Translation and i18n

The Stream Chat React component library uses the i18next dependency to create a Streami18n class constructor that handles language translation of our UI components. The Stream Chat API also supports automatic translation of chat messages, learn more.

Supported Languages

The library provides built-in translations for the following languages:

1. English (en) - default
2. Dutch (nl)
3. French (fr)
4. German (de)
5. Hindi (hi)
6. Italian (it)
7. Japanese (ja)
8. Korean (ko)
9. Portuguese (pt)
10. Russian (ru)
11. Spanish (es)
12. Turkish (tr)

If you wish to change the default language in your app without initiating an instance of Streami18n, pass the defaultLanguage prop to the Chat component on load of your application. The below code snippet will change the default language from English to Italian.

const defaultLanguage = "it";

<Chat client={client} defaultLanguage={defaultLanguage}>
  ...
</Chat>;

The following screenshots show the state of the UI components in the app before and after setting the defaultLanguage to Italian.

Default language not specified:

Default language set to Italian:

Enable Localization

The library supports two different methods for manually setting the language of the connected user and automatically translates all text built into the UI components. The simpler and less customizable way is to set the language value in the connectUser method on mount of the chat application.

client.connectUser({ id: userId, language: "es" }, userToken);

Create a Streami18n Instance

Additionally, you can create a class instance of Streami18n and pass as a prop into the Chat component. The below example changes the current user’s language to Spanish.

const i18nInstance = new Streami18n({ language: "es" });

<Chat client={client} i18nInstance={i18nInstance}>
  ...
</Chat>;

Override Default Translations

Taking it one step further, the below example shows how to override the default text values built into the components.

const i18nInstance = new Streami18n({
  language: "es",
  translationsForLanguage: {
    "Nothing yet...": "Nada!", // default is 'Nada aun...'
  },
});

<Chat client={client} i18nInstance={i18nInstance}>
  ...
</Chat>;

If you wish to completely override one of our language files, provide your custom translations via the translationsForLanguage key. Your custom language file must include all of the keys of the default file.

import esUpdated from "path/to/esUpdated.json";

const i18nInstance = new Streami18n({
  language: "es",
  translationsForLanguage: esUpdated,
});

<Chat client={client} i18nInstance={i18nInstance}>
  ...
</Chat>;

If the language for the connected user is not manually set by passing a Streami18n object to the Chat component, the component library detects the user’s default browser language. If the component library has translation support for the detected browser language, either through the languages provided or by a custom added language (described below), the connected user’s language is automatically set to this value. If the browser language is not supported for translation, the library defaults to English.

Overriding ARIA labels

ARIA labels that are used for interactive elements are also subject to localization. Translation keys for ARIA labels are prefixed by aria/:

import { useTranslationContext } from "stream-chat-react";

const Component = () => {
  const { t } = useTranslationContext();
  return (
    <button type="button" aria-label={t("aria/Send")}>
      📨
    </button>
  );
};

To override the default translations, add an aria-prefixed key to the translationsForLanguage object:

const i18nInstance = new Streami18n({
  language: "en",
  translationsForLanguage: {
    "aria/Send": "Send Message",
  },
});

<Chat client={client} i18nInstance={i18nInstance}>
  {/* ... */}
</Chat>;

Add a Language

In the following example, we will demonstrate how to add translation support for an additional language not currently supported by the component library. We will add translations for Simplified Chinese, which uses language code zh, by following these steps:

1. Create a JSON file in your project (ex: zh.json if creating a translation file for Simplified Chinese)
2. Copy the content of an existing translation file
3. Change the values to your desired translations
4. Register the translation file and set the new language
5. Pass as a prop to the Chat component

We can initialize the instance dynamically:

import zhTranslation from "path/to/zh.json";

const i18nInstance = new Streami18n();

const App = () => {
  const [languageLoaded, setLanguageLoaded] = useState(false);

  useEffect(() => {
    const loadLanguage = async () => {
      i18nInstance.registerTranslation("zh", zhTranslations);
      await i18nInstance.setLanguage("zh");
      setLanguageLoaded(true);
    };

    loadLanguage();
  }, []);

  if (!languageLoaded) return null;

  return (
    <Chat client={client} i18nInstance={i18nInstance}>
      ...
    </Chat>
  );
};

Or we can have a pre-configured Streami18n instance:

import zhTranslation from 'path/to/zh.json';

const i18nInstance = new Streami18n({
  language: 'zh',
  translationsForLanguage: zhTranslations,
  dayjsLocaleConfigForLanguage: {
    // see the next section about Datetime translations
    months: [...],
    monthsShort: [...],
    calendar: {
      sameDay: ...'
    }
  }
});

const App = () => {
  return (
    <Chat client={client} i18nInstance={i18nInstance}>
      ...
    </Chat>
  );
};

Datetime translations

The SDK components use Dayjs internally by default to format dates and times. It has locale support being a lightweight alternative to Momentjs with the same modern API. Dayjs provides locale config for plenty of languages.

