Propel

Propel is a Blade-inspired templating system for Rocket.rs. You write views in Blade-style syntax, and Propel compiles each view into a typed Rust function when the app builds, so a template that uses a field the handler does not provide fails to build.

Documentation and a working example: propel.rocketboost.rs.

Install

Add the crates from crates.io. Propel 0.2 uses Rocket 0.5, and propel_rocket depends on Rocket 0.5.2 or newer in that series, so Cargo keeps one copy of Rocket:

[dependencies]
rocket = "0.5.2"
propel_rocket = "0.2.0"
propel_runtime = "0.2.0"
propel_macros = "0.2.0"
serde = { version = "1", features = ["derive"] }

[build-dependencies]
propel_compiler = "0.2.0"

propel_compiler is a build dependency: build.rs uses it to compile the views. propel_runtime provides Assets, and propel_macros provides #[derive(Truthy)]. serde is needed for the Serialize derive on the context structs.

Quick start

Put a view in resources/views/posts/index.propel:

@extends('layouts.app')

@section('content')
  @forelse ($posts as $post)
    <h2>{{ $post.title }}</h2>
  @empty
    <p>No posts yet.</p>
  @endforelse
@endsection

Compile it in build.rs:

fn main() {
    propel_compiler::build::Views::new("resources/views")
        .view("posts.index", "crate::views::PostsIndex")
        .build();
}

Define the context the view is rendered with, and render it from a route:

#[derive(serde::Serialize)]
pub struct PostsIndex {
    pub posts: Vec<Post>,
}

mod compiled {
    include!(concat!(env!("OUT_DIR"), "/propel_views.rs"));
}

#[get("/posts")]
fn posts() -> PropelView {
    let ctx = PostsIndex { posts: load_posts() };
    PropelView::from_result(compiled::posts::index::render(&ctx, &Assets::new("public")))
}

In a debug build, PropelView::render renders the same views from disk on every request, so an edit shows on refresh. A release build renders only the compiled views.

Features

• Blade-style syntax: {{ }} (escaped) and {!! !!} (raw), @if, @foreach, @forelse, @extends and @section, @yield, @include, @push and @stack, @vite and asset().
• Typed views: a missing field or a wrong type fails the build, with the template's file, line and column in the message.
• Assets: @vite and asset() read the Vite manifest, with the dev server while it runs. Packages can ship their own assets as a namespace.
• Namespaced views: a package registers its views as name::view, as Laravel's loadViewsFrom does.
• Escaping on by default: URLs in href, src and similar attributes are checked against an allowed list of schemes.

Crates

Crate	Purpose
propel_rocket	The PropelView responder, for Rocket
propel_compiler	Compiles views to Rust, through the build.rs helper
propel_macros	#[derive(Truthy)] and #[derive(PropelContext)]
propel_runtime	The renderer and the asset resolver
propel_parser	The template grammar and parser

Development

Run the tests and the lints from the repository root:

cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings
cargo fmt --all -- --check

The benchmark for the renderer is cargo bench -p propel_runtime.