下面是我在基于 SQLAlchemy 的应用程序中使用的 python棉花糖序列化程序。
import simplejson
from marshmallow import Schema
class MySerializer(Schema):
class Meta:
json_module = simplejson
fields = ('field1', 'field2', 'field3')
field3 = fields.Method('get_field3')
def get_field3(self, this_obj):
return "Hello"
这是我如何称呼这个序列化程序:
my_argument = 1
items=MySerializer(documents=list_of_my_objects, many=True).data
现在,我想更改序列化程序,使其接受一个附加参数(我将传入my_argument
),如果该参数的值为 1,则返回"Goodbye"
代替"Hello"
. 我怎样才能做到这一点?
特别是,我不知道如何将参数传递给这个 marshamallow Schema,以便它可以从 inside 中获得get_field3
。我知道我需要重写该__init__()
方法。但我不确定它应该是什么样子。我尝试了以下方法,但没有奏效:
def __init__(self, documents, many, my_arg):
self.my_arg = my_arg
super(Schema, self).__init__(documents, many=many)
def get_field3(self, this_obj):
self.my_arg == 1:
return "Goodbye"
else:
return "Hello"
这是我得到的堆栈跟踪:
my_project/my_models/serializers.pyc in __init__(self, documents, many, my_arg)
---> 25 super(Schema, self).__init__(documents, many=many)
my_virtualenv/lib/python2.7/site-packages/marshmallow/schema.pyc in __init__(self, obj, extra, only, exclude, prefix, strict, many, skip_missing, context)
--> 273 self._update_fields(self.obj, many=many)
my_virtualenv/lib/python2.7/site-packages/marshmallow/schema.pyc in _update_fields(self, obj, many)
--> 636 ret = self.__filter_fields(field_names, obj, many=many)
my_virtualenv/lib/python2.7/site-packages/marshmallow/schema.pyc in __filter_fields(self, field_names, obj, many)
--> 683 attribute_type = type(obj_dict[key])
TypeError: list indices must be integers, not str