Géry Debongnie
7538aeae0e
Before this commit, most of the time, components are destroyed when the
virtual dom is patched and a component node is removed. However, since
Owl is asynchronous and a component may take some time to get ready
(with onWillStart), it can happen that a component is created, then
before it is ready, it is recreated. In that case, the initial instance
has to be destroyed.
Before this commit, the destroy operation was done immediately, when we
cancel the current fibers. However, this means that we cannot have a
guarantee between micro task ticks that a component has not been
destroyed in the meantime.
For example, in Odoo, it is common to use the rpc service, which will
throw an error if called by a destroyed component. But because of the
possible destruction of a component at any time, the following code is
unsafe:
async loadSomeData() {
// guaranteed to be called when component is alive
await Promise.resolve();
// however here, component may have been destroyed
this.rpc(...)
}
So, to prevent this issue, we can slightly delay the destroy operation.
It is not entirely trivial, since we need to find a way to neutralize
the component in the meantime. But it seems like performing all that
kind of operation at the "commit" phase (so, the request animation frame
callback) makes sense to me.
So, this commit modifies the code to add a new component status
(cancelled) and use it to cancel components that are waiting to be
destroyed. These components will then be destroyed as soon as the
requestanimation frame starts, before all other dom operations.
🦉 Owl Framework 🦉
Class based components with hooks, reactive state and concurrent mode
Try it online! you can experiment with the Owl framework in an online playground.
Project Overview
The Odoo Web Library (Owl) is a smallish (~<20kb gzipped) UI framework built by Odoo for its products. 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 fine grained reactivity system similar to Vue,
- hooks
- fragments
- asynchronous rendering
Owl components are defined with ES6 classes and xml templates, uses an underlying virtual DOM, integrates beautifully with hooks, and the rendering is asynchronous.
Quick links:
- documentation,
- changelog (from Owl 1.x to 2.x),
- playground
Example
Here is a short example to illustrate interactive components:
const { Component, useState, mount, xml } = owl;
class Counter extends Component {
static template = xml`
<button t-on-click="() => state.value = state.value + props.increment">
Click Me! [<t t-esc="state.value"/>]
</button>`;
state = useState({ value: 0 });
}
class Root extends Component {
static template = xml`
<span>Hello Owl</span>
<Counter increment="2"/>`;
static components = { Counter };
}
mount(Root, 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.
Documentation
Learning Owl
Are you new to Owl? This is the place to start!
Reference
- Overview
- App
- Component
- Component Lifecycle
- Concurrency Model
- Dev mode
- Dynamic sub components
- Environment
- Error Handling
- Event Handling
- Form Input Bindings
- Fragments
- Hooks
- Loading Templates
- Mounting a component
- Portal
- Precompiling templates
- Props
- Props Validation
- Reactivity
- Rendering SVG
- Refs
- Slots
- Sub components
- Sub templates
- Templates (Qweb)
- Translations
- Utils
Other Topics
- Notes On Owl Architecture
- Comparison with React/Vue
- Why did Odoo build Owl?
- Changelog (from owl 1.x to 2.x)
- Notes on compiled templates
- Owl devtools extension
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:
Installing Owl devtools
The Owl devtools browser extension is also available in the release: Unzip the owl-devtools.zip file and follow the instructions depending on your browser:
Chrome
Go to your chrome extensions admin panel, activate developer mode and click on Load unpacked.
Select the devtools-chrome folder and that's it, your extension is active!
There is a convenient refresh button on the extension card (still on the same admin page) to update your code.
Do note that if you got some problems, you may need to completly remove and reload the extension to completly refresh the extension.
Firefox
Go to the address about:debugging#/runtime/this-firefox and click on Load temporary Add-on....
Select any file in the devtools-firefox folder and that's it, your extension is active!
Here, you can use the reload button to refresh the extension.
Note that you may have to open another window or reload your tab to see the extension working. Also note that the extension will only be active on pages that have a sufficient version of owl.