I got flask sqlalchemyerror sqlalchemy.exc.InvalidRequestError: Multiple classes found for path

Question

sqlalchemy version = 1.2.7

sqlalchemy.exc.InvalidRequestError: One or more mappers failed to initialize - can't proceed with initialization of other mappers. Triggering mapper: 'Mapper|Image|Image'. Original exception was: Multiple classes found for path "Visualization" in the registry of this declarative base. Please use a fully module-qualified path.

sqlalchemy.exc.InvalidRequestError: Multiple classes found for path "Visualization" in the registry of this declarative base. Please use a fully module-qualified path.

class Visualization(db.Model):
    __table_args__ = {'extend_existing': True}
    id = db.Column(db.Integer, primary_key=True)
    image_id = db.Column(db.Integer, db.ForeignKey('image.id'),
        nullable=False)
    name = db.Column(db.String(255))
    type=db.Column(db.String(255))
    path = db.Column(db.String(255))
    target_layer = db.Column(db.Integer)
    target_class = db.Column(db.Integer)

class Image(db.Model):
    __table_args__ = {'extend_existing': True}
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(80))
    path = db.Column(db.String(80))
    thumbnail = db.Column(db.String(80))
    prediction = db.Column(db.Float)
    label = db.Column(db.String(80))
    class_index = db.Column(db.Integer)
    visualizations = db.relationship('Visualization', backref='image', lazy=True)

@snakecharmerb No, i haven't any extra class named Visualization" — Harendrra
– Harendrra, Commented Apr 2, 2021 at 16:30

swimmer · Accepted Answer · 2022-09-16 15:02:31Z

1

The error is most likely caused by:

visualizations = db.relationship('Visualization', backref='image', lazy=True)

under class Image.

It seems to indicate that there is additional metadata in db.Model that makes Visualization ambiguous.

Assuming your model is defined in database/models/my_model.py, the issue should be solved by changing the relationship to:

visualizations = db.relationship('database.models.my_model.Visualization', backref='image', lazy=True)

Related SO here.

answered Sep 16, 2022 at 15:02

swimmer

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Andrew Clark · Accepted Answer · 2021-04-02 14:43:31Z

0

Try this

visualizations = db.relationship('Visualization', backref=db.backref('image'), lazy=True)

answered Apr 2, 2021 at 14:43

Andrew Clark

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