Models

A model represents a single business logic or concept. It contains fields and defines the behaviors of the data. Most of the time, each model stores data in a single database table.

The basics:

  • Each model is a Python class that subclasses one of trytond.model.model.Model.
  • Fields are defined as model attributes.
  • Tryton generates the table definitions and provides an API to access the data.

Example

This example defines a Party model which has a name and a code fields:

from trytond.model import ModelView, ModelSQL, fields

class Party(ModelSQL, ModelView):
    "Party"
    _description = __doc__
    _name = "party.party"
    name = fields.Char('Name')
    code = fields.Char('Code')

Party()

Instantiating the class registers the model class in the framework. Later the class will be instantiated once per database and stored in the Pool. Model instances are essentially accessors to records.

Model attributes define meta-information of the model. They are class attributes starting with an underscore. Some model properties are instance attributes allowing to update them at other places in the framework.