Building Custom Odoo Modules: Developer Tutorial

Odoo's module system is one of the most powerful extension frameworks in the ERP world. Every feature in Odoo — from accounting to inventory to CRM — is a module. This means that building custom functionality follows the exact same patterns used by Odoo's own developers, giving you access to the full framework without forking the core.

This tutorial covers the complete lifecycle of a custom Odoo 19 module: from scaffolding the directory structure and defining models, to creating views, securing access, and deploying to production. By the end, you'll have a working module that follows Odoo 19 Enterprise conventions and is ready for the marketplace.

Key Takeaways

• Every Odoo module is a Python package with a __manifest__.py descriptor
• Models inherit from models.Model and map directly to PostgreSQL tables
• Views are defined in XML and reference model fields by name
• Security is enforced through ir.model.access CSV and record rules
• Wizards (TransientModel) handle multi-step user interactions
• Computed fields and onchange methods update related fields dynamically
• Automated actions and scheduled jobs run server-side logic on triggers
• Module dependencies ensure correct load order and feature availability

---

Module Structure and Scaffolding

Every Odoo module is a directory with a specific structure. Use Odoo's built-in scaffold command to generate the boilerplate:

# From your Odoo addons directory
python odoo-bin scaffold my_module /path/to/addons

This generates:

my_module/
├── __init__.py
├── __manifest__.py
├── models/
│   ├── __init__.py
│   └── my_model.py
├── views/
│   └── my_model_views.xml
├── security/
│   ├── ir.model.access.csv
│   └── my_module_security.xml
├── data/
│   └── my_module_data.xml
├── wizard/
│   └── my_wizard.py
├── report/
│   └── my_report.xml
└── static/
    └── src/
        └── js/

The manifest file (__manifest__.py)

{
    'name': 'My Custom Module',
    'version': '19.0.1.0.0',
    'summary': 'Short description for module list',
    'description': """
        Extended description of what this module does.
        Can be multi-line RST text.
    """,
    'author': 'ECOSIRE Private Limited',
    'website': 'https://ecosire.com',
    'category': 'Sales/CRM',
    'depends': ['sale', 'account', 'stock'],
    'data': [
        'security/ir.model.access.csv',
        'security/my_module_security.xml',
        'data/my_module_data.xml',
        'views/my_model_views.xml',
        'views/menu_views.xml',
        'report/my_report.xml',
        'wizard/my_wizard_views.xml',
    ],
    'assets': {
        'web.assets_backend': [
            'my_module/static/src/js/my_widget.js',
            'my_module/static/src/css/my_styles.css',
        ],
    },
    'license': 'OPL-1',
    'installable': True,
    'application': False,
    'auto_install': False,
    'price': 249.0,
    'currency': 'USD',
}

Version numbering convention: {odoo_version}.{major}.{minor}.{patch}. Always start at 19.0.1.0.0 for new modules.

---

Defining Models

Models are the heart of any Odoo module. They define the data structure and business logic.

# models/service_request.py
from odoo import api, fields, models
from odoo.exceptions import ValidationError, UserError

class ServiceRequest(models.Model):
    _name = 'my.service.request'
    _description = 'Service Request'
    _inherit = ['mail.thread', 'mail.activity.mixin']
    _order = 'date_request desc, name'
    _rec_name = 'name'

    name = fields.Char(
        string='Reference',
        required=True,
        copy=False,
        readonly=True,
        default=lambda self: self.env['ir.sequence'].next_by_code('my.service.request')
    )
    state = fields.Selection([
        ('draft', 'Draft'),
        ('submitted', 'Submitted'),
        ('in_progress', 'In Progress'),
        ('done', 'Completed'),
        ('cancelled', 'Cancelled'),
    ], string='Status', default='draft', tracking=True)

    partner_id = fields.Many2one(
        'res.partner', string='Customer',
        required=True, tracking=True,
        domain=[('customer_rank', '>', 0)]
    )
    user_id = fields.Many2one(
        'res.users', string='Assigned To',
        default=lambda self: self.env.user
    )
    date_request = fields.Datetime(
        string='Request Date',
        default=fields.Datetime.now,
        required=True
    )
    date_deadline = fields.Date(string='Deadline')
    description = fields.Html(string='Description')
    priority = fields.Selection([
        ('0', 'Normal'),
        ('1', 'Low'),
        ('2', 'High'),
        ('3', 'Urgent'),
    ], string='Priority', default='0')
    tag_ids = fields.Many2many(
        'my.service.tag', string='Tags'
    )
    line_ids = fields.One2many(
        'my.service.request.line', 'request_id',
        string='Service Lines'
    )
    amount_total = fields.Float(
        string='Total Amount',
        compute='_compute_amount_total',
        store=True
    )
    company_id = fields.Many2one(
        'res.company', string='Company',
        required=True,
        default=lambda self: self.env.company
    )

