从 SQLAlchemy class 到 Z9784E91C7B2657917226BC82ZAFDD6 中的 JSON 返回混合属性

Question

looking for some help on the following.

I am using flask_sqlalchemy on Python 3+. I have a simple User and a Training class; definitions below. I have a hybrid property on the Training class that will return a boolean indicating whether the user is subscribed to the training or not. This works like a charm when working with the Jinja template engine, as I can use "training.is_subscribed(current_user)".

{% if training.is_subscribed(current_user) %}
<button type="button" class="btn btn-outline-success" disabled>Subscribed</button> You can no longer join
{% else %} 

However, now I'm writing a API route as well and returning JSON. I'm using a simple Schema (marshmallow_sqlalchemy) to serialize the Training instance. However, when trying to add "is subscribed" I run into the error indicating that I did not pass a user. Which is true, but I'm not sure how to do that. Can you please help?

TypeError: is_subscribed() missing 1 required positional argument: 'user'

Thanks! Scott

Definitions

training_subscribers = db.Table('training_subscribers',
    db.Column('subscriber_id', db.Integer(), db.ForeignKey('user.id')),
    db.Column('training_id', db.Integer(), db.ForeignKey('training.id')))

class User(db.Model, UserMixin):

    id = db.Column(db.Integer, primary_key=True)
    email = db.Column(db.String(255), unique=True)

    trainings = db.relationship('Training', secondary=training_subscribers,
                        backref=db.backref('subscribers', lazy='dynamic'))  

class Training(db.Model):

    id = db.Column(db.Integer, primary_key=True)
    title = db.Column(db.String(250), nullable=False)

    @hybrid_property
    def is_subscribed(self, user) -> bool:
        return self.subscribers.filter(
            training_subscribers.c.subscriber_id == user.id).count() > 0

class TrainingSchema(SQLAlchemySchema):
    class Meta:
        model = Training
        fields = ("is_subscribed","title", "id")

Code to get the JSON response

@mod_trainings.route('/json/bydate/<int:year>/<int:month>/<int:day>', methods=['GET'])
@login_required
def showUpcomingTrainingsJSONByDate(year, month, day):
    trainings = trainingController.getTrainingsAtDate(year, month, day)
    training_schema = TrainingSchema(many=True)
    return jsonify(training_schema.dump(trainings))

def getTrainingsAtDate(year, month, day):
    trainings_q = db.session.query(Training).filter(extract('year', Training.starts_at)==year).filter(extract('month', Training.starts_at)==month).filter(extract('day', Training.starts_at)==day).all()
    return trainings_q

Answer 1

training.is_subscribed is not actually method, but property, so not callable. It's so complicated. How it works, not calling a function but taking a function out. Then what you get when you refer training.is_subscribed is is_subscribed(self, user) itself. Therefore:

TypeError: is_subscribed() missing 1 required positional argument: 'user'

occurred.

Well, what should we do? It's so easy. Filter data until response JSON. Rendering with current_user means must be able to get this from flask.