不可散列类型：'OrderedDict'

Question

当我尝试在 Postman 中执行 PUT 请求时，我在 Django 中遇到问题。

我怀疑问题是因为我的模型中嵌套了序列化器 class，但我不确定。

class Foo(models.Model):
    foo_name = models.CharField(max_length=50, unique=True)

    foo_statistics = models.ManyToManyField(TrainStatistics)

class FooSerializer(serializers.ModelSerializer):
    blah_statistics = BlahStatisticsSerializer(many=True)

    class Meta:
        model = Foo
        fields = ('foo_statistics')
        depth = 2 

    def create(self, validated_data):
        """
        Create and return a new `Summary` instance, given the validated data.
        """

        blah_statistics_data = validated_data.pop('blah_statistics')
        foo = Foo(**validated_data)

        for blah_statistic in blah_statistics_data:
            FooStatistic.objects.create(summary=summary, **train_statistic)
        return summary

    def update(self, instance, validated_data):
        """
        Update and return an existing `Foo` instance, given the validated data.
        """
        instance.blah_statistics = validated_data.get('blah_statistics', instance.blah_statistics) # This line is causing problems

知道是什么导致了这个问题吗？

Answer 1

问题是经过验证的数据将 train_statistics 变成 OrderedDict（使用嵌套序列化程序总是有点棘手），所以 OrderedDicts 是不可散列的，所以当你尝试到 ".get" 它会引发错误。

一个选项是将您的字段 train_statistics 设置为只读。

然后在您的 update() 方法中，不要使用 validated_data 来获取 train_statistics，而是使用 request.data 来获取它们。对 create() 方法执行相同的操作。

class SummarySerializer(serializers.ModelSerializer):
    train_statistics = TrainStatisticsSerializer(many=True, read_only=True)

    class Meta:
        model = Summary
        fields = ('train_statistics')
        depth = 2 

    def create(self, validated_data):
        """
        Create and return a new `Summary` instance, given the validated data.
        """
        request = self.context['request']
        train_statistics_data = request.data.get('train_statistics')
        summary = Summary.objects.create(**validated_data)

        for train_statistic in train_statistics_data:
            TrainStatistics.objects.create(summary=summary, **train_statistic)
        return summary

    def update(self, instance, validated_data):
        """
        Update and return an existing `Summary` instance, given the validated data.
        """
        request = self.context['request']
        instance.train_statistics =request.data.get('train_statistics', instance.train_statistics) # This line is causing problems

调用序列化程序时，需要将请求对象作为上下文数据传递。

SummarySerializer(instance, data=data, context={'request':request})

或

SummarySerializer(data=data, context={'request':request})

不可散列类型：'OrderedDict'

unhashable type: 'OrderedDict'

django

django-rest-framework

ordereddictionary