Struct axum_core::extract::DefaultBodyLimit

pub struct DefaultBodyLimit { /* private fields */ }

Layer for configuring the default request body limit.

For security reasons, Bytes will, by default, not accept bodies larger than 2MB. This also applies to extractors that uses Bytes internally such as String, Json, and Form.

This middleware provides ways to configure that.

Note that if an extractor consumes the body directly with Body::poll_frame, or similar, the default limit is not applied.

Difference between DefaultBodyLimit and RequestBodyLimit

DefaultBodyLimit and RequestBodyLimit serve similar functions but in different ways.

DefaultBodyLimit is local in that it only applies to FromRequest implementations that explicitly apply it (or call another extractor that does). You can apply the limit with RequestExt::with_limited_body or RequestExt::into_limited_body

RequestBodyLimit is applied globally to all requests, regardless of which extractors are used or how the body is consumed.

Example

use axum::{
    Router,
    routing::post,
    body::Body,
    extract::{Request, DefaultBodyLimit},
};

let app = Router::new()
    .route("/", post(|request: Request| async {}))
    // change the default limit
    .layer(DefaultBodyLimit::max(1024));

In general using DefaultBodyLimit is recommended but if you need to use third party extractors and want to make sure a limit is also applied there then RequestBodyLimit should be used.

Different limits for different routes

DefaultBodyLimit can also be selectively applied to have different limits for different routes:

use axum::{
    Router,
    routing::post,
    body::Body,
    extract::{Request, DefaultBodyLimit},
};

let app = Router::new()
    // this route has a different limit
    .route("/", post(|request: Request| async {}).layer(DefaultBodyLimit::max(1024)))
    // this route still has the default limit
    .route("/foo", post(|request: Request| async {}));

Implementations

impl DefaultBodyLimit

pub fn disable() -> Self

Disable the default request body limit.

This must be used to receive bodies larger than the default limit of 2MB using Bytes or an extractor built on it such as String, Json, Form.

Note that if you’re accepting data from untrusted remotes it is recommend to add your own limit such as [tower_http::limit].

Example

use axum::{
    Router,
    routing::get,
    body::{Bytes, Body},
    extract::DefaultBodyLimit,
};
use tower_http::limit::RequestBodyLimitLayer;
use http_body_util::Limited;

let app: Router<()> = Router::new()
    .route("/", get(|body: Bytes| async {}))
    // Disable the default limit
    .layer(DefaultBodyLimit::disable())
    // Set a different limit
    .layer(RequestBodyLimitLayer::new(10 * 1000 * 1000));

pub fn max(limit: usize) -> Self

Set the default request body limit.

By default the limit of request body sizes that Bytes::from_request (and other extractors built on top of it such as String, Json, and Form) is 2MB. This method can be used to change that limit.

Example

use axum::{
    Router,
    routing::get,
    body::{Bytes, Body},
    extract::DefaultBodyLimit,
};
use tower_http::limit::RequestBodyLimitLayer;
use http_body_util::Limited;

let app: Router<()> = Router::new()
    .route("/", get(|body: Bytes| async {}))
    // Replace the default of 2MB with 1024 bytes.
    .layer(DefaultBodyLimit::max(1024));

Trait Implementations

impl Clone for DefaultBodyLimit

fn clone(&self) -> DefaultBodyLimit

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for DefaultBodyLimit

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

Formats the value using the given formatter.

impl<S> Layer<S> for DefaultBodyLimit

type Service = DefaultBodyLimitService<S>

The wrapped service

fn layer(&self, inner: S) -> Self::Service

Wrap the given service with the middleware, returning a new service that has been decorated with the middleware.