marshmallow_test.py

# Requires Marshmallow version 3 in order to raise exceptions from
# loading
# pip install marshmallow --pre
from marshmallow import fields, Schema, post_load, validates, ValidationError


class Location():
    def __init__(self, latitude: float, longitude: float) -> None:
        self.latitude = latitude
        self.longitude = longitude


class ParkingLot():
    def __init__(self, capacity: int, name: str, price: float, location: Location) -> None:
        self.capacity = capacity
        self.name = name
        self.price = price
        self.location = location
        self.id = None


class LocationSchema(Schema):
    latitude = fields.Float(required=True)
    longitude = fields.Float(required=True)


class ParkingLotSchema(Schema):
    capacity = fields.Int(required=True)
    name = fields.Str(required=True)
    price = fields.Float()
    location = fields.Nested(LocationSchema, required=True)

    @validates('price')
    def validate_price(self, price: float):
        if price < 0:
            raise ValidationError("Price must be non-negative")

    @validates('capacity')
    def validate_capacity(self, capacity: int):
        if capacity < 1:
            raise ValidationError("Capacity must be positive")

    @post_load
    def build_parking_lot(self, data: dict) -> ParkingLot:
        return ParkingLot(**data)


if __name__ == '__main__':
    schema = ParkingLotSchema()
    correct_data = {'location': {'latitude': 1.0, 'longitude': 2.0},
                    'name': 'my_parking_lot', 'capacity': 500, 'price': 1.5}
    invalid_data = {'location': {'latitude': 1.0, 'longitude': 2.0},
                    'name': 'my_parking_lot', 'capacity': -999, 'price': 1.5}
    missing_data = {'location': {'latitude': 1.0, 'longitude': 2.0},
                    'name': 'my_parking_lot', 'price': 1.5}
    missing_loc_data = {'location': {'longitude': 2.0},
                        'name': 'my_parking_lot', 'capacity': 500, 'price': 1.5}

    for data in (correct_data, invalid_data, missing_data, missing_loc_data):
        try:
            pl = schema.load(data)
            print(pl)
        except ValidationError as err:
            print(err)