SQLAlchemy filter all relationships - flask

Question

so I have these four tables
class ClimbingHallSectionModel(BaseModel):
__tablename__ = 'climbing_hall_section'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(50), nullable=False)
climbing_hall_id = db.Column(db.Integer, db.ForeignKey('climbing_hall.id', ondelete='CASCADE'), nullable=False)
walls = db.relationship('ClimbingWallModel', lazy='select', passive_deletes=True)
class ClimbingWallModel(BaseModel):
__tablename__ = 'climbing_wall'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(50), nullable=False)
climbing_hall_section_id = db.Column(db.Integer, db.ForeignKey('climbing_hall_section.id', ondelete='CASCADE'), nullable=False)
height = db.Column(db.Integer)
lines = db.relationship('LineModel', lazy='select', passive_deletes=True)
class LineModel(BaseModel):
__tablename__ = 'line'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(50), nullable=False)
climbing_wall_id = db.Column(db.Integer, db.ForeignKey('climbing_wall.id', ondelete='CASCADE'), nullable=False)
routes = db.relationship('RouteModel', lazy='select', passive_deletes=True)
class RouteModel(BaseModel):
__tablename__ = 'route'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(100), nullable=False)
active = db.Column(db.Boolean, nullable=False, default=True)
line_id = db.Column(db.Integer, db.ForeignKey('line.id', ondelete='CASCADE'), nullable=False)
I want to query all sections where the attribute active of the route table is true.
I tried the following query:
sections = (db.session.query(ClimbingHallSectionModel)
.join(ClimbingWallModel)
.join(LineModel)
.join(RouteModel)
.filter(RouteModel.active==True).all())
This query returns indeed only these sections which contains routes with the attribute active set to true.
However if I now acces the routes of one of the sections with sections.walls[0].lines[0].routes, I get all routes of the selected line including the routes where active is set to false.
For me it looks like that the filter only works correctly on the ClimbingHallSection level but then is not passed to the related tables.
Of course I could do something like this
sections = (db.session.query(ClimbingHallSectionModel, ClimbingWallModel, LineModel, RouteModel)
.select_from(ClimbingHallSectionModel)
.join(ClimbingWallModel)
.join(LineModel)
.join(RouteModel)
.filter(RouteModel.active==True).all())
But this would return a list of tubles:
sections = [
(<ClimbingHallSectionMode 1>, <ClimbingWallModel 1>, <LineModel 1>, <RouteModel 1>),
(<ClimbingHallSectionMode 1>, <ClimbingWallModel >, <LineModel 1>, <RouteModel 2>),...]
I don't know if this is even possible but how can I "pass" the filter arguments to all related tables so that the a section would only contain theses wall which containing lines which contain only routes with active set to true?

Answer 1

Here's a (currently partial) demonstration of the joinedload option.
Change your RouteModel model so that relationships adorn the parent table:
class ClimbingHallSectionModel(BaseModel):
__tablename__ = 'climbing_hall_section'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(50), nullable=False)
climbing_hall_id = db.Column(db.Integer, db.ForeignKey('climbing_hall.id', ondelete='CASCADE'), nullable=False)
walls = db.relationship('ClimbingWallModel', lazy='select', passive_deletes=True)
class ClimbingWallModel(BaseModel):
__tablename__ = 'climbing_wall'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(50), nullable=False)
climbing_hall_section_id = db.Column(db.Integer, db.ForeignKey('climbing_hall_section.id', ondelete='CASCADE'), nullable=False)
height = db.Column(db.Integer)
lines = db.relationship('LineModel', lazy='select', passive_deletes=True)
class LineModel(BaseModel):
__tablename__ = 'line'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(50), nullable=False)
climbing_wall_id = db.Column(db.Integer, db.ForeignKey('climbing_wall.id', ondelete='CASCADE'), nullable=False)
routes = db.relationship('RouteModel', lazy='select', passive_deletes=True)
class RouteModel(BaseModel):
__tablename__ = 'route'
id = db.Column(db.Integer, primary_key=True, autoincrement=True)
name = db.Column(db.String(100), nullable=False)
active = db.Column(db.Boolean, nullable=False, default=True)
line_id = db.Column(db.Integer, db.ForeignKey('line.id', ondelete='CASCADE'), nullable=False)
rev_routes = db.relationship('LineModel', back_populates='routes')
Then, this query ought to give you the related table rows you need, at least for LineModel table:
sections = (db.session.query(RouteModel)
.options(joinedload(RouteModel.rev_routes))
.filter(RouteModel.active==True).all())
For each section in sections, iterate section.rev_routes to access filtered rows in that related table. The joinedload concept does not work (AFAIK) in a sequence of chained relationships, but this may be a start.