Crate yew_nested_router

A router for Yew, supporting nesting.

Usage

The nested router makes use of Yew’s context features. It injects a routing context, tied to a type implementing the target::Target trait. It then is possible to scope/translate between levels.

Targets

“Targets” are the route targets, things the page can point to. They must be an enum, implementing the target::Target trait. This can easily be done using the Target derive:

#[derive(Clone, Debug, PartialEq, Eq, Target)]
pub enum AppRoute {
  #[target(index)]
  Index,
  Foo,
  Bar,
}

This created a target enum with three paths (/, /foo, /bar).

Main router

Each application needs a main entry point for the router (Router). This simply injects the routing context, and provides the necessary information internally. All children of the component will simply be rendered.

#[function_component(MyApp)]
pub fn my_app() -> Html {
  html!(
    <Router<AppRoute>>
      <MyContent/>
    </Router<AppRoute>>
  )
}

Switching content

Having the route context available, allows to switch based on its state. This is done using the Switch component, which searches (upwards) for a matching routing context (of the target type).

#[function_component(MyContent)]
pub fn my_content() -> Html {
  html!(
    <Switch<AppRoute> render={|target|match target {
      AppRoute::Index => html!(<Index/>),
      AppRoute::Foo => html!(<Foo/>),
      AppRoute::Bar => html!(<Bar/>),
    }}/>
  )
}

The Switch component does not have any children, as its content is evaluated from the render callback.

If no target matched, then none of the switches will match either. If is possible to define a default target on the router.

Nesting

When nesting, first the structure must be declared. Let’s adapt the example from above:

#[derive(Clone, Debug, PartialEq, Eq, Target)]
pub enum AppRoute {
  #[target(index)]
  Index,
  Foo(#[target(default)] Details),
  Bar {
    id: String,
    #[target(nested, default)]
    details: Details,
  },
}

#[derive(Clone, Debug, PartialEq, Eq, Target)]
pub enum Details {
  Overview,
  Code,
  Metrics,
}

impl Default for Details {
  fn default() -> Self {
    Self::Overview
  }
}

This changed the following:

• It added a nested layer to Foo, which by default will use the Details::Overview target.
• It added a nested layer to Bar
  • Capturing a path variable into id
  • Then using a nested layer to Details, again using the default target.

This will process the following routes

Path	Target
/	AppRoute::Index
/foo, /foo/overview	AppRoute::Foo({id}::Overview)
/foo/code	AppRoute::Foo(Details::Code)
/foo/metrics	AppRoute::Foo({id}::Metrics)
/bar	no match
/bar/{id}, /foo/{id}/overview	AppRoute::Bar {id: "id", details: Details::Overview}
/foo/{id}/code	AppRoute::Bar {id: "id", details: Details::Code}
/foo/{id}/metrics	AppRoute::Bar {id: "id", details: Details::Metrics}

Scoping/Translating

The main router will only insert an routing context for the AppRoutes context. Now we need to translate down the next level. This is done using the Scope component, which translates “from” -> “to”, or Parent -> Child.

#[function_component(Foo)]
pub fn foo() -> Html {
  html! (
    <Scope<AppRoute, Details> mapper={AppRoute::mapper_foo}>
      <Switch<Details> render={|target|html!(/* ... */)}/>
    </Scope<AppRoute, Details>>
  )
}

The AppRoute::mapper_foo function was automatically created by the Target derive. It translates upwards and downwards between the two levels.

NOTE: Targets having additional information do not get a mapper automatically created, as that information might not be known on the lower levels. In these cases you will have to implement the mapper yourself. An example is provided for the target Page::D in the examples folder.

For a more complete example on nesting, see the full example in the examples folder.

Navigating

There is an out-of-the-box component named components::Link, which allows to navigate to a target. It is also possible to achieve the same, using the routing context, which can be acquired using prelude::use_router.

use yew_nested_router::components::Link;

#[function_component(MyContent)]
pub fn my_content() -> Html {
  html!(
    <>
      <ul>
        <li><Link<AppRoute> target={AppRoute::Index}>{"Index"}</Link<AppRoute>></li>
        <li><Link<AppRoute> target={AppRoute::Foo(Details::Overview)}>{"Foo"}</Link<AppRoute>></li>
        <li><Link<AppRoute> target={AppRoute::Bar{ id: "".into(), details: Details::Overview}}>{"Bar"}</Link<AppRoute>></li>
      </ul>
      <Switch<AppRoute> render={|target|match target {
        AppRoute::Index => html!(<Index/>),
        AppRoute::Foo(_) => html!(<Foo/>),
        AppRoute::Bar{..} => html!(<Bar/>),
      }}/>
    </>
  )
}

Interoperability

This implementation makes use of the browser’s history API. While it is possible to receive the current state from the History API, and trigger “back” operations, using web_sys::History::push_state directly will not trigger an event and thus no render a different page.

As gloo_history creates its internal type and state system, it is not interoperable with this crate. It still is possible to use gloo_utils::history though, which is just a shortcut of getting web_sys::History.

More examples

See the examples folder.

Modules

• components
  Some out-of-the box components.
• prelude
  Common includes.
• target
  Routing target

Structs

• History
• Router
  Top-level router component.
• Scope
  A component, translating down to the next level.
• Switch
  A component two switch rendering between the different targets.

Derive Macros

• Target
  Helps implementing the Target trait in an enum.