Phoenix framework - the preferred way to handle internationalization12.06.26

In the Phoenix framework, the preferred way to handle internationalization (i18n) and localization (l10n) is by using the **`gettext`** library. It is the industry standard for Elixir applications and is included by default when you generate a new Phoenix project.

Here is the breakdown of the preferred workflow and best practices:

### 1. The Core: `gettext`
Phoenix uses `gettext` to manage translations. You will find a `lib/my_app_web/gettext.ex` file in your project, which defines the backend for your translations.

### 2. The Workflow
The standard workflow for managing locales in Phoenix follows these steps:

#### A. Marking strings for translation
Instead of hardcoding strings in your templates or code, you wrap them in Gettext macros:
*   **Templates (`.heex`):** Use the `gettext` function.
    ```elixir
    <h1><%= gettext("Welcome to my website") %></h1>
    ```
*   **Elixir Code:** Use the `gettext` macro from your project's Gettext module.
    ```elixir
    import MyAppWeb.Gettext
    # ...
    flash(:info, gettext("Profile updated successfully!"))
    ```

#### B. Extracting strings
Once you have marked your strings, you run a mix task to extract them into `.pot` (Portable Object Template) files:
```bash
mix gettext.extract
```
This scans your code for all `gettext` calls and updates the files in `priv/gettext/default.pot`.

#### C. Translating
For each language you want to support (e.g., French), you create a directory structure: `priv/gettext/fr/LC_MESSAGES/default.po`. You then populate these files with the translations:
```po
msgid "Welcome to my website"
msgstr "Bienvenue sur mon site web"
```

### 3. Handling Locales in the Request Lifecycle
To make your app "locale-aware," you need to set the locale for the current user session. This is typically done via a **Plug**.

1.  **Create a Plug:** Create a `SetLocale` plug that checks the URL (e.g., `example.com/fr/dashboard`), a cookie, or the `Accept-Language` header.
2.  **Set the Locale:** Use `Gettext.put_locale/1` inside that plug.
    ```elixir
    def call(conn, _opts) do
      locale = get_locale_from_params(conn) || "en"
      Gettext.put_locale(MyAppWeb.Gettext, locale)
      conn
    end
    ```
3.  **Plug it in:** Add this plug to your `router.ex` inside the `:browser` pipeline.

### 4. Best Practices
*   **Use `dgettext` for domains:** If your app is large, don't put all strings in `default.po`. Use `dgettext("errors", "...")` to split translations into different files (e.g., `errors.po`, `emails.po`).
*   **Use `ngettext` for plurals:** Always use `ngettext` when dealing with quantities to handle different pluralization rules across languages.
    ```elixir
    ngettext("You have one message", "You have %{count} messages", count)
    ```
*   **Keep keys as English:** Use the English sentence as the `msgid`. This makes the code readable even if the translation files aren't updated yet.
*   **Use `cldr` for formatting:** While `gettext` handles text, it does not handle date/time or currency formatting. For those, use the [ex_cldr](https://github.com/elixir-cldr/cldr) library, which is the standard companion to `gettext` for full localization.

### Summary
1.  **`gettext`** is the tool for text.
2.  **`mix gettext.extract`** is your best friend for maintenance.
3.  **Plugs** are the preferred way to switch locales per request.
4.  **`ex_cldr`** is the preferred way to handle localized numbers, dates, and currencies.

https://www.phoenixframework.org/

Anonymous

Phoenix framework - the preferred way to handle internationalization12.06.26

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