documentation/content/developer/reference/frontend/hooks.rst
Bruno Boi 43d838d826 [IMP] developer: more info for usePosition JS hook
closes odoo/documentation#1305

Signed-off-by: Bruno Boi <boi@odoo.com>
2021-11-10 14:21:21 +00:00

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.. _frontend/hooks:
=====
Hooks
=====
`Owl hooks <https://github.com/odoo/owl/blob/master/doc/reference/hooks.md>`_ are a
way to factorize code, even if it depends on some component lifecycle. Most hooks
provided by Owl are related to the lifecycle of a component, but some of them (such as
`useComponent <https://github.com/odoo/owl/blob/master/doc/reference/hooks.md#usecomponent>`_)
provide a way to build specific hooks.
Using these hooks, it is possible to build many customized hooks that help solve
a specific problem, or make some common tasks easier. The rest of this page
documents the list of hooks provided by the Odoo web framework.
.. list-table::
:widths: 30 70
:header-rows: 1
* - Name
- Short Description
* - :ref:`useAssets <frontend/hooks/useassets>`
- load assets
* - :ref:`useBus <frontend/hooks/usebus>`
- subscribe and unsubscribe to a bus
* - :ref:`usePosition <frontend/hooks/useposition>`
- position an element relative to a target
.. _frontend/hooks/useassets:
useAssets
=========
Location
--------
`@web/core/assets`
Description
-----------
See the section on :ref:`lazy loading assets <frontend/assets/lazy_loading>` for
more details.
.. _frontend/hooks/usebus:
useBus
======
Location
--------
`@web/core/utils/hooks`
Description
-----------
Add and clear an event listener to a bus. This hook ensures that
the listener is properly cleared when the component is unmounted.
.. code-block:: javascript
import { useBus } from "@web/core/utils/hooks";
class MyComponent {
setup() {
useBus(this.env.bus, "some-event", event => {
console.log(event);
});
}
}
API
---
.. js:function:: useBus(bus, eventName, callback)
:param EventBus bus: the target event bus
:param string eventName: the name of the event that we want to listen to
:param function callback: listener callback
.. _frontend/hooks/useposition:
usePosition
===========
Location
--------
`@web/core/position/position_hook`
Description
-----------
Helps positioning a component (or a specific HTMLElement) relatively to a target
HTMLElement. This hook ensures the positioning is updated when the window is
resized/scrolled.
.. code-block:: javascript
import { usePosition } from "@web/core/position/position_hook";
class MyPopover {
setup() {
// Here, the target is an HTMLElement
usePosition(this.props.target);
}
}
MyPopover.template = owl.tags.xml`<div>I am positioned through a wonderful hook!</div>`
.. note::
The following CSS classes can be used to style the target HTMLElement:
- `o-popper-position`
- `o-popper-position--{D}{V}` where `{D}` and `{V}` are replaced by the first letter of the corresponding Direction and Variant (see Options table below for valid directions and variants). E.g.: for position `bottom-end`, the class name will be `o-popper-position--be`.
API
---
.. js:function:: usePosition(reference[, options])
:param reference: the target HTMLElement to be positioned from
:type reference: HTMLElement or ()=>HTMLElement
:param Options options: the positioning options (see table below)
.. list-table::
:widths: 20 20 60
:header-rows: 1
* - Option
- Type
- Description
* - `popper`
- string | undefined
- this is the element that will get positioned. You can provide here a
`useRef reference <https://github.com/odoo/owl/blob/master/doc/reference/hooks.md#useref>`_.
If not provided, `this.el` is used (default: `undefined`).
* - `container`
- HTMLElement
- the container from which the popper is expected not to overflow. If
overflowing occurs, other popper positions are tried until a not
overflowing one is found. (default: the `<html/>` node)
* - `margin`
- number
- added margin between popper and reference elements (default: `0`)
* - `position`
- string
- the desired position. It is a string composed of one direction and one
variant separated by a dash character. Valid directions are: `top`,
`bottom`, `right`, `left`. Valid variants are: `start`,
`middle`, `end`. The variant can be omitted (default variant is
`middle`). Examples of valid positions: `right-end`, `top-start`,
`left-middle`, `left`. (default position: `bottom`)