Translation

Chat messages can be translated on-demand or automatically, this allows users speaking different languages on the same channel.

Message Translation Endpoint

This API endpoint translates an existing message to another language. The source language is inferred from the user language or detected automatically by analyzing its text. If possible it is recommended to store the user language, see " Set user language " section later in this page.

var channel = await Client.GetOrCreateChannelWithIdAsync(ChannelType.Messaging, "channel-id");
var message = await channel.SendNewMessageAsync("Hello, world!");

// Translate into French (ISO language code). The translation is stored on the
// message. Every client watching the channel receives a MessageUpdated event.
await message.TranslateAsync("fr");

// Translations are on I18n under the "{language}_text" key, plus a "language"
// key for the detected source language.
var frenchText = message.I18n["fr_text"];

The endpoint returns the translated message, updates it and sends a message.updated event to all users on the channel.

i18n data

When a message is translated, the i18n object is added. The i18n includes the message text in all languages and the code of the original language.

The i18n object has one field for each language named using this convention language-code_text

Here is an example after translating a message from english into French and Italian.

{
  "fr_text": "Bonjour, J'aimerais avoir plus d'informations sur votre produit.",
  "it_text": "Ciao, vorrei avere maggiori informazioni sul tuo prodotto.",
  "language": "en"
}

// Translations are exposed on the message as the I18n dictionary
foreach (var pair in message.I18n)
{
    Debug.Log($"{pair.Key} = {pair.Value}"); // e.g. "fr_text = Bonjour, ..."
}

// The original language is under the "language" key
if (message.I18n.TryGetValue("language", out var originalLanguage))
{
    Debug.Log(originalLanguage); // "en"
}

// Read a specific translation, falling back to the original text
var text = message.I18n.TryGetValue("fr_text", out var french) ? french : message.Text;

Automatic translation

Automatic translation translates all messages immediately when they are added to a channel and are delivered to the other users with the translated text directly included.

Automatic translation works really well for 1-1 conversations or group channels with two main languages.

Let's see how this works in practice:

1. A user sends a message and automatic translation is enabled

2. The language set for that user is used as source language (if not the source language will be automatically detected)

3. The message text is translated into the other language in used on the channel by its members

Enabling automatic translation

Automatic translation is not enabled by default. You can enable it for your application via API or CLI from your backend. You can also enable auto translation on a channel basis.

// Enable auto-translation for a single channel
await channel.UpdatePartialAsync(new StreamUpdateChannelPartialRequest
{
    AutoTranslationEnabled = true,
    AutoTranslationLanguage = "en",
});

// Read the current settings back from the channel
Debug.Log(channel.AutoTranslationEnabled);
Debug.Log(channel.AutoTranslationLanguage);

// Enabling auto-translation for the whole app is a server-side operation.
// Use one of our server-side SDKs or the Stream Dashboard for that.

Set user language

In order for auto translation to work, you must set the user language or specify a destination language for the channel using the auto_translation_language field (see previous code example).

// Set the language used to translate messages for a user
await Client.UpsertUsersAsync(new[]
{
    new StreamUserUpsertRequest
    {
        Id = "user-id",
        Language = "fr"
    }
});

Caveats and limits

• Translation is only done for messages with up to 5,000 characters. Blowin' In The Wind from Bob Dylan contains less than 1,000 characters

• Error messages and commands are not translated (ie. /giphy hello)

• When a message is updated, translations are recomputed automatically

• Changing translation settings or user language have no effect on messages that are already translated

• If there are three or more languages being used by channel members, auto-translate will default to the most common language used by the channel members. Therefore, this feature is best suited for groups with a maximum of two main languages.

Available Languages