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Struct actix_web::web::Data[][src]

pub struct Data<T: ?Sized>(_);
Expand description

Application data.

Application level data is a piece of arbitrary data attached to the app, scope, or resource. Application data is available to all routes and can be added during the application configuration process via App::data().

Application data can be accessed by using Data<T> extractor where T is data type.

Note: HTTP server accepts an application factory rather than an application instance. HTTP server constructs an application instance for each thread, thus application data must be constructed multiple times. If you want to share data between different threads, a shareable object should be used, e.g. Send + Sync. Application data does not need to be Send or Sync. Internally Data contains an Arc.

If route data is not set for a handler, using Data<T> extractor would cause a 500 Internal Server Error response.

Unsized Data

For types that are unsized, most commonly dyn T, Data can wrap these types by first constructing an Arc<dyn T> and using the From implementation to convert it.

let displayable_arc: Arc<dyn Display> = Arc::new(42usize);
let displayable_data: Data<dyn Display> = Data::from(displayable_arc);

Examples

use std::sync::Mutex;
use actix_web::{App, HttpRequest, HttpResponse, Responder, web::{self, Data}};

struct MyData {
    counter: usize,
}

/// Use the `Data<T>` extractor to access data in a handler.
async fn index(data: Data<Mutex<MyData>>) -> impl Responder {
    let mut my_data = data.lock().unwrap();
    my_data.counter += 1;
    HttpResponse::Ok()
}

/// Alteratively, use the `HttpRequest::app_data` method to access data in a handler.
async fn index_alt(req: HttpRequest) -> impl Responder {
    let data = req.app_data::<Data<Mutex<MyData>>>().unwrap();
    let mut my_data = data.lock().unwrap();
    my_data.counter += 1;
    HttpResponse::Ok()
}

let data = Data::new(Mutex::new(MyData { counter: 0 }));

let app = App::new()
    // Store `MyData` in application storage.
    .app_data(Data::clone(&data))
    .route("/index.html", web::get().to(index))
    .route("/index-alt.html", web::get().to(index_alt));

Implementations

Create new Data instance.

Get reference to inner app data.

Convert to the internal Arc

Trait Implementations

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

Formats the value using the given formatter. Read more

The resulting type after dereferencing.

Dereferences the value.

Performs the conversion.

The associated error which can be returned.

Future that resolves to a Self.

Create a Self from request parts asynchronously.

Create a Self from request head asynchronously. Read more

Serialize this value into the given Serde serializer. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Performs the conversion.

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

Performs the conversion.

Should always be Self

The resulting type after obtaining ownership.

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into)

Uses borrowed data to replace owned data, usually by cloning. Read more

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.

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more