Erst: Embedded Rust Templates

A tiny library for creating string templates, similar to ERB and JSP (angle-bracket-percent tags).

Precompiled along the lines of Askama.

Usage:

use erst::Template;

#[derive(Template)]
#[template(path = "simple.erst", type = "html")]
pub struct Container<'a> {
    pub collection: Vec<&'a str>,
}

fn main() {
    println!("{}", Container { collection: vec!["Hello", "<>", "World"] });
}

Where simple.erst looks like:

<div>
    <p>Hello!</p>
    <%
        let desc = format!("Here is your list of {} items:", self.collection.len());
    -%>
    <p><%= desc %></p>
    <ul>
        <% for x in &self.collection { -%>
            <li><%= x %></li>      
        <%- } %>
    </ul>
</div>

And then call it like:

ERST_TEMPLATES_DIR=/path/to/folder-containing-simple-erst cargo run

By default, the template's path will resolve to a file inside a templates directory in the current project context (i.e., CARGO_MANIFEST_DIR).

Note that, unlike Askama and other template systems, you need to reference any struct members with self. The template file is basically a function that takes &self (where self is the linked container object).

Currently, only the html type (or none) is supported, with very basic HTML escaping. To unescape HTML content in your template file, wrap the content in erst::Raw("<p>Hello</p>").

Dynamic

This library also provides a way to avoiding (re-)compiling the string-y parts of your template.

To enable this feature, add the following to your Cargo.toml:

[dependencies]
erst = { version = "0.2", features = ["dynamic"] }

[build-dependencies]
erst = { version = "0.2", features = ["dynamic"] }

And add a build.rs file with the following line:

fn main() {
    erst::shared::dynamic::rerun_if_templates_changed().unwrap();
}

And one more step:

cargo install erst-prepare

erst-prepare is a small binary that copies the code part of your templates to $XDG_CACHE_HOME so that the build script can re-run on changes only to the code part of your templates.

Then run your project like:

erst-prepare && cargo run

If you have a unique setup, you may need to use the --pkg-name and --templates-dir flags to erst-prepare:

erst-prepare --pkg-name my-project --templates-dir /path/to/your/templates/dir