Chapter 4: Models And Basic Fields

At the end of the previous chapter, we were able to create an Odoo module. However, at this point it is still an empty shell which doesn’t allow us to store any data. In our real estate module, we want to store the information related to the properties (name, description, price, living area…) in a database. The Odoo framework provides tools to facilitate database interactions.

Before moving forward in the exercise, make sure the estate module is installed, i.e. it must appear as ‘Installed’ in the Apps list.

Object-Relational Mapping

Reference: the documentation related to this topic can be found in the Models API.

$ psql -d rd-demo
rd-demo=# SELECT COUNT(*) FROM estate_property;
count
-------
    0
(1 row)

A key component of Odoo is the ORM layer. This layer avoids having to manually write most SQL and provides extensibility and security services2.

Business objects are declared as Python classes extending Model, which integrates them into the automated persistence system.

Models can be configured by setting attributes in their definition. The most important attribute is _name, which is required and defines the name for the model in the Odoo system. Here is a minimum definition of a model:

from odoo import models

class TestModel(models.Model):
    _name = "test.model"

This definition is enough for the ORM to generate a database table named test_model. The . in the model _name is automatically converted into a _ by the ORM. By convention all models are located in a models directory and each model is defined in its own Python file.

Take a look at how the crm_recurring_plan table is defined and how the corresponding Python file is imported:

1. The model is defined in the file crm/models/crm_recurring_plan.py (see here)

2. The file crm_recurring_plan.py is imported in crm/models/__init__.py (see here)

3. The folder models is imported in crm/__init__.py (see here)

Any modification of the Python files requires a restart of the Odoo server. When we restart the server, we will add the parameters -d and -u:

$ ./odoo-bin --addons-path=../custom,../enterprise/,addons -d rd-demo -u estate

-u estate means we want to upgrade the estate module, i.e. the ORM will apply database schema changes. In this case it creates a new table. -d rd-demo means that the upgrade should be performed on the rd-demo database. -u should always be used in combination with -d.

During the startup you should see the following warnings:

...
WARNING rd-demo odoo.models: The model estate.property has no _description
...
WARNING rd-demo odoo.modules.loading: The model estate.property has no access rules, consider adding one...
...

If this is the case, then you should be good! To be sure, double check with psql as demonstrated in the Goal.

Model fields

Reference: the documentation related to this topic can be found in the Fields API.

Fields are used to define what the model can store and where they are stored. Fields are defined as attributes in the model class:

from odoo import fields, models

class TestModel(models.Model):
    _name = "test.model"
    _description = "Test Model"

    name = fields.Char()

The name field is a Char which will be represented as a Python unicode str and a SQL VARCHAR.

Types

$ psql -d rd-demo

rd-demo=# \d estate_property;
                                            Table "public.estate_property"
    Column       |            Type             | Collation | Nullable |                   Default
--------------------+-----------------------------+-----------+----------+---------------------------------------------
id                 | integer                     |           | not null | nextval('estate_property_id_seq'::regclass)
create_uid         | integer                     |           |          |
create_date        | timestamp without time zone |           |          |
write_uid          | integer                     |           |          |
write_date         | timestamp without time zone |           |          |
name               | character varying           |           |          |
description        | text                        |           |          |
postcode           | character varying           |           |          |
date_availability  | date                        |           |          |
expected_price     | double precision            |           |          |
selling_price      | double precision            |           |          |
bedrooms           | integer                     |           |          |
living_area        | integer                     |           |          |
facades            | integer                     |           |          |
garage             | boolean                     |           |          |
garden             | boolean                     |           |          |
garden_area        | integer                     |           |          |
garden_orientation | character varying           |           |          |
Indexes:
    "estate_property_pkey" PRIMARY KEY, btree (id)
Foreign-key constraints:
    "estate_property_create_uid_fkey" FOREIGN KEY (create_uid) REFERENCES res_users(id) ON DELETE SET NULL
    "estate_property_write_uid_fkey" FOREIGN KEY (write_uid) REFERENCES res_users(id) ON DELETE SET NULL

There are two broad categories of fields: ‘simple’ fields, which are atomic values stored directly in the model’s table, and ‘relational’ fields, which link records (of the same or different models).

Simple field examples are Boolean, Float, Char, Text, Date and Selection.

When the fields are added to the model, restart the server with -u estate

$ ./odoo-bin --addons-path=../custom,../enterprise/,addons -d rd-demo -u estate

Connect to psql and check the structure of the table estate_property. You’ll notice that a couple of extra fields were also added to the table. We will revisit them later.

Common Attributes

rd-demo=# \d estate_property;
                                            Table "public.estate_property"
    Column       |            Type             | Collation | Nullable |                   Default
--------------------+-----------------------------+-----------+----------+---------------------------------------------
...
name               | character varying           |           | not null |
...
expected_price     | double precision            |           | not null |
...

Much like the model itself, fields can be configured by passing configuration attributes as parameters:

name = fields.Char(required=True)

Some attributes are available on all fields, here are the most common ones:

string (str, default: field’s name)

The label of the field in UI (visible by users).

required (bool, default: False)

If True, the field can not be empty. It must either have a default value or always be given a value when creating a record.

help (str, default: '')

Provides long-form help tooltip for users in the UI.

index (bool, default: False)

Requests that Odoo create a database index on the column.

Automatic Fields

Reference: the documentation related to this topic can be found in Automatic fields.

You may have noticed your model has a few fields you never defined. Odoo creates a few fields in all models1. These fields are managed by the system and can’t be written to, but they can be read if useful or necessary:

id (Id)

The unique identifier for a record of the model.

create_date (Datetime)

Creation date of the record.

create_uid (Many2one)

User who created the record.

write_date (Datetime)

Last modification date of the record.

write_uid (Many2one)

User who last modified the record.

Now that we have created our first model, let’s add some security!

1

it is possible to disable the automatic creation of some fields

2

writing raw SQL queries is possible, but requires caution as this bypasses all Odoo authentication and security mechanisms.