Géry Debongnie
398f9f4e53
From the beginning, Owl was designed to only call event handler on components that are mounted in the DOM. The main benefit is that if a component is destroyed, we are guaranteed to not execute any useless (or potentially dangerous code). However, there is one downside: if a component tree is being mounted, and a child component trigger an event in its mounted hook, then it cannot be caught by the parent, since the parent is technically not yet mounted. This may not be a good situation, but the point is that Owl unnecessarily prevent the handler to be called. We can fix this issue by simply checking if the component is not destroyed instead of checking that it is mounted. closes #809
🦉 OWL Framework 🦉
Class based components with hooks, reactive state and concurrent mode
Project Overview
The Odoo Web Library (OWL) is a smallish (~<20kb gzipped) UI framework intended to be the basis for the Odoo Web Client. Owl is a modern framework, written in Typescript, taking the best ideas from React and Vue in a simple and consistent way. Owl's main features are:
- a declarative component system,
- a reactivity system based on hooks,
- concurrent mode by default,
- a store and a frontend router
Owl components are defined with ES6 classes, they use QWeb templates, an underlying virtual DOM, integrates beautifully with hooks, and the rendering is asynchronous.
Try it online! An online playground is available at https://odoo.github.io/owl/playground to let you experiment with the Owl framework. There are some code examples to showcase some interesting features.
Owl is currently stable. Possible future changes are explained in the roadmap.
Why Owl?
Why did Odoo decide to make Yet Another Framework? This is really a question that deserves a long answer. But in short, we believe that while the current state of the art frameworks are excellent, they are not optimized for our use case, and there is still room for something else.
If you are interested in a comparison with React or Vue, you will find some more additional information here.
Example
Here is a short example to illustrate interactive components:
const { Component, useState, mount } = owl;
const { xml } = owl.tags;
class Counter extends Component {
static template = xml`
<button t-on-click="state.value++">
Click Me! [<t t-esc="state.value"/>]
</button>`;
state = useState({ value: 0 });
}
class App extends Component {
static template = xml`
<div>
<span>Hello Owl</span>
<Counter />
</div>`;
static components = { Counter };
}
mount(App, { target: document.body });
Note that the counter component is made reactive with the useState hook.
Also, all examples here uses the xml helper to define inline templates.
But this is not mandatory, many applications will load templates separately.
More interesting examples can be found on the playground application.
Design Principles
OWL is designed to be used in highly dynamic applications where changing requirements are common and code needs to be maintained by large teams.
- XML based: templates are based on the XML format, which allows interesting
applications. For example, they could be stored in a database and modified
dynamically with
xpaths. - templates compilation in the browser: this may not be a good fit for all applications, but if you need to generate dynamically user interfaces in the browser, this is very powerful. For example, a generic form view component could generate a specific form user interface for each various models, from a XML view.
- no toolchain required: this is extremely useful for some applications, if,
for various reasons (security/deployment/dynamic modules/specific assets tools),
it is not ok to use standard web tools based on
npm.
Owl is not designed to be fast nor small (even though it is quite good on those two topics). It is a no nonsense framework to build applications. There is only one way to define components (with classes). There is no black magic. It just works.
Documentation
A complete documentation for Owl can be found here:
Some of the most important pages are:
Installing Owl
Owl is available on npm and can be installed with the following command:
npm install @odoo/owl
If you want to use a simple <script> tag, the last release can be downloaded here:
License
OWL is LGPL licensed.