调用一次方法即可在Django Rest Framework序列化程序中设置多个字段 [英] Call method once to set multiple fields in Django Rest Framework serializer
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问题描述
如何使用Django Rest Framework序列化程序一次调用同一方法来设置多个字段?这就是我现在要做的,但这显然两次调用了该方法.如何将其限制为只能调用一次?
How can I call the same method one time to set multiple fields with a Django Rest Framework serializer? This is what I do now but this clearly calls the method two times. How can I limit it to only be called once?
class MyModel(models.Model):
def GetTwoValues(self):
foo = []
bar = []
# expensive operation
return foo, bar
class MyModelSerializer(serializers.HyperlinkedModelSerializer):
foo = serializers.SerializerMethodField()
bar = serializers.SerializerMethodField()
def get_foo(self, obj):
foo, _ = obj.GetTwoValues()
return foo
def get_bar(self, obj):
_, bar = obj.GetTwoValues()
return bar
class Meta:
model = MyModel
fields = ('FirstValue', 'SecondValue',)
推荐答案
有一些选择:
1)存储值,以便仅调用一次昂贵的方法.例如:
1) Store the values so that the expensive method is called only once. E.g.:
def _get_two_values(self, obj):
if not hasattr(self, '_two_values'):
self._two_values = obj.GetTwoValues()
return self._two_values
def get_foo(self, obj):
foo, _ = self._get_two_values(obj)
return foo
def get_bar(self, obj):
_, bar = self._get_two_values(obj)
return bar
2)从序列化器中删除两个字段,并在序列化器的to_representation
方法中分配两个值.例如:
2) Remove both fields from the serializer and assign both values in the serializer's to_representation
method. E.g.:
def to_representation(self, obj):
data = super().to_representation(obj)
foo, bar = obj.GetTwoValues()
data['foo'] = foo
data['bar'] = bar
return data
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