marshmallow-jsonapi forcing loading of related data

I’m using marshmallow-jsonapi with sqlalchemy, and it’s forcing loading of related data, when all I want is for marshmallow-json to create a link to related data. Here’s a snippet of what I’m doing:

class Server(db.Model):
    __tablename__ = 'servers'

    id = db.Column(db.Integer,
                   primary_key=True)
    hostname = db.Column(db.String(255, collation='utf8_bin'),
                         unique=True,
                         nullable=False)

    jobs = db.relationship('Job', back_populates='server')


class Job(db.Model):
    __tablename__ = 'jobs'

    id = db.Column(db.Integer,
                   primary_key=True)
    server_id = db.Column(db.Integer, db.ForeignKey('servers.id'),
                          nullable=False)
    name = db.Column(db.String(255, collation='utf8_bin'),
                     index=True,
                     nullable=False)

    server = db.relationship('Server', back_populates='jobs')


class JobSchema(Schema):
    id = fields.Integer(dump_only=True)
    name = fields.String()

    server = Relationship(
        related_view='.server_detail',
        related_view_kwargs={'server_id': '<server_id>'},
        include_data=False,
    )

    class Meta:
        type_ = 'jobs'

data = JobSchema().dump(Job.query.all(), many=True).data

Rendering these jobs triggers an access to a job’s server field, which triggers a SQL query to fetch the server, even though the fetched server record is never used. It would be great if marshmallow-jsonapi was able to suppress marshmallow accessing this field.

As a workaround, I can cheat the relationship, and just add a attribute="id" to the Relationship constructor, which I know will always be present on the record. It’s not ideal, but it works.

[danpoland]

The related PR: https://github.com/marshmallow-code/marshmallow-jsonapi/pull/82

[danpoland]

You still might run into an issue where you want to allow includes to follow the relationship when there is a include=my_relation query string in the request but the rest of the time you just want to use the foreign key. I have a solution for this problem that I will eventually PR.