Document differences between DefaultBodyLimit and RequestBodyLimit (#1461)

* Document differences between `DefaultBodyLimit` and `RequestBodyLimit`

* fix grammar

* fix accidental force push
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David Pedersen 2022-10-10 17:43:05 +02:00 committed by GitHub
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@ -11,10 +11,65 @@ use tower_layer::Layer;
/// Note that if an extractor consumes the body directly with [`Body::data`], 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.
///
/// `DefaultBodyLimit` is also easier to integrate into an existing setup since it doesn't change
/// the request body type:
///
/// ```
/// use axum::{
/// Router,
/// routing::post,
/// body::Body,
/// extract::{DefaultBodyLimit, RawBody},
/// http::Request,
/// };
///
/// let router = Router::new()
/// .route(
/// "/",
/// // even with `DefaultBodyLimit` the request body is still just `Body`
/// post(|request: Request<Body>| async {}),
/// )
/// .layer(DefaultBodyLimit::max(1024));
/// ```
///
/// ```
/// use axum::{Router, routing::post, body::Body, extract::RawBody, http::Request};
/// use tower_http::limit::RequestBodyLimitLayer;
/// use http_body::Limited;
///
/// let router = Router::new()
/// .route(
/// "/",
/// // `RequestBodyLimitLayer` changes the request body type to `Limited<Body>`
/// // extracting a different body type wont work
/// post(|request: Request<Limited<Body>>| async {}),
/// )
/// .layer(RequestBodyLimitLayer::new(1024));
/// ```
///
/// In general using `DefaultBodyLimit` is recommended but if you need to use third party
/// extractors and want to sure a limit is also applied there then [`RequestBodyLimit`] should be
/// used.
///
/// [`Body::data`]: http_body::Body::data
/// [`Bytes`]: bytes::Bytes
/// [`Json`]: https://docs.rs/axum/0.6.0-rc.2/axum/struct.Json.html
/// [`Form`]: https://docs.rs/axum/0.6.0-rc.2/axum/struct.Form.html
/// [`FromRequest`]: crate::extract::FromRequest
/// [`RequestBodyLimit`]: https://docs.rs/tower-http/latest/tower_http/limit/struct.RequestBodyLimit.html
/// [`RequestExt::with_limited_body`]: crate::RequestExt::with_limited_body
/// [`RequestExt::into_limited_body`]: crate::RequestExt::into_limited_body
#[derive(Debug, Clone)]
pub struct DefaultBodyLimit {
kind: DefaultBodyLimitKind,