Overview of Owl Hooks in Odoo 18

With the continuous evolution of Odoo's frontend framework, Owl (Odoo Web Library) has become a crucial component for building dynamic and reactive user interfaces. Introduced in earlier versions of Odoo, Owl is a modern, lightweight JavaScript framework inspired by Vue.js and React. It is designed to enhance Odoo’s UI capabilities by providing a component-based architecture and state management.

In Odoo 18, Owl has undergone further refinements, offering improved performance, maintainability, and developer experience. One of the key features that make Owl powerful is Hooks—a mechanism that allows developers to reuse logic, manage state, and interact efficiently with the component lifecycle.

In this blog, we will explore Owl Hooks in Odoo 18, how they work, and how you can leverage them to build efficient and modular UI components. We will cover essential hooks, their use cases, and examples to help you understand their implementation in real-world Odoo applications.

1. useAssets

The useAssets hook is used for lazy loading assets in Odoo, ensuring that resources like scripts and styles are loaded only when needed.

Location: @web/core/assets

2. useAutofocus

The useAutofocus hook automatically sets focus on an element marked with t-ref="autofocus" when it appears on the screen, but only if it wasn’t previously displayed.

It is imported from @web/core/utils/hooks and returns the referenced element, ensuring a smoother user experience by directing focus where needed.

import { useAutofocus } from "@web/core/utils/hooks";
class Comp {
  setup() {
    this.inputRef = useAutofocus();
  }
  static template = "Comp";
}

<t t-name="Comp">
  <input t-ref="autofocus" type="text"/>
</t>

3. useBus

The useBus hook is used to add an event listener to a bus and automatically removes it when the component is unmounted. This prevents memory leaks by ensuring proper cleanup.

It is located in @web/core/utils/hooks and follows this syntax:

import { useBus } from "@web/core/utils/hooks";
class MyComponent {
  setup() {
    useBus(this.env.bus, "some-event", event => {
      console.log(event);
    });
  }
}

useBus(bus, eventName, callback) – where bus is the event bus, eventName is the event to listen for, and callback is the function that runs when the event occurs.

4. usePager

The usePager hook is used to set up pagination in a view's control panel, ensuring that the necessary environment configuration is applied for the pager to function correctly.

It is imported from @web/search/pager_hook and helps manage navigation through paginated data smoothly.

import { usePager } from "@web/search/pager_hook";
class CustomView {
  setup() {
    const state = owl.hooks.useState({
      offset: 0,
      limit: 80,
      total: 50,
    });
    usePager(() => {
      return {
        offset: this.state.offset,
        limit: this.state.limit,
        total: this.state.total,
        onUpdate: (newState) => {
          Object.assign(this.state, newState);
        },
      };
    });
  }
}

5. usePosition

The usePosition hook helps position an HTML element (the popper) relative to another element (the reference). It automatically updates the position when the window is resized or scrolled, ensuring proper alignment.

It is imported from @web/core/position_hook, and the popper element should be referenced using t-ref with useRef.

import { usePosition } from "@web/core/position_hook";
import { Component, xml } from "@odoo/owl";
class MyPopover extends Component {
  static template = xml`
    <div t-ref="popper">
      I am positioned through a wonderful hook!
    </div>
  `;
  setup() {
    // Here, the reference is the target props, which is an HTMLElement
    usePosition(this.props.target);
  }
}

6. usePosition

The useSpellCheck hook enables spell checking for any HTML element with the contenteditable attribute. When the element (referenced with t-ref="spellcheck") gains focus, spell check is activated. Once it loses focus, spell check is disabled, and the red outline is removed, improving readability.

To completely disable spell check on certain elements, set spellcheck="false" directly on the element.

In the following example, the spellcheck will be enabled on the first input, the textarea and the div with contenteditable="true"

import { useSpellCheck } from "@web/core/utils/hooks";
class Comp {
  setup() {
    this.simpleRef = useSpellCheck();
    this.customRef = useSpellCheck({ refName: "custom" });
    this.nodeRef = useSpellCheck({ refName: "container" });
  }
  static template = "Comp";
}

<t t-name="Comp">
  <input t-ref="spellcheck" type="text"/>
  <textarea t-ref="custom"/>
  <div t-ref="container">
    <input type="text" spellcheck="false"/>
    <div contenteditable="true"/>
  </div>
</t>

Owl hooks in Odoo 18 provide a powerful way to manage component behavior, enhance interactivity, and improve code reusability. From automatically focusing input fields with useAutofocus to efficiently handling events with useBus, these hooks simplify frontend development in Odoo. Features like usePager for pagination, usePosition for dynamic positioning, and useSpellCheck for better text editing further enhance the user experience.

By leveraging these hooks, developers can build more efficient, scalable, and user-friendly Odoo applications. As Odoo continues to evolve, mastering these hooks will be essential for creating dynamic and responsive interfaces.

To read more about An Overview of OWL Components in Odoo 18, refer to our blog An Overview of OWL Components in Odoo 18.