Message Format support for localization

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• Guidelines for Developers
• Tools and further information

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In Discourse all Message Format strings have a key that ends with "_MF". The Crowdin Editor has a preview that allows you to experiment with various values which is quite helpful for checking your translations.

Important: You need to modify the plural forms of your translation if your language uses forms other than "one" and "other". You can add or remove forms within a { FOO, plural, ... } block in order to make it work for your languages. The preview in the Crowdin Editor will show you a "Syntax error" in the preview when there's a problem with your translation.

The available plural forms are:

• zero
• one
• two
• few
• many
• other (required — general plural form — also used for languages with no distinction between singular and plural forms)

Sometimes you might see an empty =0 {} block in an English source string which means that the variable can't have a value of 0.

Guidelines for Developers

Message Format strings are currently only available only for client-side translations. They are useful if your string contains more than one number or many variables which would lead to a high amount of permutations.

• The keys of Message Format strings need to end with "_MF"

• Use the following format for numbers (# will be replaced with the number):

  { variable_name, plural,
      one: {# singular text}
    other: {# plural text}
  }
  

• Use the following format for choices:

  { variable_name, select,
    foo: {This is foo}
    bar: {This is bar}
    baz: {This is baz}
  }
  

• This is how you use it in JavaScript:

  I18n.messageFormat("key_MF", {
    variable1: "foo",
    variable2: 42,
  });
  

• :loudspeaker: Recommendation: If possible, use complex arguments as the outermost structure of a message, and write full sentences in their sub-messages. If you have nested select and plural arguments, place the select arguments (with their fixed sets of choices) on the outside and nest the plural arguments (hopefully at most one) inside. See https://unicode-org.github.io/icu/userguide/format_parse/messages/

• Make them readable -- see existing examples in client.en.yml

  ❌ Bad

  There {currentTopics, plural, one {is <strong>#</strong> topic} other {are <strong>#</strong> topics}}. Visitors need more to read and reply to – we recommend at least { requiredTopics, plural, one {<strong>#</strong> topic} other {<strong>#</strong> topics}}. Only staff can see this message.
  

  💚 Good

  There { currentTopics, plural,
      one {is <strong>#</strong> topic}
    other {are <strong>#</strong> topics}
  }. Visitors need more to read and reply to – we recommend at least { requiredTopics, plural,
      one {<strong>#</strong> topic}
    other {<strong>#</strong> topics}
  }. Only staff can see this message.
  

Tools and further information

• https://format-message.github.io/icu-message-format-for-translators/editor.html allows you to test a Message Format string in case there's a problem with the Crowdin Editor. Please disable the "Parse simple xml/html tags" option, otherwise you might see an error message.

• https://format-message.github.io/icu-message-format-for-translators/