Askama::Template Rocket response responder implement macro

askama-rocket-template-response-responder.rs

#[macro_use]

use askama_rocket::{Template};
use rocket::futures::executor::block_on;
use rocket::http::{ContentType, Status, Header};
use rocket::local::asynchronous::Client;
use std::io::Cursor;

pub use askama::*;
pub use rocket::request::Request;
use rocket::response::Response;
pub use rocket::response::{Responder, Result};

/// # template_responder
///
/// Askama::Template Rocket response responder implement macro
///
///
/// # Arguments
///
/// * `ident`: Template structure
///
/// # Examples
///
/// ```
///     template_responder!(Index);        // Impl rocket Response Responder for Index
///     #[derive(Template)]                // Template parser/builder trait
///     #[template(path = "index.html")]   // template name
///     pub struct Index<'a> {
///         pub title: &'a str,
///     }
/// 
///     ...
///     
///     #[get("/")]
///     pub fn index() -> Index<'static> {
///         Index { title: "Index",}
///     }
/// ```
macro_rules! impl_template_responder {
    ($t:ident) => {
        impl <'r>Responder<'r, 'r> for $t<'_> {
            fn respond_to<'o>(self, _: &'r Request<'_>) -> Result<'static> {
                respond(&self)
            }
        }
    }
}

impl_template_responder!(Index);
#[derive(Template)]
#[template(path = "index.html")]
pub struct Index<'a> {
    pub title: &'a str,
}

// got from there: askama_rocket::respond
// unfortunately it's impossible to implement existed one...
fn respond<T: Template>(t: &T) -> Result<'static> {
    let rsp = t.render().map_err(|_| Status::InternalServerError)?;
    Response::build()
        .header(Header::new("content-type", T::MIME_TYPE))
        .sized_body(rsp.len(), Cursor::new(rsp))
        .ok()
}