data_key parameter not working

As I understand the docs, I could use the data_key param if the name of the field is not the same as the key name in the dict.

data_key (str) – The name of the key to get the value from when deserializing. If None, assumes the key has the same name as the field.

However, this does not work for me. The your_name field is not loaded from the dict. If I change the key to name it gets loaded and the data objects now has a key your_name. That is not what I expected based on the documentation. I am using marshmallow==2.19.2.

>>> from marshmallow import Schema, fields
>>> class FooLoad(Schema):
...     name = fields.Str(data_key='your_name')
... 
>>> schema_load = FooLoad()
>>> schema_load.load({'your_name': 'qwertz'})
UnmarshalResult(data={}, errors={})
>>> schema_load.load({'name': 'qwertz'})
UnmarshalResult(data={'your_name': 'qwertz'}, errors={})

[lafrech]

Both attribute and data_key are used for both serialization and deserialization. They are just at the opposite end of the chain.

Object ------------- Field ------------- Serialized dict attribute ------------------------------- data_key (or field name) -------------------- (or field name)

[kristian-lindin]

Thanks for such nice and fast replies 😃!