Allow using Template::custom without template_dir

[cubetastic33]

Description

I want to compile my rocket program into a single binary, so that it is easier to distribute. Since I use tera templates, I tried using Templates::custom so that I can add the templates with include_str! during compile time. Following this example, I was able to get the template working from a string, but it would not run unless template_dir existed. It works even if I create an empty templates directory. I think this shouldn't be a requirement unless external template files are being used, and now I'm unable to make the standalone binary work.

To Reproduce

#[macro_use] extern crate rocket;

use rocket_dyn_templates::{Template, tera::Tera};
use std::collections::HashMap;

#[get("/")]
fn index() -> Template {
    let mut context: HashMap<String, String> = HashMap::new();
    context.insert("foo".to_string(), "bar".to_string());
    Template::render("index.html", context)
}

pub fn customize(tera: &mut Tera) {
    tera.add_raw_template("index.html", "{{ foo }}").expect("valid Tera template");
}

#[launch]
fn rocket() -> _ {
    rocket::build()
        .mount("/", routes![index])
        .attach(Template::custom(|engines| customize(&mut engines.tera)))
}

Expected Behavior

The code would run without a templates directory because I'm not using any external templates

Environment:

• OS Distribution and Kernel: Artix Linux, 5.13.12-artix1-1
• Rocket Version: 0.5.0-rc.1

Additional Context

I tried setting template_dir to ., which is a kinda hacky solution but worked. But that seems to be a runtime config setting, so I wasn't able to use it to make the single file binary.

[SergioBenitez]

This looks to be exactly #1792. Is that right?

[cubetastic33]

Yes, you're right - my bad. Do you know if there's been any progress with the implementation?