    @api.depends('line_ids.subtotal')
    def _compute_amount_total(self):
        for request in self:
            request.amount_total = sum(request.line_ids.mapped('subtotal'))

    @api.constrains('date_deadline', 'date_request')
    def _check_deadline(self):
        for record in self:
            if record.date_deadline and record.date_request:
                if record.date_deadline < record.date_request.date():
                    raise ValidationError("Deadline cannot be before the request date.")

    @api.onchange('partner_id')
    def _onchange_partner_id(self):
        if self.partner_id:
            self.user_id = self.partner_id.user_id or self.env.user

    def action_submit(self):
        for record in self:
            if not record.line_ids:
                raise UserError("Cannot submit a request without service lines.")
            record.state = 'submitted'
            record.message_post(body="Service request submitted for processing.")

    def action_start_progress(self):
        self.write({'state': 'in_progress'})

    def action_mark_done(self):
        self.write({'state': 'done'})

    def action_cancel(self):
        for record in self:
            if record.state == 'done':
                raise UserError("Cannot cancel a completed request.")
            record.state = 'cancelled'

    @api.model_create_multi
    def create(self, vals_list):
        for vals in vals_list:
            if vals.get('name', 'New') == 'New':
                vals['name'] = self.env['ir.sequence'].next_by_code(
                    'my.service.request'
                ) or 'New'
        return super().create(vals_list)

Service Request Line model:

class ServiceRequestLine(models.Model):
    _name = 'my.service.request.line'
    _description = 'Service Request Line'

    request_id = fields.Many2one(
        'my.service.request', string='Request',
        required=True, ondelete='cascade'
    )
    product_id = fields.Many2one(
        'product.product', string='Service',
        required=True,
        domain=[('type', '=', 'service')]
    )
    description = fields.Text(string='Description')
    quantity = fields.Float(string='Quantity', default=1.0)
    price_unit = fields.Float(string='Unit Price')
    subtotal = fields.Float(
        string='Subtotal',
        compute='_compute_subtotal',
        store=True
    )

    @api.depends('quantity', 'price_unit')
    def _compute_subtotal(self):
        for line in self:
            line.subtotal = line.quantity * line.price_unit

    @api.onchange('product_id')
    def _onchange_product_id(self):
        if self.product_id:
            self.price_unit = self.product_id.lst_price
            self.description = self.product_id.description_sale

---

Creating Views

Views define how records are displayed in the UI. Odoo uses XML to describe forms, lists, kanban boards, and more.

<!-- views/service_request_views.xml -->
<odoo>
    <!-- Form View -->
    <record id="view_service_request_form" model="ir.ui.view">
        <field name="name">my.service.request.form</field>
        <field name="model">my.service.request</field>
        <field name="arch" type="xml">
            <form string="Service Request">
                <header>
                    <button name="action_submit" string="Submit"
                            type="object" class="oe_highlight"
                            invisible="state != 'draft'"/>
                    <button name="action_start_progress" string="Start"
                            type="object" class="oe_highlight"
                            invisible="state != 'submitted'"/>
                    <button name="action_mark_done" string="Mark Done"
                            type="object" class="oe_highlight"
                            invisible="state != 'in_progress'"/>
                    <button name="action_cancel" string="Cancel"
                            type="object"
                            invisible="state in ['done', 'cancelled']"/>
                    <field name="state" widget="statusbar"
                           statusbar_visible="draft,submitted,in_progress,done"/>
                </header>
                <sheet>
                    <div class="oe_title">
                        <h1>
                            <field name="name" readonly="1"/>
                        </h1>
                    </div>
                    <group>
                        <group>
                            <field name="partner_id"
                                   options="{'no_create': True}"/>
                            <field name="user_id"/>
                            <field name="priority" widget="priority"/>
                        </group>
                        <group>
                            <field name="date_request"/>
                            <field name="date_deadline"/>
                            <field name="company_id" groups="base.group_multi_company"/>
                        </group>
                    </group>
                    <field name="tag_ids" widget="many2many_tags"/>
                    <notebook>
                        <page string="Service Lines">
                            <field name="line_ids">
                                <tree editable="bottom">
                                    <field name="product_id"/>
                                    <field name="description"/>
                                    <field name="quantity"/>
                                    <field name="price_unit"/>
                                    <field name="subtotal" readonly="1"/>
                                </tree>
                            </field>
                            <group class="oe_subtotal_footer">
                                <field name="amount_total"
                                       widget="monetary"
                                       class="oe_subtotal_footer_separator"/>
                            </group>
                        </page>
                        <page string="Description">
                            <field name="description" widget="html"
                                   placeholder="Detailed description..."/>
                        </page>
                    </notebook>
                </sheet>
                <div class="oe_chatter">
                    <field name="message_follower_ids"/>
                    <field name="activity_ids"/>
                    <field name="message_ids"/>
                </div>
            </form>
        </field>
    </record>

