Struct axum::Extension

source ·
pub struct Extension<T>(pub T);
Expand description

Extractor and response for extensions.

As extractor

This is commonly used to share state across handlers.

use axum::{
    Router,
    Extension,
    routing::get,
};
use std::sync::Arc;

// Some shared state used throughout our application
struct State {
    // ...
}

async fn handler(state: Extension<Arc<State>>) {
    // ...
}

let state = Arc::new(State { /* ... */ });

let app = Router::new().route("/", get(handler))
    // Add middleware that inserts the state into all incoming request's
    // extensions.
    .layer(Extension(state));

If the extension is missing it will reject the request with a 500 Internal Server Error response.

As response

Response extensions can be used to share state with middleware.

use axum::{
    Extension,
    response::IntoResponse,
};

async fn handler() -> (Extension<Foo>, &'static str) {
    (
        Extension(Foo("foo")),
        "Hello, World!"
    )
}

#[derive(Clone)]
struct Foo(&'static str);

Tuple Fields§

§0: T

Trait Implementations§

Returns a copy of the value. Read more
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The resulting type after dereferencing.
Dereferences the value.
If the extractor fails it’ll use this “rejection” type. A rejection is a kind of error that can be converted into a response. Read more
Perform the extraction.
Create a response.
The type returned in the event of an error. Read more
Set parts of the response
The wrapped service
Wrap the given service with the middleware, returning a new service that has been decorated with the middleware. Read more

Auto Trait Implementations§

Blanket Implementations§

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Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Converts to this type from a reference to the input type.
If the extractor fails it’ll use this “rejection” type. A rejection is a kind of error that can be converted into a response. Read more
Perform the extraction.
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Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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Should always be Self
The resulting type after obtaining ownership.
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The type returned in the event of a conversion error.
Performs the conversion.
The type returned in the event of a conversion error.
Performs the conversion.
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