Understanding Odoo Model Relationships: A Quick Guide

Odoo is an open-source ERP (Enterprise Resource Planning) platform with a powerful ORM (Object-Relational Mapping) layer that facilitates the creation and management of various data models. In Odoo models represent tables in a database, and these models can have relationships with one another. Understanding these relationships is crucial for designing an efficient data structure and implementing business logic.

Types of Relationships in Odoo

Odoo provides several types of relationships between models:

1. Many-to-One (many2one):

• This is the most common type of relationship in Odoo. It represents a many-to-one relationship, meaning many records of one model can be related to a single record of another model.
• For example, in a model representing employees (hr.employee), there could be a many2one field to a department model (hr.department), indicating that each employee belongs to one department.
• Field Definition:
  python department_id = fields.Many2one('hr.department', string='Department')

2. One-to-Many (one2many):

• This relationship is the inverse of a many2one relationship. It represents that one record of a model is linked to many records of another model.
• Continuing the example above, a department can have multiple employees, so in the hr.department model, there would be a one2many field for employees.
• Field Definition:
  python employee_ids = fields.One2many('hr.employee', 'department_id', string='Employees')
• Here, 'hr.employee' is the related model, and 'department_id' is the field defined in the hr.employee model that creates the link.

3. Many-to-Many (many2many):

• This relationship represents a many-to-many association, where records from two models can be associated with each other in a bi-directional relationship.
• For example, consider a scenario where projects can have multiple employees, and employees can work on multiple projects. This can be implemented using a many2many field.
• Field Definition:
  python project_ids = fields.Many2many('project.project', string='Projects')
• The Many2many field automatically creates a third table in the database that stores the associations between records.

Usage and Practical Example

Let’s consider a simple example of creating models for a Library Management System in Odoo.

• Model 1: Book (library.book)

  class LibraryBook(models.Model):
      _name = 'library.book'
      _description = 'Book Record'

      name = fields.Char(string='Title', required=True)
      author_ids = fields.Many2many('library.author', string='Authors')

• Model 2: Author (library.author)

  class LibraryAuthor(models.Model):
      _name = 'library.author'
      _description = 'Author Record'

      name = fields.Char(string='Name', required=True)
      book_ids = fields.Many2many('library.book', string='Books')

In this example:

• The library.book model has a many2many relationship with the library.author model and vice versa.
• Each book can have multiple authors, and each author can write multiple books.

Conclusion

Odoo is basically an open-source ERP platform with a robust ORM (object-relational mapping) layer that enables the formation and management of different data models. Odoo models mainly show tables in the database, and all these models can simply have relationships with each other by having managed Odoo server solutions. Knowing these relationships is very important for creating a resourceful data structure and applying good business logic.