python - SQLAlchemy: one to "fixed number" relationship -

lets have basic table setup this:

class car(base):     __tablename__ = 'cars'     car_id = column(integer, primary_key=true)     someotherinfo = column(string)  class tire(base):     __tablename__ = 'tires'     tire_id = column(integer, primary_key=true)     car_id = column(integer, foreignkey('car.car_id'))     someotherinfo = column(string) 

i want relationship between car , tire, such each car has 4 tires associated it. this, add car definition:

tire1 = relationship("tire", uselist=false, backref="car") tire2 = relationship("tire", uselist=false, backref="car") tire3 = relationship("tire", uselist=false, backref="car") tire4 = relationship("tire", uselist=false, backref="car") 

but wouldn't allow me iterate on tires (in real problem there more 4 tires). else be:

tires = relationship('tire', backref='car') 

but doesn't restrict tires maximum of 4, , doesn't allow me access specific tire (i guess tires list not ordered). want this:

tires = relationship('tire', backref='car', max=4, usearray=true) 

where can address tire (array sorted), restrict 4, , able iterate on them.

this first question, hope clear , please correct me if did wrong.

thanks lot!

i solve problem associative table.

class tirecar(base):     __tablename__ = 'tire_car_assoc'     tire_id = column(integer, primary_key=true)     car_id = column(integer, primary_key=true)     order = column(integer)     someotherinfo = column(string) 

where define tire_id , car_id foreignkey of course.

this way can iterate relation or whatever need need do. if can have 4 relations (or n in real problem) between 2 tables, control in python.

(the way reason slqalchemy, or orm matter, not different database. i'd say, then, design solution mind in database, , implement orm. maybe don't particularly solution, incomplete, besides have information of functional model! hope helps find own solution.)