Router
Routers in Single Page Applications (SPA) handle displaying different pages depending on what the URL is. Instead of the default behavior of requesting a different remote resource when a link is clicked, the router instead sets the URL locally to point to a valid route in your application. The router then detects this change and then decides what to render.
Yew provides router support in the yew-router
crate. To start using it, add the dependency to your Cargo.toml
yew-router = { git = "https://github.com/yewstack/yew.git" }
The utilities needed are provided under yew_router::prelude
,
Usage
You start by defining a Route
.
Routes are defined as an enum
which derives Routable
. This enum must be Clone + PartialEq
.
use yew_router::prelude::*;
#[derive(Clone, Routable, PartialEq)]
enum Route {
#[at("/")]
Home,
#[at("/secure")]
Secure,
#[not_found]
#[at("/404")]
NotFound,
}
A Route
is paired with a <Switch />
component, which finds the variant whose path matches the browser's
current URL and passes it to the render
callback. The callback then decides what to render. In case no path is
matched, the router navigates to the path with not_found
attribute. If no route is specified, nothing is rendered, and
a message is logged to the console stating that no route was matched.
Most of yew-router's components, in particular <Link />
and <Switch />
, must be (grand-)children of one of the Router components
(e.g. <BrowserRouter />
). You usually only need a single Router in your app, most often rendered immediately by your most top-level <App />
component. The Router registers a context, which is needed for Links and Switches to function. An example is shown below.
When using yew-router
in a browser environment, <BrowserRouter />
is highly recommended.
You can find other router flavors in the API Reference.
use yew_router::prelude::*;
use yew::prelude::*;
#[derive(Clone, Routable, PartialEq)]
enum Route {
#[at("/")]
Home,
#[at("/secure")]
Secure,
#[not_found]
#[at("/404")]
NotFound,
}
#[function_component(Secure)]
fn secure() -> Html {
let navigator = use_navigator().unwrap();
let onclick = Callback::from(move |_| navigator.push(&Route::Home));
html! {
<div>
<h1>{ "Secure" }</h1>
<button {onclick}>{ "Go Home" }</button>
</div>
}
}
fn switch(routes: Route) -> Html {
match routes {
Route::Home => html! { <h1>{ "Home" }</h1> },
Route::Secure => html! {
<Secure />
},
Route::NotFound => html! { <h1>{ "404" }</h1> },
}
}
#[function_component(Main)]
fn app() -> Html {
html! {
<BrowserRouter>
<Switch<Route> render={switch} /> // <- must be child of <BrowserRouter>
</BrowserRouter>
}
}
Path Segments
It is also possible to extract information from a route using dynamic and named wildcard segments.
You can then access the post's id inside <Switch />
and forward it to the appropriate component via properties.
use yew::prelude::*;
use yew_router::prelude::*;
#[derive(Clone, Routable, PartialEq)]
enum Route {
#[at("/")]
Home,
#[at("/post/:id")]
Post { id: String },
#[at("/*path")]
Misc { path: String },
}
fn switch(route: Route) -> Html {
match route {
Route::Home => html! { <h1>{ "Home" }</h1> },
Route::Post { id } => html! {<p>{format!("You are looking at Post {}", id)}</p>},
Route::Misc { path } => html! {<p>{format!("Matched some other path: {}", path)}</p>},
}
}
You can have a normal Post
variant instead of Post {id: String}
too. For example, when Post
is rendered
with another router, the field can then be redundant as the other router can match and handle the path. See the
Nested Router section below for details
Note the fields must implement Clone + PartialEq
as part of the Route
enum. They must also implement
std::fmt::Display
and std::str::FromStr
for serialization and deserialization. Primitive types like integer, float,
and String already satisfy the requirements.
In case when the form of the path matches, but the deserialization fails (as per FromStr
). The router will consider
the route as unmatched and try to render the not found route (or a blank page if the not found route is unspecified).
Consider this example:
#[derive(Clone, Routable, PartialEq)]
enum Route {
#[at("/news/:id")]
News { id: u8 },
#[not_found]
#[at("/404")]
NotFound,
}
// switch function renders News and id as is. Omitted here.
