python - 将 PrimaryKeyRelatedField 替换为另一个字段

Question

我的模型由 User 模型和 Present 模型组成。一个User可以有多个Present，但一个Present有一个唯一的User:

我的models.py是:

from django.db import models
from django.contrib.auth.models import User

class Present(models.Model):
    name = models.CharField(max_length=15)
    price = models.FloatField()
    link = models.CharField(max_length=15)
    isAlreadyBought = models.BooleanField()
    user = models.ForeignKey(User, related_name='presents', on_delete=models.CASCADE)

我的serializers.py是:

from django.contrib.auth.models import User, Group
from rest_framework import serializers
from blog.models import Present, Location
from django.contrib.auth.models import User


class UserSerializer(serializers.ModelSerializer):

    presents = serializers.PrimaryKeyRelatedField(many=True, queryset=Present.objects.all(), required=False)

    class Meta:
        model = User
        fields = ('username', 'password', 'email', 'presents')

    def create(self, validated_data):
        user = super().create(validated_data)
        if 'password' in validated_data:
                user.set_password(validated_data['password'])
                user.save()
        return user



class PresentSerializer(serializers.ModelSerializer):

    user = serializers.PrimaryKeyRelatedField(queryset=User.objects.all(), read_only=False, many=False)

    class Meta:
        model = Present
        fields = ('name', 'link', 'price', 'isAlreadyBought', 'user')

    def create(self, validated_data):
        return Present.objects.create(**validated_data)

目前，如果我想获取与给定用户关联的所有礼物，我使用主键(在 views.py 中):

class PresentsOfUser(viewsets.ModelViewSet):
    queryset = Present.objects.all().filter(user=33)
    serializer_class = PresentSerializer

但是，我宁愿使用 User 的 username 字段而不是主键。

我尝试过使用 SlugRelatedField 但我不确定这是实现我的目标的正确方法:

class PresentSerializer(serializers.ModelSerializer):

    user = serializers.SlugRelatedField(queryset=User.objects.all(), slug_field='username', read_only=False, many=False)

    class Meta:
        model = Present
        fields = ('name', 'link', 'price', 'isAlreadyBought', 'user')

    def create(self, validated_data):
        return Present.objects.create(**validated_data)

经过此修改，我现在使用以下 View 来获取 id 为 33< 的用户 'Marcel'/:

class PresentsOfUser(viewsets.ModelViewSet):
    queryset = Present.objects.all().filter(user='Marcel')
    serializer_class = PresentSerializer

但在这种情况下，我得到:

ValueError: invalid literal for int() with base 10: 'Marcel'

但是，如果我将 user='Marcel' 替换为 user=33(如前所述)，我会得到:

[{"name":"Nintendo","link":"fake_link","price":50.8,"isAlreadyBought":true,"user":"Marcel"},{"name":"Gamecube","link":"fake_link","price":50.8,"isAlreadyBought":true,"user":"Marcel"}]

其中用户字段现在是用户名，而不是用户的id。

但是，我不明白为什么使用 user='Marcel' 过滤失败...

Answer 1

我最终覆盖了 get_queryset 方法，同时将 PrimaryKeyRelatedField 保留在我的序列化程序中(使用 user__username='Marcel' 作为 mishbah 的建议) :

class PresentsOfUser(viewsets.ModelViewSet):

    serializer_class = PresentSerializer

    def get_queryset(self):
        """
        Optionally restricts the returned purchases to a given user,
        by filtering against a `username` query parameter in the URL.
        """
        queryset = Present.objects.all()
        username = self.kwargs['user']
        if username is not None:
            queryset = queryset.filter(user__username=username)

        if len(queryset) == 0:
            raise Http404

        return queryset

当用 SlugRelatedField 替换 PrimaryKeyRelatedField 时，它也适用:

user = serializers.SlugRelatedField(queryset=User.objects.all(), slug_field='username', read_only=False, many=False)

并在我的 Present 模型的 ForeignKey 中添加 to_field='username':

user = models.ForeignKey(User, related_name='presents', to_field='username', on_delete=models.CASCADE)