.. _tutorial-module-model: Define model ============ The :ref:`models <ref-models>` are the base objects of a module to store and display data. The :class:`~trytond.model.ModelSQL` is the base class that implements the persistence in the SQL database. The :class:`~trytond.model.ModelView` is the base class that implements the view layer. And of course, a model would be useless without its :ref:`fields <ref-models-fields>`. Let's start with a simple model to store the opportunities with a description, a start and end date, a link to a party and an optional comment. Our model in :file:`opportunity.py` file currently looks like this: .. code-block:: python from trytond.model import ModelSQL, fields class Opportunity(ModelSQL): "Opportunity" __name__ = 'training.opportunity' _rec_name = 'description' description = fields.Char("Description", required=True) start_date = fields.Date("Start Date", required=True) end_date = fields.Date("End Date") party = fields.Many2One('party.party', "Party", required=True) comment = fields.Text("Comment") As you can see a Model must have a :attr:`~trytond.model.Model.__name__` attribute. This name is used to make reference to this object. It is also used to build the name of the SQL table to store the opportunity records in the database. The :attr:`~trytond.model.Model._rec_name` attribute defines the field that will be used to compute the name of the record. The name of the record is its textual representation. The ``party`` field is a relation field (Many2One_) to another Model of Tryton named ``party.party``. This model is defined by the ``party`` module. .. _Many2One: https://en.wikipedia.org/wiki/Many-to-one Register the model in the Pool ------------------------------ Once a Tryton model is defined, you need to register it in the :class:`~trytond.pool.Pool`. This is done in the :file:`__init__.py` file of your module with the following code: .. code-block:: python from trytond.pool import Pool from . import opportunity def register(): Pool.register( opportunity.Opportunity, module='opportunity', type_='model') Models in the pool are inspected by Tryton when activating or updating a module in order to create or update the schema of the table in the database. Activate the opportunity module ------------------------------- Now that we have a basic module, we will use it to create the related table into the :ref:`database created <tutorial-module-setup-database>`. First we must edit the :file:`tryton.cfg` file to specify that this module depends on the ``party`` and ``ir`` module. We need to do this because the ``Opportunity`` model contains the ``party`` field which refers to the ``Party`` model. And we always need the ``ir`` module which is always included in Tryton server. Here is the content of our :file:`tryton.cfg` file: .. code-block:: ini [tryton] version=x.y.0 depends: ir party As we defined a new dependency, we must refresh the installation with: .. code-block:: console $ python -m pip install --editable opportunity Now we can activate the ``opportunity`` module and its dependencies: .. code-block:: console $ trytond-admin -d test -u opportunity --activate-dependencies This step has created the tables into your database. You can check it with the :command:`sqlite3` command line: .. code-block:: console $ sqlite3 ~/db/test.sqlite '.schema training_opportunity' CREATE TABLE "training_opportunity" ( id INTEGER PRIMARY KEY AUTOINCREMENT, "comment" TEXT, "create_uid" INTEGER, "create_date" TIMESTAMP, "description" VARCHAR, "end_date" DATE, "start_date" DATE, "write_date" TIMESTAMP, "party" INTEGER, "write_uid" INTEGER); The next step will be :ref:`displaying record <tutorial-module-view>`.