When the segment goes over 255, u8::from_str()
fails with ParseIntError
, the router will then consider the route
unmatched.
For more information about the route syntax and how to bind parameters, check out route-recognizer.
Location
The router provides a universal Location
struct via context which can be used to access routing information.
They can be retrieved by hooks or convenient functions on ctx.link()
.
Navigation
yew_router
provides a handful of tools to work with navigation.
Link
A <Link />
renders as an <a>
element, the onclick
event handler will call
preventDefault, and push the targeted page to the
history and render the desired page, which is what should be expected from a Single Page App. The default onclick
of a
normal anchor element would reload the page.
The <Link />
component also passes its children to the <a>
element. Consider it a replacement of <a/>
for in-app
routes. Except you supply a to
attribute instead of a href
. An example usage:
<Link<Route> to={Route::Home}>{ "click here to go home" }</Link<Route>>
Struct variants work as expected too:
<Link<Route> to={Route::Post { id: "new-yew-release".to_string() }}>{ "Yew v0.19 out now!" }</Link<Route>>
Navigator API
Navigator API is provided for both function components and struct components. They enable callbacks to change the
route. A Navigator
instance can be obtained in either case to manipulate the route.
Function Components
For function components, the use_navigator
hook re-renders the component when the underlying navigator provider changes.
Here is how to implement a button that navigates to the Home
route when clicked.
#[function_component(MyComponent)]
pub fn my_component() -> Html {
let navigator = use_navigator().unwrap();
let onclick = Callback::from(move |_| navigator.push(&Route::Home));
html! {
<>
<button {onclick}>{"Click to go home"}</button>
</>
}
}
The example here uses Callback::from
. Use a normal callback if the target route can be the same as the route
the component is in, or just to play safe. For example, consider a logo button on every page that goes back to the
home page when clicked. Clicking that button twice on the home page causes the code to panic because the second click pushes an
identical Home route and the use_navigator
hook will not trigger a re-render.
If you want to replace the current location instead of pushing a new location onto the stack, use navigator.replace()
instead of navigator.push()
.
You may notice navigator
has to move into the callback, so it cannot be used again for other callbacks. Luckily navigator
implements Clone
, here is for example how to have multiple buttons for different routes:
use yew::prelude::*;
use yew_router::prelude::*;
#[function_component(NavItems)]
pub fn nav_items() -> Html {
let navigator = use_navigator().unwrap();
let go_home_button = {
let navigator = navigator.clone();
let onclick = Callback::from(move |_| navigator.push(&Route::Home));
html! {
<button {onclick}>{"click to go home"}</button>
}
};
let go_to_first_post_button = {
let navigator = navigator.clone();
let onclick = Callback::from(move |_| navigator.push(&Route::Post { id: "first-post".to_string() }));
html! {
<button {onclick}>{"click to go the first post"}</button>
}
};
let go_to_secure_button = {
let onclick = Callback::from(move |_| navigator.push(&Route::Secure));
html! {
<button {onclick}>{"click to go to secure"}</button>
}
};
html! {
<>
{go_home_button}
{go_to_first_post_button}
{go_to_secure_button}
</>
}
}
Struct Components
For struct components, the Navigator
instance can be obtained through the ctx.link().navigator()
API. The rest is
identical to the function component case. Here is an example of a view function that renders a single button.
fn view(&self, ctx: &Context<Self>) -> Html {
let navigator = ctx.link().navigator().unwrap();
let onclick = Callback::from(move |_| navigator.push(&MainRoute::Home));
html!{
<button {onclick}>{"Go Home"}</button>
}
}
Redirect
yew-router
also provides a <Redirect />
component in the prelude. It can be used to achieve similar effects as the
navigator API. The component accepts a
to
attribute as the target route. When a <Redirect/>
is rendered users will be redirected to the route specified in props.
Here is an example:
#[function_component(SomePage)]
fn some_page() -> Html {
// made-up hook `use_user`
let user = match use_user() {
Some(user) => user,
// Redirects to the login page when user is `None`.
