rocket_dyn_templates/engine/
minijinja.rs

1use std::sync::Arc;
2use std::path::Path;
3use std::collections::HashMap;
4
5use rocket::serde::Serialize;
6use minijinja::{Environment, Error, ErrorKind, AutoEscape};
7
8use crate::engine::Engine;
9
10impl Engine for Environment<'static> {
11    const EXT: &'static str = "j2";
12
13    fn init<'a>(templates: impl Iterator<Item = (&'a str, &'a Path)>) -> Option<Self> {
14        let _templates = Arc::new(templates
15            .map(|(k, p)| (k.to_owned(), p.to_owned()))
16            .collect::<HashMap<_, _>>());
17
18        let templates = _templates.clone();
19        let mut env = Environment::new();
20        env.set_loader(move |name| {
21            let Some(path) = templates.get(name) else {
22                return Ok(None);
23            };
24
25            match std::fs::read_to_string(path) {
26                Ok(result) => Ok(Some(result)),
27                Err(e) if e.kind() == std::io::ErrorKind::NotFound => Ok(None),
28                Err(e) => Err(
29                    Error::new(ErrorKind::InvalidOperation, "template read failed").with_source(e)
30                ),
31            }
32        });
33
34        let templates = _templates.clone();
35        env.set_auto_escape_callback(move |name| {
36            templates.get(name)
37                .and_then(|path| path.to_str())
38                .map(minijinja::default_auto_escape_callback)
39                .unwrap_or(AutoEscape::None)
40        });
41
42        Some(env)
43    }
44
45    fn render<C: Serialize>(&self, template: &str, context: C) -> Option<String> {
46        let Ok(templ) = self.get_template(template) else {
47            error!(template, "requested template does not exist");
48            return None;
49        };
50
51        match templ.render(context) {
52            Ok(result) => Some(result),
53            Err(e) => {
54                span_error!("templating", template, "failed to render Minijinja template" => {
55                    let mut error = Some(&e as &dyn std::error::Error);
56                    while let Some(err) = error {
57                        error!("{err}");
58                        error = err.source();
59                    }
60                });
61
62                None
63            }
64        }
65    }
66}