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Deserialization of Hyperlinks and URL fields fails #9

sloria opened this issue Dec 22, 2014 · 2 comments


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commented Dec 22, 2014

From @raj-kesavan in #7 :

Simple set up with Flask-RESTful and Flask-Marshmallow. When I navigate to /api/v1/person, I get a 500 Internal Server Error. Server logs at bottom.

class PersonSchema(ma.Schema):
    name = ma.String(required = True)
    friends = ma.Hyperlinks({
        'href': ma.AbsoluteURL('person_ep')

class PersonAPI(Resource):
    def get(self):
        person, errors = PersonSchema().load({
            'name': 'Rob'

api.add_resource(PersonAPI, '/api/v1/person/', endpoint = 'person_ep')

Server log

[Mon Dec 22 04:15:16 2014] [error] [client]   File "/usr/local/lib/python2.7/dist-packages/flask_restful/", line 521, in dispatch_request
[Mon Dec 22 04:15:16 2014] [error] [client]     resp = meth(*args, **kwargs)
[Mon Dec 22 04:15:16 2014] [error] [client]   File "/var/www/html/devabacus/abacus/", line 95, in get
[Mon Dec 22 04:15:16 2014] [error] [client]     'name': 'Rob'
[Mon Dec 22 04:15:16 2014] [error] [client]   File "/usr/local/lib/python2.7/dist-packages/marshmallow/", line 498, in load
[Mon Dec 22 04:15:16 2014] [error] [client]     dict_class=self.dict_class
[Mon Dec 22 04:15:16 2014] [error] [client]   File "/usr/local/lib/python2.7/dist-packages/marshmallow/", line 260, in deserialize
[Mon Dec 22 04:15:16 2014] [error] [client]     key = fields_dict[attr_name].attribute or attr_name
[Mon Dec 22 04:15:16 2014] [error] [client] AttributeError: 'Hyperlinks' object has no attribute 'attribute'

@sloria sloria added the bug label Dec 22, 2014

@sloria sloria closed this in d7f6256 Dec 22, 2014


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commented Dec 22, 2014

Thank you, this works great.

Maybe this will be helpful for someone else:
I was having a problem because my URLs included the id attribute, but this wasn't supplied by the user when submitting a PUT request. Since PUT is idempotent, I needed to deserialize and then serialize the data (providing empty strings for optional attributes); it broke upon serializing because the generated user had no id attribute (necessary for the link). I made a new class, LinkedUserSchema which inherited from UserSchema and moved the links to the LinkedUserSchema instead - then my deserializing/serializing was done with UserSchema, which had all the data it needed to validate, then my GET request would use the LinkedUserSchema.

Thanks again.


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commented Dec 23, 2014

Thanks @raj-kesavan for the suggestion.

If marshmallow-code/marshmallow#61 gets implemented, you would be able to add the read_only flag to the link-related fields, so that they are only active for serialization (but not validation/deserialization). In the meantime, I think your solution is fine.

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