Load schema with only=str gives empty UnmarshalResult

[erlingbo]

When using a schema with the only attribute set to a string, the load method returns UnmarshalResult without errors nor data.

class MySchema(Schema):
    class Meta:
        fields = ('pk',)

    pk = fields.String()

MySchema(only='pk').load('an_id1234')
MySchema(only='pk').load({'pk': 'an_id1234'})

Both return the same UnmarshalResult
UnmarshalResult(data={}, errors={})

Preferably the first should work, but the second could be used with a pre load method on the schema class.

Is there anything I have done wrong or is this a bug?

[jklapuch]

Change

 only="pk"

with

only=["pk"]

and the second will work. The first will return:

UnmarshalResult(data={}, errors={u'_schema': [u'Invalid input type.']})

[erlingbo]

yes, it will, but then dump will give me a different result, and thus not solve my probem

[jklapuch]

Other then this?

MySchema(only=["pk"]).dump({'pk': u'an_id1234'})
Out: MarshalResult(data={'pk': u'an_id1234'}, errors={})

[erlingbo]

I see that I posted this in the json-api repo. Should have been in the original marshmallow project. Will close this and reopen it in the correct project.

marshmallow-code/marshmallow#307