django - 我如何在序列化器中计算？

Question

这是我的序列化器:
序列化器

start_at=serializers.DateTimeField(format="%Y-%m-%d %H:%M:%S")
end_at = serializers.DateTimeField(format="%Y-%m-%d %H:%M:%S")  

现在我想在序列化器中进行计算，使这个end_at - start_at
并将该值赋予 waite_time
我该怎么做？

Answer 1

您可以使用 SerializerMethodField 对于此事:

This is a read-only field. It gets its value by calling a method on the serializer class it is attached to. It can be used to add any sort of data to the serialized representation of your object.

您没有提供类(class)的任何详细信息，但这可能是这样的:

class MySerializer(serializers.ModelSerializer):
    start_at = serializers.DateTimeField(format="%Y-%m-%d %H:%M:%S")
    end_at = serializers.DateTimeField(format="%Y-%m-%d %H:%M:%S")
    # .... (any fields)
    diff = serializers.SerializerMethodField()

    def get_diff(self, obj):
        return obj.end_at - obj.start_at

    # .... (any meta etc)

您还可以在 SerializerMethodField 中指定自定义方法名称否则默认为 get_<field_name> .