Adding relational fields to a model

Relational fields are used to represent relations between Odoo models. There are three types of relations:

• many-to-one, or m2o for
• one-to-many, or o2m for short
• many-to-many, or m2m for short

To illustrate this, let’s consider the hostel room model. A room belongs to a single hostel, so the relation between the hostel and the room is m2o. However, a hostel can have multiple rooms, so the opposite relationship is o2m.

We can also have a m2m relationship. For instance, a room can offer various amenities and amenities can be available in different rooms. This is a bidirectional m2m relationship.

Getting ready

We will continue using the my_hostel add-on module from the previous recipe.

How to do it...

We will edit the models/hostel_room.py file to add these fields:

1. Add the m2o field for the hostel in Hostel Room:

   class HostelRoom(models.Model):
       
   # ...
       ...