    <!-- List View -->
    <record id="view_service_request_tree" model="ir.ui.view">
        <field name="name">my.service.request.list</field>
        <field name="model">my.service.request</field>
        <field name="arch" type="xml">
            <tree string="Service Requests" decoration-danger="state=='cancelled'"
                  decoration-success="state=='done'">
                <field name="name"/>
                <field name="partner_id"/>
                <field name="user_id" optional="show"/>
                <field name="priority" widget="priority"/>
                <field name="date_request"/>
                <field name="date_deadline" optional="show"/>
                <field name="amount_total" sum="Total"/>
                <field name="state" widget="badge"
                       decoration-info="state=='draft'"
                       decoration-warning="state=='submitted'"
                       decoration-primary="state=='in_progress'"
                       decoration-success="state=='done'"
                       decoration-danger="state=='cancelled'"/>
            </tree>
        </field>
    </record>

    <!-- Search View -->
    <record id="view_service_request_search" model="ir.ui.view">
        <field name="name">my.service.request.search</field>
        <field name="model">my.service.request</field>
        <field name="arch" type="xml">
            <search>
                <field name="name" string="Reference"/>
                <field name="partner_id"/>
                <field name="user_id"/>
                <filter string="My Requests" name="my_requests"
                        domain="[('user_id', '=', uid)]"/>
                <filter string="In Progress" name="in_progress"
                        domain="[('state', '=', 'in_progress')]"/>
                <filter string="Urgent" name="urgent"
                        domain="[('priority', '=', '3')]"/>
                <separator/>
                <filter string="This Month" name="this_month"
                        domain="[('date_request', '&gt;=',
                                  (context_today() - relativedelta(day=1)).strftime('%Y-%m-%d'))]"/>
                <group expand="0" string="Group By">
                    <filter string="Customer" name="group_partner"
                            context="{'group_by': 'partner_id'}"/>
                    <filter string="Status" name="group_state"
                            context="{'group_by': 'state'}"/>
                    <filter string="Assigned To" name="group_user"
                            context="{'group_by': 'user_id'}"/>
                </group>
            </search>
        </field>
    </record>

    <!-- Action -->
    <record id="action_service_request" model="ir.actions.act_window">
        <field name="name">Service Requests</field>
        <field name="res_model">my.service.request</field>
        <field name="view_mode">list,form,kanban</field>
        <field name="search_view_id" ref="view_service_request_search"/>
        <field name="context">{'search_default_in_progress': 1}</field>
    </record>
</odoo>

---

Security Configuration

Security is mandatory for any production module.

Access control list (security/ir.model.access.csv):

id,name,model_id:id,group_id:id,perm_read,perm_write,perm_create,perm_unlink
access_service_request_user,service.request.user,model_my_service_request,base.group_user,1,1,1,0
access_service_request_manager,service.request.manager,model_my_service_request,base.group_system,1,1,1,1
access_service_request_line_user,service.request.line.user,model_my_service_request_line,base.group_user,1,1,1,1

Record rules (security/my_module_security.xml):

<odoo>
    <!-- Users can only see their own requests unless they're managers -->
    <record id="rule_service_request_own" model="ir.rule">
        <field name="name">Service Request: Own Records</field>
        <field name="model_id" ref="model_my_service_request"/>
        <field name="domain_force">
            [('user_id', '=', user.id)]
        </field>
        <field name="groups" eval="[(4, ref('base.group_user'))]"/>
        <field name="perm_read" eval="True"/>
        <field name="perm_write" eval="True"/>
        <field name="perm_create" eval="True"/>
        <field name="perm_unlink" eval="False"/>
    </record>
</odoo>

---

Wizards (TransientModel)

Wizards are temporary forms for guided multi-step actions.

