Struct Data

pub struct Data<'r> { /* private fields */ }

Type representing the body data of a request.

This type is the only means by which the body of a request can be retrieved. This type is not usually used directly. Instead, data guards (types that implement FromData) are created indirectly via code generation by specifying the data = "<var>" route parameter as follows:

#[post("/submit", data = "<var>")]
fn submit(var: DataGuard) { /* ... */ }

Above, DataGuard can be any type that implements FromData. Note that Data itself implements FromData.

Reading Data

Data may be read from a Data object by calling either the open() or peek() methods.

The open method consumes the Data object and returns the raw data stream. The Data object is consumed for safety reasons: consuming the object ensures that holding a Data object means that all of the data is available for reading.

The peek method returns a slice containing at most 512 bytes of buffered body data. This enables partially or fully reading from a Data object without consuming the Data object.

Implementations

impl<'r> Data<'r>

pub fn open(self, limit: ByteUnit) -> DataStream<'r>

Returns the raw data stream, limited to limit bytes.

The stream contains all of the data in the body of the request, including that in the peek buffer. The method consumes the Data instance. This ensures that a Data type always represents all of the data in a request.

Example

use rocket::data::{Data, ToByteUnit};

fn handler(data: Data<'_>) {
    let stream = data.open(2.mebibytes());
}

pub async fn peek(&mut self, num: usize) -> &[u8]

Fills the peek buffer with body data until it contains at least num bytes (capped to 512), or the complete body data, whichever is less, and returns it. If the buffer already contains either at least num bytes or all of the body data, no I/O is performed and the buffer is simply returned. If num is greater than 512, it is artificially capped to 512.

No guarantees are made about the actual size of the returned buffer except that it will not exceed the length of the body data. It may be:

• Less than num if num > 512 or the complete body data is < 512 or an error occurred while reading the body.
• Equal to num if num is <= 512 and exactly num bytes of the body data were successfully read.
• Greater than num if > num bytes of the body data have successfully been read, either by this request, a previous request, or opportunistically.

Data::peek_complete() can be used to determine if this buffer contains the complete body data.

Examples

In a data guard:

use rocket::request::{self, Request, FromRequest};
use rocket::data::{Data, FromData, Outcome};
use rocket::http::Status;

#[rocket::async_trait]
impl<'r> FromData<'r> for MyType {
    type Error = MyError;

    async fn from_data(r: &'r Request<'_>, mut data: Data<'r>) -> Outcome<'r, Self> {
        if data.peek(2).await != b"hi" {
            return Outcome::Forward((data, Status::BadRequest))
        }

        /* .. */
    }
}

In a fairing:

use rocket::{Rocket, Request, Data, Response};
use rocket::fairing::{Fairing, Info, Kind};

#[rocket::async_trait]
impl Fairing for MyType {
    fn info(&self) -> Info {
        Info {
            name: "Data Peeker",
            kind: Kind::Request
        }
    }

    async fn on_request(&self, req: &mut Request<'_>, data: &mut Data<'_>) {
        if data.peek(2).await == b"hi" {
            /* do something; body data starts with `"hi"` */
        }

        /* .. */
    }
}

pub fn peek_complete(&self) -> bool

Returns true if the peek buffer contains all of the data in the body of the request. Returns false if it does not or it is not known.

Example

use rocket::data::Data;

async fn handler(mut data: Data<'_>) {
    if data.peek_complete() {
        println!("All of the data: {:?}", data.peek(512).await);
    }
}

pub fn chain_transform<T>(&mut self, transform: T) -> &mut Self

where T: Transform + Send + Sync + 'static,

Chains the Transform transform to self.

Note that transforms do nothing until the data is open()ed and read.

pub fn chain_inspect<F>(&mut self, f: F) -> &mut Self

where F: FnMut(&[u8]) + Send + Sync + 'static,

Chain a Transform that can inspect the data as it streams.

pub fn chain_inplace_map<F>(&mut self, f: F) -> &mut Self

where F: FnMut(&mut TransformBuf<'_, '_>) + Send + Sync + 'static,

Chain a Transform that can in-place map the data as it streams. Unlike Data::chain_try_inplace_map(), this version assumes the mapper is infallible.

pub fn chain_try_inplace_map<F>(&mut self, f: F) -> &mut Self

where F: FnMut(&mut TransformBuf<'_, '_>) -> Result<()> + Send + Sync + 'static,

Chain a Transform that can in-place map the data as it streams. Unlike Data::chain_inplace_map(), this version allows the mapper to be infallible.

Trait Implementations

impl<'r> FromData<'r> for Data<'r>

type Error = Infallible

The associated error to be returned when the guard fails.

fn from_data<'life0, 'async_trait>( _: &'r Request<'life0>, data: Data<'r>, ) -> Pin<Box<dyn Future<Output = Outcome<'r, Self>> + Send + 'async_trait>>

where Self: 'async_trait, 'r: 'async_trait, 'life0: 'async_trait,

Asynchronously validates, parses, and converts an instance of Self from the incoming request body data.