python 在Django Rest框架中的响应中包含中介(通过模型)

qaxu7uf2  于 2023-02-02  发布在  Python
关注(0)|答案(4)|浏览(136)

我有一个关于如何处理m2m / through模型及其在django rest框架中的表现的问题,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

当获取一个Member示例时,我成功地接收到了成员的所有字段以及它的组-但是我只得到了组的详细信息,没有来自Membership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
      }
   ]
}

请注意加入日期
我已经尝试了很多解决方案,当然包括Django的REST框架官方页面,但似乎没有人给予一个合适的简单答案-我需要做什么来包含这些额外的字段?我发现使用Django-tastypie更直接,但有一些其他问题,更喜欢REST框架。

ih99xse1

ih99xse11#

不如...
在MemberSerializer上,定义一个字段,如下所示:

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

然后在你的成员序列化器上你可以创建这个:

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', )

这样做的总体效果是创建一个序列化值groups,它将所需的成员资格作为其源,然后使用自定义序列化程序提取要显示的位。
编辑:如@bryanph所述,在DRF 3.0中,serializers.field被重命名为serializers.ReadOnlyField,因此应为:

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

zpqajqem

zpqajqem2#

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Membership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]

这将返回组键的字典列表,其中每个字典都是从MembershipSerializer序列化的。若要使其可写,您可以在MemberSerializer中定义自己的创建/更新方法,在其中迭代输入数据并显式创建或更新成员资格模型示例。

w8ntj3qf

w8ntj3qf3#

我遇到了同样的问题,最后我用组查询集上的注解解决了这个问题。

from django.db.models import F    

class MemberSerializer(ModelSerializer):
    groups = serializers.SerializerMethodField()
    class Meta:
        model = Member
    def get_groups(self, instance):
        groups = instance.groups.all().annotate(join_date=F(membership__join_date))
        return GroupSerializer(groups, many=True).data

    
class GroupSerializer(ModelSerializer):
    join_date = serializers.CharField(required=False) # so the serializer still works without annotation
    class Meta:
        model = Group
        fields = ..., 'join_date']
dldeef67

dldeef674#

注意: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,所以我将回答关于层的问题。
据我所知,问题的解决方案如下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()

serializers.py

import serializer

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

CustomModels.py

imports...

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

BusinessLogic.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,您必须将请求传递到DataAccessLayer,DataAccessLayer将从数据访问层返回过滤的对象,但由于我必须以快速的方式回答问题,所以我调整了业务逻辑层中的代码!

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