难以置信的类型：'OrderedDict'

Question

我在Django遇到一个问题，当我尝试在Postman中执行PUT请求时。

我怀疑这个问题是因为我在模型类中嵌套了序列化器，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 

任何想法可能会导致此问题？

Answer 1

的问题是，经过验证的数据变成train_statistics为OrderedDict（始终是有点棘手嵌套串行工作），所以OrderedDicts是unhashable，所以当你尝试“.get”它会引发错误。

一个选项是将字段train_statistics设置为只读。

然后在您的update()方法中，而不是使用validated_data来获得train_statistics，请使用request.data来获取它们。对create()方法做同样的操作。

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 

当您调用序列化程序时，需要传递请求对象作为上下文数据。

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

或

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