嵌套关系返回空字典 DRF

Question

我写了以下代码：

class PredictionSerializer(serializers.HyperlinkedModelSerializer):
    class Meta:
        model = Prediction
        fields = ["id", "market"]
        depth = 1

class FixtureSerializer(serializers.HyperlinkedModelSerializer):
    predictions = PredictionSerializer()
    class Meta:
        model = Fixture
        fields = ["sofascore_id", "home", "away", "league", "round", "date", "predictions"]
        depth = 1 

class FixtureViewSet(viewsets.ReadOnlyModelViewSet):
    """
    API endpoint that allows fixture to be viewed or edited.
    """
    serializer_class = FixtureSerializer
    permission_classes = [permissions.IsAuthenticated]
    filter_backends = [django_filters.rest_framework.DjangoFilterBackend]
    filterset_fields = ("home", "away", "sofascore_id", "statistics")

    def get_queryset(self):
        date = self.request.query_params.get('date')       
        queryset = Fixture.objects.all().order_by('-date')

        if(date):
            queryset = Fixture.objects.filter(date__date=date).order_by('date')
        return queryset

对应以下机型：

class Market(models.Model):
    name = models.CharField(max_length=200)

class Fixture(models.Model):
    sofascore_id = models.CharField(max_length=200)

    home = models.ForeignKey(Team, on_delete=models.CASCADE, related_name="home")
    away = models.ForeignKey(Team, on_delete=models.CASCADE, related_name="away")

    league = models.ForeignKey(League, on_delete=models.CASCADE, blank=True)
    round = models.CharField(max_length=200, default=None, blank=True, null=True)
    date = models.DateTimeField()

    statistics = models.ForeignKey(Statistics, on_delete=models.CASCADE, default=None, blank=True, null=True)

    updated_at = models.DateTimeField(auto_now=True)
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return u'{0} - {1}'.format(self.home.name, self.away.name)

class Prediction(models.Model):
    market = models.ForeignKey(Market, on_delete=models.CASCADE, blank=True)
    fixture = models.ForeignKey(to=Fixture, on_delete=models.CASCADE, related_name="predictions", null=True, blank=True)

当我向 /fixtures 发出请求时，“预测”字典始终为空，但是当我使用以下语句运行一些测试代码时：

f = Fixture.objects.get(sofascore_id=match).predictions.all()

我得到以下作为返回值：

<QuerySet [<Prediction: Prediction object (23)>, <Prediction: Prediction object (24)>, <Prediction: Prediction object (25)>, <Prediction: Prediction object (26)>, <Prediction: Prediction object (27)>, <Prediction: Prediction object (28)>]>

这里有什么问题，为什么我无法使用书面代码检索我的预测？

Answer 1

您需要在序列化程序中指定属性many：

class FixtureSerializer(serializers.HyperlinkedModelSerializer):
    predictions = PredictionSerializer(many=True, read_only=True)
    class Meta:
        model = Fixture
        fields = ["sofascore_id", "home", "away", "league", "round", "date", "predictions"]
        depth = 1