Django Rest Framework嵌套的序列化器未显示相关数据 [英] Django Rest Framework nested serializer not showing related data

问题描述

我使用Django Rest框架进行了基本设置。我有两个模型和一个嵌套的序列化程序设置：

I have a basic setup using the Django Rest Framework. I have two models and a nested serializer setup:

# models.py

from django.db import models

class Plan(models.Model):
    name = models.CharField(max_length='100')

    def __unicode__(self):
        return u'%s' % (self.name)

class Group(models.Model):
    plan = models.ForeignKey('plan')
    name = models.CharField(max_length='50')
    weight = models.SmallIntegerField()

    def __unicode__(self):
        return u'%s - %s' % (self.name, self.plan.name)


# serializer.py

from plans.models import Plan, Group
from rest_framework import serializers

class GroupSerializer(serializers.ModelSerializer):
    class Meta:
        model = Group
        fields = ('name', 'weight')

class PlanSerializer(serializers.ModelSerializer):
    group = GroupSerializer(many=True, read_only=True)

    class Meta:
        model = Plan
        fields = ('name', 'group')


# views.py

from rest_framework import viewsets

from plans.models import Plan
from plans.serializers import PlanSerializer

class PlanViewSet(viewsets.ModelViewSet):
    queryset = Plan.objects.all()
    serializer_class = PlanSerializer

当我在Django Shell中查看序列化程序关系时，它正确显示了该关系：

When I view the serializers relationships in Django's Shell it shows the relationship correctly:

PlanSerializer():
name = CharField(max_length='100')
group = GroupSerializer(many=True, read_only=True):
    name = CharField(max_length='50')
    weight = IntegerField()

我最终通过cURL回来的是：

What I end up getting back via cURL is:

[
    {
        name: Test Plan
    }
]

我做什么预计会回来的是：

What I expect to get back is:

[
    {
        name: Test Plan,
        group: [
                {
                    name: Test Group,
                    weight: 1
                }
        ] 
    }
]

没有嵌套数据通过。我对此处未正确设置的内容感到困惑。有人可以指出我正确的方向吗？

There is no nested data coming through. I'm at a lose for what I've not setup correctly here. Can anyone point me in the correct direction?

推荐答案

问题出在您的 queryset ： queryset = Plan.objects.all（）。此查询集中中的所有项目都不具有 .group 属性，这就是为什么结果为空的原因。默认情况下，Django创建 plan ForeignKey的反向关系，称为 group_set （除非您不通过<$重命名） c $ c> related_name ）（这意味着查询集中计划项c>具有 group_set 属性，该属性是一个查询集，包含此计划）的所有组。您可以使用此属性以获得正确的序列化。这意味着要更改：

The problem comes from your queryset: queryset = Plan.objects.all(). None of the items in this queryset has .group attribute that's why your result is empty. By default Django creates a reverse relation of the plan ForeignKey called group_set (unless you don't rename it via related_name) (this means that every plan item in the queryset have a group_set attribute which is a queryset containing all the groups of this plan). You can use this attribute in order to get a proper serialization. This means to change:

class PlanSerializer(serializers.ModelSerializer):
    group_set = GroupSerializer(many=True, read_only=True)

    class Meta:
        model = Plan
        fields = ('name', 'group_set')

如果您真的想坚持使用 group （顺便说一句，这对于列表来说是一个非常糟糕的名字组）。您可以使用 prefetch_related 修改它，如下所示：

If you really want to stick with group (btw this is a very bad name for a list of groups). You can hack it with prefetch_related like so:

queryset = Plan.objects.prefetch_related('group_set', to_attr='group')

这样每 plan 项目将具有 group 属性-一个 queryset 包含以下所有组的属性此计划。

this way every plan item will have a group attribute - a queryset containing all the groups for this plan.

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