10 unstable releases (3 breaking)
0.3.3 | Sep 29, 2024 |
---|---|
0.3.2 | Jun 2, 2024 |
0.3.0 | May 31, 2024 |
0.2.2 | May 25, 2024 |
0.0.4 | May 12, 2024 |
#1032 in WebAssembly
Used in dioxus-web-component
49KB
1K
SLoC
dioxus-web-component-macro
Provide a proc macro to build Dioxus web component.
Example
The macro replaces the Dioxus #[component]
macro.
use dioxus::prelude::*;
use dioxus_web_component::{web_component, DioxusWebComponent};
use wasm_bindgen::prelude::*;
#[web_component]
fn MyWebComponent(
attr: Option<String>,
event: EventHandler<i64>,
) -> Element {
rsx ! {
div {
// ...
}
}
}
#[wasm_bindgen(main)]
pub fn main() {
// Register the web component (aka custom element)
register_my_web_component();
}
<!-- include the script generated with wasm-pack -->
<script type="module" src="my-web-component.js"></script>
<!-- in the body -->
<my-web-component attr="plop"></my-web-component>
Usage
Tag
The custom element tag is built from the component name.
By default, the tag is the kebab-case version of the name.
For example, MyWebComponent
becomes my-web-component
.
You can change the default behavior with the tag
attribute.
use dioxus::prelude::*;
use dioxus_web_component::{web_component, DioxusWebComponent};
#[web_component(tag = "plop-component")]
fn MyWebComponent(
// ...
) -> Element { todo!() }
<!-- in the body -->
<plop-component></plop-component>
ℹ️ INFO: the custom element tag name has constraints. The macro checks the validity of the tag for you. See MDN - Valid custom element names
Style
You can provide the web component style with the style
attribute.
use dioxus::prelude::*;
use dioxus_web_component::{web_component, InjectedStyle};
#[web_component(
tag = "plop-greeting",
style = InjectedStyle::css(include_str!("./style.css"))
)]
fn Greeting(
// ...
) -> Element {
todo!()
}
The dioxus_web_component::InjectedStyle
could be raw CSS included in
an HTML <style>...</style>
element, or a link to an external stylesheet,
or a list of InjectedStyle
styles.
⚠️ WARNING: the web component is wrapped into an HTML div
with the dioxus
CSS class.
Component parameters
Every parameter of your component should be an attribute, a property, or an event. Note that a parameter could be both an attribute and a property.
The proc macro tries to detect the kind of parameter by looking at its type.
If the type starts by EventHandler
it is expected to be an event.
But, this kind of detection is not reliable, so you might need to add an annotation
to correct this behavior.
The annotations are also required if you need to customize the behavior.
Attributes
Attributes are like the href
of an <a>
HTML element.
You can enforce the parameter to be an attribute with the #[attribute]
annotation.
When the attribute value changes the dioxus component will be rendered.
The HTML value of an attribute is a String
, so you should be able
to parse that string into the target type.
Attribute name
The attribute name is by default the kebab-case of the parameter name.
You can choose another name with #[attribute(name = "my-custom-name")]
.
Attribute option
The attribute could be optional or not.
The proc macro tries to detect it automatically with the type name.
However the detection is not reliable, so you can use the #[attribute(option = true)]
to fix the detection if necessary.
Attribute initial
Attributes require to have an initial value. This value is used when no HTML attribute is provided, or if the attribute is removed.
By default, we expect the attribute type to implement std::default::Default
.
If it's not the case, or if you want to use another value for your attribute you
can provide your default expression with #[attribute(initial = String::from("World"))]
.
Note that Option<T>
implements Default
with the None
value
even if T
does not implement itself Default
.
Attribute parse
HTML attributes are strings and optional, so we need to convert the attribute value into the component parameter type.
The proc macro uses the std::str::parse
method. That means the target type
needs to implement the std::str::FromStr
trait.
In case of an error, the initial value (see below) is used.
If you want to change this behavior, you can provide your parsing expression.
If the parameter type is optional, the parse expression is used in this code:
let value = new_value.and_then(#parse);
.
If the type is NOT optional, the code looks like let value = new_value.and_then(#parse).unwrap_or_else(|| #initial);
.
