Django Rest Framework序列化程序更新方法不保存对象 [英] Django Rest Framework serializer update method does not save object

问题描述

在保存对象之前，我已经覆盖了我的一个序列化器的update方法，以调用模型的方法。像这样：

I have overridden the update method for one of my serializers to call a model's method before saving the object. Like so:

class MyModelSerializer(serializers.ModelSerializer):
    class Meta:
        model = MyModel
        fields = [...]

    def update(self, instance, validated_data):
        instance.model_method()
        instance.save()
        return instance

在我看来，我正在使用 serializer.save保存序列化程序。 （），当然也可以使用 MyModelSerializer（instance，data = request.data）进行设置。但是，我的实例未保存。仅删除update方法可以保存实例，但显然不会调用 model_method（）。如何解决此问题？谢谢您的帮助。

In my views, I am saving the serializer using serializer.save(), and of course setting it using MyModelSerializer(instance, data=request.data). However, my instance is not being saved. Just removing the update method saves the instance, but does not call the model_method() obviously. How can I fix this issue? Thanks for any help.

推荐答案

您需要调用 super（）调用 instance.model_method（）之后的方法，以便将数据保存在更新的实例上。

You need to call super() method after instance.model_method() is called so as to save the data on the updated instance.

上面提到的方法的问题是 validated_data 未被用于 save（）保留实例不变。

The problem with the approach mentioned above in the question is that validated_data is not used anywhere to save() which leaves the instance as is.

class MyModelSerializer(serializers.ModelSerializer):
    class Meta:
        model = MyModel
        fields = [...]

    def update(self, instance, validated_data):
        instance.model_method() # call model method for instance level computation

        # call super to now save modified instance along with the validated data
        return super().update(instance, validated_data)  

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