LangApply

A library to create lang objects from locale files (and even to render templates with such values).

How does it work

It reads .toml files from a specified folder and with given options (preCaching, caching, default locale to use, ...).

Then it can load the right localized properties for a given URL and Accept-Language HTTP Header.

For example, if configured to feed from ./lang folder, when asked to load for url /subpage and with locales it, de;q=0.7, fr;q=0.6 it will try to load the file ./lang/subpage/it.toml and pass it to the given callback. Otherwise it will read ./lang/subpage/<X>.toml (where <X> is the configured default locale) and do the same. When a locale file is missing a key, the one from the default locale is used. Use these two files as an example:

• it.toml

    hello = "Ciao"

• en.toml (the example Default Locale)

    hello = "Hello"
    world = "World"

If it.toml is needed, the missing key will be loaded from en.toml. The provided callback will be passed the object

{
    hello: 'Ciao',
    world: 'World'
}

Usage

Initializing

It can be initialized like this.

    const langapply = require('langapply');

    /* ... */
    // How production-mode is detected.
    const production = process.env.NODE_ENV === 'production';

    // These are the default options. Provide your own to modify your experience.
    let defaultOptions = {
        shouldCache: production,
        defaultLocale: 'en',
        preCache: production ? PreCache.All : PreCache.None,
        directory: path.resolve('./lang'),
        loggingLevel: 'info',
    };

    langapply.initialize(defaultOptions); // With default options

Rendering templates

It is meant to be used with Express and it allows to render templates.

You can render them like this.

    // inside your request handler
    langapply.render(
        request,
        response,
        template, // Filename of your template
        context, // The context, context.lang = {/*key-value*/} and context.__lang are inserted.
        callback // The callback to be passed to response.render()
    );

It adds a lang field to your context and calls response.render(). You can access the values by using {{ lang.yourkey }} in case you are using Handlebars templates.

Also you can access the __lang property, which contains the langauge code that is being rendered. For example, you can use this in your templates to define the language used in your HTML document.

Using the middleware

Usage:

app.use(langapply.middleware);

A good way to get things done is by registering langapply.middleware. This middleware processes every GET request and:

1. If present, strips out the langauge prefix and calls next(), so that the request can be processed by other middlewares. This means that, if it receives a request which has /en/page as url, it reroutes it internally to /page by modifying it. Also it sets response.locales.lang to the langauge being rendered. Note that the page is rendered even if the language prefix isn't available.
2. If the language prefix is not valid or present but the header Accept-Language is, then it determines the best language to choose from and redirects the user to the correct page, with a language prefix.
3. If no information is available, the user is simply redirected to the page using the default language.