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igmarin/elixir-phoenix-skills

Curated library of 38 atomic skills, 7 personas, and 1 orchestrator for Elixir and Phoenix development. Organized by category: fundamentals, phoenix, database, testing, auth, infrastructure, quality, security, integrations, tooling, frameworks, personas, and orchestration. Covers core Elixir patterns, Phoenix LiveView, Ecto, OTP, Oban, testing, security, deployment, real-time, and modern tooling (Req, Swoosh, Cachex, Broadway, Ash).

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SKILL.mdskills/integrations/gettext-i18n/

name:
gettext-i18n
type:
atomic
tags:
atomic
license:
MIT
description:
Use when implementing internationalization (i18n) in Elixir/Phoenix applications. Invoke before adding translations or supporting multiple languages. Covers Gettext setup, translation functions, pluralization, locale management, and .po/.pot file workflows. Trigger words: gettext, i18n, internationalization, translation, locale, pluralization, multiple languages.
metadata:
{"user-invocable":"true","version":"1.0.0"}

Gettext Internationalization

Gettext is the standard internationalization library for Elixir/Phoenix applications.

End-to-End Workflow

  1. Add Gettext calls — wrap strings with gettext/1, dgettext/2, or ngettext/3 in templates, LiveView, and controllers
  2. Extract strings — run mix gettext.extract --merge to generate/update .pot and .po files
  3. Verify .po files — confirm new msgid entries appear with empty msgstr values
  4. Add translations — fill in msgstr values for each target locale
  5. Set locale per request — configure a plug or LiveView mount to call Gettext.put_locale/2
  6. Test — assert translated strings appear when locale is set

Key Rules

  • Only translate user-facing text — do not translate error messages intended for logs
  • Use domain-specific contexts — dgettext("errors", "Not found") keeps error strings in a separate .po file from default content

Setup

# mix.exs
defp deps do
  [
    {:gettext, "~> 0.26"}
  ]
end

Gettext Module

# lib/my_app_web/gettext.ex
defmodule MyAppWeb.Gettext do
  use Gettext.Backend, otp_app: :my_app
end

Using Translations

In Templates

<h1><%= gettext("Welcome to our site") %></h1>

<p>
  <%= gettext("You have %{count} new messages", count: @message_count) %>
</p>

<%# Pluralization: pass count as both the integer and a binding %>
<%= ngettext("There is %{count} item", "There are %{count} items", @item_count, count: @item_count) %>

In LiveView

defmodule MyAppWeb.HomeLive do
  use MyAppWeb, :live_view
  import MyAppWeb.Gettext

  @impl true
  def mount(_params, session, socket) do
    locale = session["locale"] || "en"
    Gettext.put_locale(MyAppWeb.Gettext, locale)

    {:ok, assign(socket, :greeting, gettext("Hello!"))}
  end
end

In Controllers

defmodule MyAppWeb.PageController do
  use MyAppWeb, :controller
  import MyAppWeb.Gettext

  def index(conn, _params) do
    message = gettext("Welcome to %{app_name}", app_name: "MyApp")
    render(conn, :index, message: message)
  end
end

Translation Files

Directory Structure

priv/gettext/
├── en/LC_MESSAGES/
│   ├── default.po      # Default domain
│   └── errors.po       # Errors domain
├── es/LC_MESSAGES/
│   ├── default.po
│   └── errors.po
└── default.pot         # Template file

PO File Format

# priv/gettext/es/LC_MESSAGES/default.po
msgid "Welcome to our site"
msgstr "Bienvenido a nuestro sitio"

msgid "You have %{count} new message"
msgid_plural "You have %{count} new messages"
msgstr[0] "Tienes %{count} mensaje nuevo"
msgstr[1] "Tienes %{count} mensajes nuevos"

Extracting Translations

# Extract new strings to .pot files
mix gettext.extract

# Merge .pot files into .po files
mix gettext.merge priv/gettext

# Extract and merge in one step
mix gettext.extract --merge

Validate: After extraction, open the relevant .po files and confirm new msgid entries appear with empty msgstr values. Fill in translations before deploying.

Setting Locale

# lib/my_app_web/plugs/set_locale.ex
defmodule MyAppWeb.Plugs.SetLocale do
  import Plug.Conn

  @supported_locales ~w(en es fr de)

  def init(opts), do: opts

  def call(conn, _opts) do
    locale =
      get_locale_from_params(conn) ||
      get_locale_from_session(conn) ||
      "en"

    Gettext.put_locale(MyAppWeb.Gettext, locale)
    conn
  end

  defp get_locale_from_params(conn), do: validate(conn.params["locale"])
  defp get_locale_from_session(conn), do: validate(get_session(conn, "locale"))

  defp validate(locale) when locale in @supported_locales, do: locale
  defp validate(_), do: nil
end

Register it in the router pipeline:

pipeline :browser do
  # ...
  plug MyAppWeb.Plugs.SetLocale
end

Testing Translations

defmodule MyAppWeb.PageTest do
  use MyAppWeb.ConnCase

  test "renders translated welcome message", %{conn: conn} do
    Gettext.put_locale(MyAppWeb.Gettext, "es")

    conn = get(conn, ~p"/")

    assert html_response(conn, 200) =~ "Bienvenido"
  end
end

skills

integrations

gettext-i18n

SKILL.md

README.md

tile.json