The expected type for the parsing expression is FnOnce(String) -> Option<T>
.
The default expression is |value| value.parse().ok()
.
For example, if you have a parameter required
of type bool
and you want the value to be true
if the attribute is present whatever the content of the attribute, you could use #[attribute(parse = |s| !s.is_empty() )]
.
Property
On the Rust side of the code, properties work like attributes. The property is not accessible with pure HTML, you need Javascript to get/set the property.
Instead of the String
representation, you need to be able to convert the Rust type into a
Javascript type (here a wasm_bindgen::JsValue
).
For the setter, you need the opposite conversion.
Attribute name
The attribute name is by default the camelCase of the parameter name.
You can choose another name with #[property(name = "valueAsDate")]
.
Attribute readonly
If true
, it avoids setting the property from the javascript side.
By default getter and setter are generated.
Attribute initial
Properties require to have an initial value. This value is used when the component is initialized.
By default, we expect the property type to implement std::default::Default
.
If it's not the case, or if you want to use another value for your property you
can provide your default expression with #[property(initial = String::from("World"))]
.
Attribute try_into_js
For the getter, the property value should be converted to a wasm_bindgen::JsValue
.
By default, we use the std::convert::TryInto
implementation.
Note that there are many ways to implement TryInto<JsValue>
,
for example with impl TryFrom<T> for JsValue
or even impl From<T> for JsValue
.
See Rust TryInto
.
You can provide your custom conversion into the JsValue
with the try_into_js
attribute.
The expected type for the parsing expression is FnOnce(T) -> Result<JsValue, _>
.
Not that we do not care about the error type because
the error case is ignored and returns undefined
.
The default expression is |value| value.try_into()
.
Example to convert a custom type that wraps a bool
:
// ...
#[property(
try_into_js = |prop| {
let js_value = if prop.0 {
JsValue::TRUE
} else {
JsValue::FALSE
};
Ok::<_, Infallible>(js_value)
},
)]
prop2: MyProp,
// ...
#[derive(Clone, PartialEq, Default)]
struct MyProp(bool);
But in that situation, the recommended way is to implement From<MyProp> for JsValue
.
Attribute try_from_js
For the setter, the property value should be converted from a wasm_bindgen::JsValue
.
By default, we use the std::convert::TryInto
implementation.
Note that there are many ways to implement TryInto<T>
,
for example with impl TryFrom<JsValue> for T
or even impl From<JsValue> for T
.
See Rust TryInto
.
You can provide your custom conversion from the JsValue
with the try_from_js
attribute.
The expected type for the parsing expression is FnOnce(JsValue) -> Result<T, _>
.
Not that we do not care about the error type because
the error case is ignored.
The default expression is |value| value.try_into()
.
Example to convert a custom type that wraps a bool
:
// ...
#[property(
try_from_js= |value| Ok::<_, Infallible>(MyProp(value.is_truthy())),
)]
prop2: MyProp,
// ...
#[derive(Clone, PartialEq, Default)]
struct MyProp(bool);
But in that situation, the recommended way is to implement From<JsValue> for MyProp
.
Events
The web component could send custom events.
If the type of the component parameter is EventHandler
, the parameter is detected as an event.
Because this detection is not reliable, you could enforce a parameter to be
an event with the #[event]
annotation.
The custom event detail corresponds to the generic type of the Dioxus EventHandler
.
⚠️ IMPORTANT: The event type needs to implement Into<JsValue>
and be 'static
(does not have any reference).
You may need to implement it manually.
You could use serde-wasm-bindgen
, gloo_utils::format::JsValueSerdeExt
, wasm_bindgen::UnwrapThrowExt
to implement the Into<JsValue>
trait.
Event name
The HTML event name is detected from the parameter name by removing the on_
(or on
) prefix
and converting the name to kebab-case.
You can choose your value with the name
attribute like #[event(name = "build")]
to dispatch a build
event.
Event no_bubble
By default, the event bubbles up through the DOM.
You can avoid the bubbling with #[event(no_bubble = true)]
.
Event no_cancel
By default, the event is cancelable.
You can avoid the bubbling with #[event(no_cancel = true)]
.
Dependencies
~0.6–1MB
~24K SLoC