Building Your First Owl.js Component in Odoo 17

Understanding Owl.js

• Reactive Framework: Owl.js is a component-based JavaScript framework developed by Odoo. It's inspired by modern frameworks like React and Vue.js. Owl components react to changes in data, updating the user interface seamlessly.
• Component Structure: Owl components are self-contained building blocks consisting of:
  • JavaScript logic (defining behavior)
  • XML template (defining structure)

Prerequisites

• Odoo 17 development environment setup
• Basic understanding of HTML, JavaScript, and XML.

Step-by-Step Guide

1. Create a Custom Module:
   • Set up a basic Odoo module with the necessary manifest files.
2. Define the JavaScript File:
   • Create a JavaScript file (e.g., my_component.js) within the /static/src/js directory of your module.
   • Here's a simple counter component example:

   const { useState } = owl.hooks;
   const { xml } = owl.tags;
   
   class Counter extends owl.Component {
       static template = xml`
           <div class="counter">
               <button t-on-click="decrement">-</button>
               <span t-esc="state.count" />
               <button t-on-click="increment">+</button>
           </div>`;
   
       setup() {
           this.state = useState({ count: 0 });
       }
   
       decrement() {
           this.state.count--;
       }
   
       increment() {
           this.state.count++;
       }
   }
   

3. Define the XML Template
   • Optionally, create a corresponding XML file (e.g., my_component.xml) in the /static/src/xml directory to hold your template (if not embedded in the JavaScript file as above).
4. Load Your Component
   • Update your module's assets file (e.g., assets_backend.xml) to load the JavaScript file:

   <templates>
       <t t-name="web.assets_backend">
           <xpath expr="." position="inside">
               <script type="text/javascript" src="/your_module/static/src/js/my_component.js"/>
           </xpath>
       </t>
   </templates>
   

5. Use the Component in a View:
   • Integrate the component into a relevant Odoo view:
    

   <div class="my-custom-container">
       <Counter/>
   </div>
   

Explanation

• Import Statements: You import the necessary hooks (useState) and template tags (xml) from the owl library.
• Counter Class: Defines your Owl component.
• template: Contains the HTML structure of the component. t- attributes provide dynamic behaviors:
  • t-esc: Displays the value of state.count
  • t-on-click: Calls the increment or decrement methods.
• setup(): Initializes the component's state using the useState hook.
• Methods: The increment and decrement methods modify the state, causing re-rendering.

Key Points

• State variables defined with useState trigger re-rendering when updated.
• Odoo uses a virtual DOM for efficient updates.
• Owl offers a rich set of features for complex components, including lifecycle hooks, props, and more.

Remember to install and restart your module to see the component in action!

Source credit

https://www.odoo.com/documentation/17.0/developer/reference/frontend/owl_components.html

https://github.com/odoo/owl/blob/master/doc/readme.md