Odoo 12 Development Essentials - Fourth Edition

SQL model constraints

SQL constraints are added to the database table definition and are enforced directly by PostgreSQL. They are defined using the _sql_constraints class attribute.

It is a list of tuples, and each tuple has the format (name, code, error):

• name is the constraint identifier name
• code is the PostgreSQL syntax for the constraint
• error is the error message to present to users when the constraint is not verified

We will add two SQL constraints to the Book Model. One is a unique constraint ensuring that we don't have repeated books with the same title and publication date; the other is to check that the publication date is not in the future:

# class Book(models.Model): 
    _sql_constraints = [
        ('library_book_name_date_uq',  # Constraint ...