# wizard/service_request_wizard.py
from odoo import api, fields, models

class ServiceRequestBulkAssign(models.TransientModel):
    _name = 'my.service.request.bulk.assign'
    _description = 'Bulk Assign Service Requests'

    user_id = fields.Many2one(
        'res.users', string='Assign To', required=True
    )
    request_ids = fields.Many2many(
        'my.service.request', string='Requests',
        default=lambda self: self.env.context.get('active_ids', [])
    )
    note = fields.Text(string='Note')

    def action_assign(self):
        self.request_ids.write({'user_id': self.user_id.id})
        if self.note:
            for request in self.request_ids:
                request.message_post(body=self.note)
        return {'type': 'ir.actions.act_window_close'}

---

Automated Actions and Sequences

Sequence for auto-numbering:

<record id="seq_service_request" model="ir.sequence">
    <field name="name">Service Request</field>
    <field name="code">my.service.request</field>
    <field name="prefix">SRQ/%(year)s/</field>
    <field name="padding">5</field>
    <field name="company_id" eval="False"/>
</record>

Scheduled action (cron job):

# In the model
def _cron_remind_overdue_requests(self):
    overdue = self.search([
        ('state', 'in', ['submitted', 'in_progress']),
        ('date_deadline', '<', fields.Date.today()),
    ])
    for request in overdue:
        request.activity_schedule(
            'mail.mail_activity_data_warning',
            summary='Overdue Service Request',
            user_id=request.user_id.id
        )

<record id="ir_cron_remind_overdue" model="ir.cron">
    <field name="name">Remind Overdue Service Requests</field>
    <field name="model_id" ref="model_my_service_request"/>
    <field name="state">code</field>
    <field name="code">model._cron_remind_overdue_requests()</field>
    <field name="interval_number">1</field>
    <field name="interval_type">days</field>
    <field name="numbercall">-1</field>
    <field name="active">True</field>
</record>

---

Frequently Asked Questions

What is the difference between models.Model, models.TransientModel, and models.AbstractModel?

models.Model creates a permanent table in the database. models.TransientModel creates a temporary table cleared periodically (used for wizards). models.AbstractModel creates no table — it's a mixin that other models can inherit to gain methods and fields without creating a separate table.

How do I extend an existing Odoo model without modifying core code?

Use _inherit with the existing model name and omit _name. This adds your fields and methods to the existing model: class SaleOrder(models.Model): _inherit = 'sale.order'. To create a new model that copies another's behavior as a starting point, use both _name (new name) and _inherit (source model).

How should I handle migrations when my module's data model changes?

Create a migration script in my_module/migrations/{version}/pre-migrate.py or post-migrate.py. These scripts run automatically during module update. For column renames, use openupgradelib helpers. Always test migrations on a copy of the production database before applying to production.

Can I override existing Odoo views without modifying core XML files?

Yes. Use inherit_id to reference the view you want to extend, then use xpath expressions to locate the element and position attribute (before, after, inside, replace, attributes) to specify the modification. This keeps your changes isolated and upgrade-safe.

How do I make a field company-specific in a multi-company environment?

Use company_dependent=True on the field definition: my_field = fields.Char(company_dependent=True). This stores a separate value per company, so Company A and Company B can have different values for the same record. This is used for pricelists, tax accounts, and other company-specific configurations.

What is the correct way to log messages and debug during development?

Use Python's logging module: import logging; _logger = logging.getLogger(__name__). Use _logger.info(), _logger.warning(), _logger.error() for different severity levels. Never use print() statements in production code. In development, run Odoo with --log-level=debug to see all debug output.

---

Next Steps

Building a production-ready Odoo module requires deep knowledge of the framework, PostgreSQL performance considerations, upgrade-safe patterns, and thorough testing. Modules intended for the Odoo marketplace undergo additional validation for security, performance, and code quality.

ECOSIRE develops custom Odoo 19 Enterprise modules for specific business requirements — from specialized industry workflows to marketplace connector modules. Our development team follows Odoo's official coding guidelines, includes comprehensive unit tests, and delivers modules with full documentation.

Commission a Custom Odoo Module from ECOSIRE →

Share your requirements and we'll scope the development effort, provide a timeline, and deliver a module that integrates cleanly with your Odoo 19 Enterprise installation.