Hello, I'm new to python... Now I'm just learning how to make a simple Odoo module...

Here's the model:

route.py

from openerp import models, fields
class CourierRoute(models.Model):
    _name = 'courier.route'

    name = fields.Char(string="Route", help="Format: Origin City > Destination City", required=True)
    origin = fields.Many2one('courier.city', string="Origin City", required=True)
    destination = fields.Many2one('courier.city', string="Destination City", required=True)
    train = fields.Many2one('courier.train', string="Train", required=False)
    cost_price = fields.Integer(string="Cost Price", required=False)
    origin_price = fields.Integer(string="Origin City Shipment Price", readonly=True)
    destination_price = fields.Integer(string="Destination City Shipment Price", readonly=True)
    train_price = fields.Integer(string="Train Shipment Price", readonly=True)

city.py

from openerp import models, fields
class CourierCity(models.Model):
    _name = 'courier.city'

    name = fields.Char(string="City", required=True)
    price = fields.Integer(string="Shipping Price", required=True)

train.py

from openerp import models, fields
class CourierTrain(models.Model):
    _name = 'courier.train'

    name = fields.Char(string="Train", help="Format: Origin Station > Destination Station", required=True)
    price = fields.Integer(string="Shipping Price", required=True)

So I was creating a model for choosing necessary shipping route, and then compute all of the prices/cost that have been filled (some are not). But every time I want to make a def, I was confused by the cr,uid,and that such of things, I can't understand it.

Any help or advice is appreciated.