Flask Many to Many relations get values - flask

Question

I want to use many to many relationship in this scenario. I am trying make a compatible table. I don't know if this approch is okay or not. I can add data in os, python and ml table but not in associations table. How can I do it?? I want to add data in associations table and get data by query or anything from associations table.
Associations= db.Table('Associations',
db.Column('FKID_OS', db.Integer, db.ForeignKey('os.id'), primary_key=True),
db.Column('FKID_MLFRAMEWORK', db.Integer, db.ForeignKey('mlframework.id'), primary_key=True),
db.Column('FKID_PYTHON', db.Integer, db.ForeignKey('python.id'), primary_key=True)
)
class OS(db.Model):
__tablename__ = "os"
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(64))
def save(self):
db.session.add(self)
db.session.commit()
def delete(self):
db.session.delete(self)
db.session.commit()
def update(self, data):
for key, val in data.items():
setattr(self, key, val)
db.session.commit()
def __repr__(self):
return f"<OS {self.id}>"
class MLFramework(db.Model):
__tablename__ = "mlframework"
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(64))
def save(self):
db.session.add(self)
db.session.commit()
def delete(self):
db.session.delete(self)
db.session.commit()
def update(self, data):
for key, val in data.items():
setattr(self, key, val)
db.session.commit()
def __repr__(self):
return f"<MLFramework {self.id}>"
class Python(db.Model):
__tablename__ = "python"
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(64))
def save(self):
db.session.add(self)
db.session.commit()
def delete(self):
db.session.delete(self)
db.session.commit()
def update(self, data):
for key, val in data.items():
setattr(self, key, val)
db.session.commit()
def __repr__(self):
return f"<Python {self.id}>"