Languages

leptos-fluent follows a default strategy to generate the languages of the application. This strategy is based on the locales/ directory.

Giving the next directory structure:

.
└── 📁 locales
    ├── 📁 en
    │   └── 📄 main.ftl
    └── 📁 es-ES
        └── 📄 main.ftl

The framework will generate something like the following languages array at compile time:

let LANGUAGES = [
  leptos_fluent::Language {
    id: "en",
    name: "English",
    dir: leptos_fluent::WritingDirection::Ltr,
    flag: Some("🇬🇧"),
    script: None,
  },
  leptos_fluent::Language {
    id: "es-ES",
    name: "Español (España)",
    dir: leptos_fluent::WritingDirection::Ltr,
    flag: Some("🇪🇸"),
    script: None,
  },
]

• en is built with the name "English" because it's defined as an ISO 639 language code, without a region code.
• es-ES is built with the name "Español (España)" because it's defined as an ISO 639 language code and a ISO 3166 region code.

This enforces that a user will always be able to select their language in their own language, and not in the current language of the application.

Inferred language names

When not using a languages file, the language names are inferred from the language codes used for locales directories following the next rules:

1. If only a language code is provided, use "Language name" (see full-list).
2. If a region code is provided but the language is not repeated, use "Language name".
3. If a region code is provided and the language is repeated, use "Language name (region name)" (see full list).

The languages file

The languages array can be fully customized by defining a languages parameter in the leptos_fluent! macro pointing to a languages file. This file must be relative to the Cargo.toml file.

leptos_fluent! {
    languages: "./locales/languages.json",
    // ...
}

[
  ["en", "English"],
  ["es-ES", "Spanish (Spain)", "auto"]
]

Languages file format

In order to use a languages file, you must enable the feature for the file format you want to use in the Cargo.toml file:

[dependencies]
leptos-fluent = { version = "0.3", features = ["json5"] }

Available features for languages file formats are:

• json: JSON
• yaml: YAML
• json5: JSON5

Languages file layout

The languages file must expose an array of arrays with the structure:

[
  // Code, Name,            "ltr"/"rtl"/"auto" (optional)
  ["code", "Language name", "Writing direction"],
]

If default_language parameter is not passed to leptos_fluent! macro, the first one in the languages file or language code folder by their alphabetical order will used as the initial of the user when no other initialization language is discovered.

#[component]
pub fn App() -> impl IntoView {
    leptos_fluent! {
        languages: "./locales/languages.json5",
        default_language: "en",
    };
}

// ./locales/languages.json5
[
  ["en", "English"],
  ["es-ES", "Español (España)"],
]