Pass Request To Different Class Based On Condition Python

I am designing an API which deals with different type of vehicles for example cars, buses and vans. There is an endpoint POST /vehicle which will take a defined body. { 'registrat

Solution 1:

The way it looks to me, you can improve design a bit. Since each vehicle 'knows' where it is serviced, you should probably do in each something like

def __init__(self, ..., service):
    super().__init__(self, ...)
    ...
    ...
    service.register_vehicle(self)

this is coming from the perspective that "the car drives to the garage to register" rather than the "garage looks for new cars".

When you initialize a vehicle, pass it its servicing class, as in

new_car = Car(..., my_car_service)

where

my_car_service = Cars()

somewhere before. This is since we assume each new car needs to register, and we do not make a new service for each new car. Another approach, is for the class to contain (composition) its service object from the get go:

class Car:
    service = Cars()
    def __init__(...)
        ...
        Car.service.register_vehicle(self)

so the class contains the servicing object always, and all initialized objects share the same one through a class variable. I actually prefer this.

---

First initialization:

With regard to your initial initialization of the vehicle, while using locals might be a nifty solution for that, it might be a bit more type safe to have something like what you have. In Python I like to use the "Python switch dictionary" (TM) for stuff like that:

{'car': Car,
 'bus': Bus,
  ...
 'jet': Jet
}[body[vehicle_type]](body)

Solution 2:

I don't know if using locals would be ideal, but at least I believe it would scale better than your current solution:

• use string name to instantiate classes from built-in locals() which will store imports as a dictionary

class Car(object):
    def print(self):
        print("I'm a car")
class Bus(object):
    def print(self):
        print("I'm a bus")

vehicle_type = "Car"
currV_class = locals()[vehicle_type]
currV_instance = currV_class()
#currV_instance.register_vehicle
currV_instance.print()

vehicle_type = "Bus"
currV_class = locals()[vehicle_type]
currV_instance = currV_class()
#currV_instance.register_vehicle
currV_instance.print()

OUTPUT:

I'm a car
I'm a bus