CODEWITHSUNDEEP
rustrust-rocket
chenshuiluke
chenshuiluke

Reputation: 320

Can't return String from Rocket route

I'm trying to create a Rocket route that returns a string to the client, but I can't get it to work. So far, this is what I have:

#![feature(plugin)]
#![plugin(rocket_codegen)]
#[macro_use]

extern crate serde_derive;
extern crate toml;
extern crate rocket;

mod utilities;
mod pipeline_config;
mod assets;

use std::path::PathBuf;

#[get("/resources/<path..>")]
fn get_resource(path: PathBuf) -> Result<String, ()> {
    if let Some(page_path) = path.to_str() {
        match assets::get(&format!("{}/{}", "resources", page_path)) {
            Ok(page) => Ok(utf8_to_string(page)),
            Err(e) => Err(()),
        }
    }
    Err(())
}

fn main() {
    let rocket_obj = rocket::ignite();
    rocket_obj.mount("/", routes![get_resource]).launch();
}

pub fn utf8_to_string(bytes: &[u8]) -> String {
    let vector: Vec<u8> = Vec::from(bytes);
    String::from_utf8(vector).unwrap()
}

It looks like it should work, but it gives me an error expected (), found enum std::result::Result:

error[E0308]: mismatched types
  --> src/main.rs:18:9
   |
18 | /         match assets::get(&format!("{}/{}", "resources", page_path)) {
19 | |             Ok(page) => Ok(utf8_to_string(page)),
20 | |             Err(e) => Err(()),
21 | |         }
   | |         ^- help: try adding a semicolon: `;`
   | |_________|
   |           expected (), found enum `std::result::Result`
   |
   = note: expected type `()`
              found type `std::result::Result<std::string::String, ()>`

which makes no sense to me because I'm returning a Result with a String.

Upvotes: 0

Views: 496

Answers (1)

Boiethios
Boiethios

Reputation: 42849

When you use the functional-like style, see one function as one expression. Your function get_resource has two expressions put side by side. The compiler does not understand anything. You must put the alternative in an else branch, i.e.: if I could get some path, do this; else this is an error:

fn get_resource(path: PathBuf) -> Result<String, ()> { 
    if let Some(page_path) = path.to_str() {
        match assets::get(&format!("{}/{}", "resources", page_path)) {
            Ok(page) => Ok(utf8_to_string(page)),
            Err(e) => Err(()),
        }
    } else {
        Err(())
    }
}

In other words, you can see a function as a logic tree where each if or match block is a set of branches. The program will follow a path in this tree depending on the input: so you must have only one trunk, otherwise it does not make sense.

Upvotes: 3

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