Support for serializing return values of methods that have default arguments.

[HamishWHC]

I have a method on my Post model that allows me to check if a user has liked it. If not given a user, it will default to the current user from the Flask request context. Given that no argument is needed to call the function, it would be nice to serialize the output.

[HamishWHC]

Alternatively, the ability to rename the serialized fields would be helpful, as I could make a method that is compatible and rename the serialized form to the same name.

[n0nSmoker]

SerializerMixin already supports serializing non‑SQLAlchemy attributes and zero‑arg methods when you list them in rules / serialize_rules / only.

You can add the method into the schema in two main ways.

Per-call:

post_dict = post.to_dict(rules=('is_liked',))
# or, if you also want SQLA fields:
# post_dict = post.to_dict(rules=('is_liked',))

Globally for the model:

class Post(db.Model, SerializerMixin):
    # include all usual fields + computed one
    serialize_rules = ('is_liked',)
    # or, if you want strict control:
    # serialize_only = ('id', 'title', 'body', 'is_liked')

    # columns...
    id = db.Column(db.Integer, primary_key=True)
    # ...

Result:

post.to_dict()
# -> { 'id': 1, 'title': '...', 'body': '...', 'is_liked': True }

Let me know if this does not work for you

[HamishWHC]

Yes but if the method has kwargs that do not require values (i.e. they have default values set), the serializer can't use it.

[n0nSmoker]

Please give an example code to elaborate a solution.

[n0nSmoker]

BTW you can contribute a PR with a test that checks your particular case and fails. So I can adjust the lib and propose a solution.

[n0nSmoker]

@HamishWHC please checkout this PR
Is that what you were talking about?

[HamishWHC]

Sorry for the lack of response, my work doesn't use GH so I don't check GH notifications very regularly.

That PR seems to address my issue perfectly! Thanks!