不可散列的类型：'OrderedDict'

Question

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

我怀疑这个问题是因为我的模型类中有嵌套的序列化程序，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 转换为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“.get”时它会引发一个错误。

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 获取train_statistics，而是使用request.data 获取它们。对create() 方法执行相同操作。

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

当您调用序列化程序时，您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})