在Django Rest Fram的响应中包含中介(通过模型)

2024-03-28 23:24:42 发布

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我有一个关于在django rest框架中处理m2m/through模型及其表示的问题。举个典型的例子:

型号.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()

序列化程序.py:

imports...

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

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

视图.py:

imports...

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

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

在获取Member的实例时,我成功地接收了该成员的所有字段及其组,但是我只获取组的详细信息,而没有来自成员资格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
      }
   ]
}

注意连接日期。

我已经尝试了太多的解决方案,当然包括Django Rest-Framework official page about it,但似乎没有人给出一个正确的明确答案-我需要做什么来包含这些额外的字段?我发现DjangoTastypie更直截了当,但是有一些其他问题,我更喜欢使用rest框架。


Tags: djangonamepy框架restiddatemodel
3条回答

我遇到了这个问题,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dict列表,其中每个dict都是从membershipsserializer序列化的。要使其可写,可以在MemberSerializer中定义自己的create/update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。

注:作为一名软件工程师,我喜欢使用体系结构,并且我已经深入研究了分层开发方法,因此我将回答关于层的问题。

据我所知,这是解决办法 模型.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Data Access Layer,DataAccessLayer将从数据访问层返回经过筛选的对象,但是由于我必须快速回答问题,所以我调整了业务逻辑层中的代码!

不如。。。。。

在MemberSerializer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:

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', )

它的总体效果是创建一个序列化的值groups,它的源具有您想要的成员身份,然后它使用自定义序列化程序提取您想要显示的位。

编辑:正如@bryanph所评论的,在DRF 3.0中,serializers.field被重命名为serializers.ReadOnlyField,因此应该是:

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

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