You can either provide the Dayjs locale config while registering language with Streami18n (either via constructor or registerTranslation()) or you can provide your own Dayjs or Momentjs instance to Streami18n constructor, which will be then used internally (using the language locale) in components.

1. Via language registration

const i18n = new Streami18n({
 language: 'nl',
 dayjsLocaleConfigForLanguage: {
   months: [...],
   monthsShort: [...],
   calendar: {
     sameDay: ...'
   }
 }
});

Similarly, you can add locale config for Momentjs while registering translation via registerTranslation function.

const i18n = new Streami18n();

i18n.registerTranslation(
 'mr',
 {
   'Nothing yet...': 'काहीही नाही  ...',
   '{{ firstUser }} and {{ secondUser }} are typing...': '{{ firstUser }} आणि {{ secondUser }} टीपी करत आहेत ',
 },
 {
   months: [...],
   monthsShort: [...],
   calendar: {
     sameDay: ...'
   }
 }
);

2. Provide your own Momentjs object

import 'moment/locale/nl';
import 'moment/locale/it';
// or if you want to include all locales
import 'moment/min/locales';

import Moment from moment

const i18n = new Streami18n({
 language: 'nl',
 DateTimeParser: Moment
})

3. Provide your own Dayjs object

import Dayjs from "dayjs";

import "dayjs/locale/nl";
import "dayjs/locale/it";
// or if you want to include all locales
import "dayjs/min/locales";

const i18n = new Streami18n({
  language: "nl",
  DateTimeParser: Dayjs,
});

If you would like to stick with english language for dates and times in Stream components, you can set disableDateTimeTranslations to true.

Timezone location

To display date and time in different than machine’s local timezone, provide the timezone parameter to the Streami18n constructor. The timezone value has to be a valid timezone identifier string. If no timezone parameter is provided, then the machine’s local timezone is applied.

import { Streami18n } from "stream-chat-react";

const streamI18n = new Streami18n({ timezone: "Europe/Prague" });

If you are using moment as your datetime parser engine and want to start using timezone-located datetime strings, then we recommend to use moment-timezone instead of moment package. Moment Timezone will automatically load and extend the moment module, then return the modified instance. This will also prevent multiple versions of moment being installed in a project.

import type momentTimezone from "moment-timezone";
import { Streami18n } from "stream-chat-react";

const i18n = new Streami18n({
  DateTimeParser: momentTimezone,
  timezone: "Europe/Prague",
});

Translating Messages

Stream Chat provide the ability to run users’ messages through automatic translation. While machine translation is never perfect it can enable two users to communicate with each other without speaking the same language. For more information, see the full guide to adding automatic translation.

Diacritics and Transliteration

Searching for users when utilizing the ’@’ mentions command supports diacritics and, optionally, transliteration using Transliterate. To add transliteration to your search functionality with the external Transliterate library, use the useMentionsTransliteration prop in the MessageInput. This library is dynamically imported if the prop is true. Diacritics support is available by default.

Streami18n API Reference

The Streami18n class wraps i18next and provides a set of values and methods.

Class Constructor Options

parseMissingKeyHandler

The default implementation returns the default value provided to the translator function, for example the component below will display string 'hello' if the key 'some-key' is not found among the translations for a given language:

import { useTranslationContext } from "stream-chat-react";

const Component = () => {
  const { t } = useTranslationContext("useCommandTrigger");

  return <div>{t("some-key", { defaultValue: "hello" })}</div>;
};

The custom handler may log missing key warnings to the console in the development environment:

import { Streami18n, Streami18nOptions } from "stream-chat-react";

const parseMissingKeyHandler: Streami18nOptions["parseMissingKeyHandler"] = (
  key: string,
  defaultValue?: string,
) => {
  console.warn(`Streami18n: Missing translation for key: ${key}`);
  return defaultValue ?? key;
};

const i18nInstance = new Streami18n({ parseMissingKeyHandler });

Class Instance Methods

getAvailableLanguages

Returns an array of language code strings corresponding to available languages.

const availableLanguages = streami18n.getAvailableLanguages();

geti18Instance

Returns the instance of i18next used within the Streami18n instance.

const i18nInstance = streami18n.geti18Instance();

getTranslations

Returns the current translation dictionaries for all languages.

const translations = streami18n.getTranslations();

getTranslators

Asynchronous function that returns the current translator functions.

const { t, tDateTimeParser } = await streami18n.getTranslators();

registerTranslation

Allows you to register a custom translation, which overrides an existing translation for the given language. The third parameter, which is an optional Day.js locale, is structured the same as dayjsLocaleConfigForLanguage.

Review the enTranslations JSON file exported from stream-chat-react for a current list of translation keys.

streami18n.registerTranslation("es", {
  "Nothing yet...": "Nada!",
});

Parameters

setLanguage

Asynchronous function that changes the current language and returns a new translation function. If not initialized, undefined will be returned. If the language fails to update, the current translation function will be returned.

const t = await streami18n.setLanguage("nl");

Parameters