pub trait FromDataSimple: Sized {
type Error;
// Required method
fn from_data(
request: &Request<'_>,
data: Data,
) -> Outcome<Self, Self::Error>;
}Expand description
A simple, less complex variant of FromData.
When transformation of incoming data isn’t required, data guards should
implement this trait instead of FromData. Any type that implements
FromDataSimple automatically implements FromData. For a description of
data guards, see the FromData documentation.
§Example
Say that you have a custom type, Person:
struct Person {
name: String,
age: u16
}Person has a custom serialization format, so the built-in Json type
doesn’t suffice. The format is <name>:<age> with Content-Type: application/x-person. You’d like to use Person as a FromData type so
that you can retrieve it directly from a client’s request body:
#[post("/person", data = "<person>")]
fn person(person: Person) -> &'static str {
"Saved the new person to the database!"
}A FromDataSimple implementation allowing this looks like:
use std::io::Read;
use rocket::{Request, Data, Outcome, Outcome::*};
use rocket::data::{self, FromDataSimple};
use rocket::http::{Status, ContentType};
// Always use a limit to prevent DoS attacks.
const LIMIT: u64 = 256;
impl FromDataSimple for Person {
type Error = String;
fn from_data(req: &Request, data: Data) -> data::Outcome<Self, String> {
// Ensure the content type is correct before opening the data.
let person_ct = ContentType::new("application", "x-person");
if req.content_type() != Some(&person_ct) {
return Outcome::Forward(data);
}
// Read the data into a String.
let mut string = String::new();
if let Err(e) = data.open().take(LIMIT).read_to_string(&mut string) {
return Failure((Status::InternalServerError, format!("{:?}", e)));
}
// Split the string into two pieces at ':'.
let (name, age) = match string.find(':') {
Some(i) => (string[..i].to_string(), &string[(i + 1)..]),
None => return Failure((Status::UnprocessableEntity, "':'".into()))
};
// Parse the age.
let age: u16 = match age.parse() {
Ok(age) => age,
Err(_) => return Failure((Status::UnprocessableEntity, "Age".into()))
};
// Return successfully.
Success(Person { name, age })
}
}Required Associated Types§
Required Methods§
Sourcefn from_data(request: &Request<'_>, data: Data) -> Outcome<Self, Self::Error>
fn from_data(request: &Request<'_>, data: Data) -> Outcome<Self, Self::Error>
Validates, parses, and converts an instance of Self from the incoming
request body data.
If validation and parsing succeeds, an outcome of Success is returned.
If the data is not appropriate given the type of Self, Forward is
returned. If parsing fails, Failure is returned.
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.