_date
        dto.append(Custommodel)
    serializer = AllSerializer(dto,many=True)
    alldataDict.update(serializer.data)
    return alldataDict

从技术上讲,您必须将请求传递给DataAccessLayer,它将从数据访问层返回过滤后的对象,但是由于我必须以快速的方式回答这个问题,所以我调整了业务逻辑层的代码!