Struct actix_web::web::Data

pub struct Data<T: ?Sized>(_);

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

impl<T> Data<T>

pub fn new(state: T) -> Data<T>

Create new Data instance.

impl<T: ?Sized> Data<T>

pub fn get_ref(&self) -> &T

Get reference to inner app data.

pub fn into_inner(self) -> Arc<T>

Convert to the internal Arc

Trait Implementations

impl<T: ?Sized> Clone for Data<T>

fn clone(&self) -> Data<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug + ?Sized> Debug for Data<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: ?Sized> Deref for Data<T>

type Target = Arc<T>

The resulting type after dereferencing.

fn deref(&self) -> &Arc<T>

Dereferences the value.

impl<T: ?Sized> From<Arc<T>> for Data<T>

fn from(arc: Arc<T>) -> Self

Converts to this type from the input type.

impl<T: ?Sized + 'static> FromRequest for Data<T>

type Error = Error

The associated error which can be returned.

type Future = Ready<Result<Data<T>, Error>>

Future that resolves to a Self.

fn from_request(req: &HttpRequest, _: &mut Payload) -> Self::Future

Create a Self from request parts asynchronously.

fn extract(req: &HttpRequest) -> Self::Future

Create a Self from request head asynchronously.

impl<T> Serialize for Data<T> where
    T: Serialize, 

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where
    S: Serializer, 

Serialize this value into the given Serde serializer.