pub trait FromRequest<S, B, M = ViaRequest>: Sized {
type Rejection: IntoResponse;
// Required method
fn from_request<'life0, 'async_trait>(
req: Request<B>,
state: &'life0 S,
) -> Pin<Box<dyn Future<Output = Result<Self, Self::Rejection>> + Send + 'async_trait>>
where 'life0: 'async_trait,
Self: 'async_trait;
}Expand description
Types that can be created from requests.
Extractors that implement FromRequest can consume the request body and can thus only be run
once for handlers.
If your extractor doesn’t need to consume the request body then you should implement
FromRequestParts and not FromRequest.
See axum::extract for more general docs about extractors.
§What is the B type parameter?
FromRequest is generic over the request body (the B in
http::Request<B>). This is to allow FromRequest to be usable with any
type of request body. This is necessary because some middleware change the
request body, for example to add timeouts.
If you’re writing your own FromRequest that wont be used outside your
application, and not using any middleware that changes the request body, you
can most likely use axum::body::Body.
If you’re writing a library that’s intended for others to use, it’s recommended to keep the generic type parameter:
use axum::{
async_trait,
extract::FromRequest,
http::{self, Request},
};
struct MyExtractor;
#[async_trait]
impl<S, B> FromRequest<S, B> for MyExtractor
where
// these bounds are required by `async_trait`
B: Send + 'static,
S: Send + Sync,
{
type Rejection = http::StatusCode;
async fn from_request(req: Request<B>, state: &S) -> Result<Self, Self::Rejection> {
// ...
}
}This ensures your extractor is as flexible as possible.
Required Associated Types§
Sourcetype Rejection: IntoResponse
type Rejection: IntoResponse
If the extractor fails it’ll use this “rejection” type. A rejection is a kind of error that can be converted into a response.
Required Methods§
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.