Rocket-lang provides a configurable enum type for multi-language rocket applications.
A request guard corresponding to the ISO 639-1 code standard. Usage example: ```rust
fn some_path(lang: LangCode) -> Template { // we can now choose which template to display // based of the user's language preference let path = format!("home/{}", LangCode); Template::render(path, json!({})) } ```
The behavior of the enum can be configured with the Config structure, which can be attached to a rocket instance.
When this is not used, its default behavior is to retrieve the language code from the Accept-Language header.
If the preferred method for language resolution is the http accept-language header, the qualities for each language can be set like this:
rust
let config = Config::new();
let config[Es] = 1.0;
let config[En] = 0.5;
The guard can also be configured to extract the language code from a fixed position in the path:
rust
/// takes the language code from the last path segment:
let config = Config::new().url(-1);
This way the language code can be retrieved from a positional url segment. ```rust
fn seelang(lang: LangCode) -> &'static str { lang.asstr() }
```
If none of the previous approaches suit your needs, you may also use a closure to create a language code from a request:
rust
let config = Config::custom(|req: &Request|{
let lang = from_url(req)?;
Ok(lang)
});
Other request guards can consume the structure in their API. Most notably, it can be used by foreign structures to return error messages in multiple languages.
```rust
// here the error message displayed by
// Error will automatically suit the callers configuration.
fn customerrormessage(user: User) -> Error { Error::Unauthorized }
// A possible implementation of Error
impl<'r, 'o: 'r> Responder<'r, 'o> for Error {
fn respondto(self, request: &'r Request<'>) -> rocket::response::Result<'o> {
let lang: LangCode = request
.tryinto()
.maperr(|x: Error| x.status())?;
let msg = match lang {
LangCode::En => "Unauthorized",
LangCode::Es => "No autorizado",
...
};
msg.respond_to(request)
}
}
```