None => return html! {
<Redirect<Route> to={Route::Login}/>
},
};
// ... actual page content.
}
Redirect
vs Navigator
, which to useThe Navigator API is the only way to manipulate route in callbacks.
While <Redirect />
can be used as return values in a component. You might also want to use <Redirect />
in another
non-component context, for example in the switch function of a Nested Router.
Listening to Changes
Function Components
You can use use_location
and use_route
hooks. Your components will re-render when
provided values change.
Struct Components
In order to react on route changes, you can pass a callback closure to the add_location_listener()
method of ctx.link()
.
The location listener will get unregistered once it is dropped. Make sure to store the handle inside your component state.
fn create(ctx: &Context<Self>) -> Self {
let listener = ctx.link()
.add_location_listener(ctx.link().callback(
// handle event
))
.unwrap();
MyComponent {
_listener: listener
}
}
ctx.link().location()
and ctx.link().route::<R>()
can also be used to retrieve the location and the route once.
Query Parameters
Specifying query parameters when navigating
In order to specify query parameters when navigating to a new route, use either navigator.push_with_query
or
the navigator.replace_with_query
functions. It uses serde
to serialize the parameters into a query string for the URL so
any type that implements Serialize
can be passed. In its simplest form, this is just a HashMap
containing string
pairs.
Obtaining query parameters for the current route
location.query
is used to obtain the query parameters. It uses serde
to deserialize the parameters from the query string
in the URL.
Nested Router
Nested router can be useful when the app grows larger. Consider the following router structure:
The nested SettingsRouter
handles all URLs that start with /settings
. Additionally, it redirects URLs that are not
matched to the main NotFound
route. So /settings/gibberish
will redirect to /404
.
Though note that this is still a work in progress so the way we do this is not final
It can be implemented with the following code:
use yew::prelude::*;
use yew_router::prelude::*;
use gloo::utils::window;
use wasm_bindgen::UnwrapThrowExt;
#[derive(Clone, Routable, PartialEq)]
enum MainRoute {
#[at("/")]
Home,
#[at("/news")]
News,
#[at("/contact")]
Contact,
#[at("/settings")]
SettingsRoot,
#[at("/settings/*")]
Settings,
#[not_found]
#[at("/404")]
NotFound,
}
#[derive(Clone, Routable, PartialEq)]
enum SettingsRoute {
#[at("/settings")]
Profile,
#[at("/settings/friends")]
Friends,
#[at("/settings/theme")]
Theme,
#[not_found]
#[at("/settings/404")]
NotFound,
}
fn switch_main(route: MainRoute) -> Html {
match route {
MainRoute::Home => html! {<h1>{"Home"}</h1>},
MainRoute::News => html! {<h1>{"News"}</h1>},
MainRoute::Contact => html! {<h1>{"Contact"}</h1>},
MainRoute::SettingsRoot | MainRoute::Settings => html! { <Switch<SettingsRoute> render={switch_settings} /> },
MainRoute::NotFound => html! {<h1>{"Not Found"}</h1>},
}
}
fn switch_settings(route: SettingsRoute) -> Html {
match route {
SettingsRoute::Profile => html! {<h1>{"Profile"}</h1>},
SettingsRoute::Friends => html! {<h1>{"Friends"}</h1>},
SettingsRoute::Theme => html! {<h1>{"Theme"}</h1>},
SettingsRoute::NotFound => html! {<Redirect<MainRoute> to={MainRoute::NotFound}/>}
}
}
#[function_component(App)]
pub fn app() -> Html {
html! {
<BrowserRouter>
<Switch<MainRoute> render={switch_main} />
</BrowserRouter>
}
}
Basename
It's possible to define a basename with yew-router
.
A basename is a common prefix of all routes. Both the Navigator API and
<Switch />
component respect basename setting. All pushed routes will be
prefixed with the basename and all switches will strip the basename before
trying to parse the path into a Routable
.
If a basename prop is not supplied to the Router component, it will use
the href attribute of the <base />
element in your HTML file and
fallback to /
if no <base />
is present in the HTML file.