i18n.md

App Logic > Output > i18n

In this section, you will learn how to build voice applications that support multiple languages.

• Introduction to i18n
• Configuration
  • Alternative File Paths
  • i18next Configuration Options
• Accessing the Content
• Advanced i18n Features

Introduction to i18n

i18n works by separating the content (the text/speech) from the application logic, to make it easier to switch languages.

Jovo uses a package called i18next to support multilanguage voice apps. You can find all relevant information here: i18next Documentation.

Configuration

Standard Configuration

The easiest way to configure i18n is to use the built-in functionality that requires a separate folder for all language resources:

To get started, create a folder called i18n in /app and add the languageResources using the locale ID (e.g. en-US.json, de-DE.json, en-GB.json, etc.). The file structure should look like this:

{
  "translation": {
    "WELCOME": "Welcome",
    "WELCOME_WITH_PARAMETER": "Welcome {{firstname}} {{lastname}}",
    "WELCOME_ARRAY": [
      "Welcome",
      "Hey",
      "Hello"
    ]
  }
}

You can find out more about how these files are structured here: i18next Essentials.

If you follow these conventions, there is no need to additionally add anything to your app configuration.

This is the default configuration for i18next:

// Using the constructor
const config = {
    i18n: {
        overloadTranslationOptionHandler: sprintf.overloadTranslationOptionHandler,
        load: 'all',
        returnObjects: true,
    },      
    // Other configurations
};

Alternative File Paths

If you want to add files from a different path, go to app.js and add them to the app's configuration.

For example, it could look like this:

const de = require('./somePath/de-DE');
const us = require('./somePath/en-US');

let languageResources = {
    'de-DE': de,
    'en-US': us,
}

// Using the constructor
const config = {
    i18n: {
        resources: languageResources
    },      
    // Other configurations
};

// Using the setter
app.setLanguageResources(languageResources);

i18next Configuration Options

You can also add additional configurations that are available for i18next. Those can be added like this:

// Using the constructor
const config = {
    i18n: {
        returnNull: false,
        fallbackLng: 'en-US',
    },      
    // Other configurations
};

// Using the setter
app.setLanguageResources(languageResources, { returnObjects: true });

You can find a list of i18next configuration options here.

Accessing the Content

In your app logic, you can then use this.t('key') to access the right string. It is also possible to use parameters with this.t('key', {parameter: 'value'}).

Here is some example code for the languageResources object above:

app.setHandler({

    'LAUNCH': function() {
        this.tell(this.t('WELCOME'));
    },

    'HelloWorldIntent': function() {
        this.tell(this.t('WELCOME_WITH_PARAMETER', {firstname: 'John', lastname: 'Doe'}));
    },
});

You can also use it with the Jovo SpeechBuilder, like so:

app.setHandler({

    'LAUNCH': function() {
        let speech = this.speechBuilder()
          .addT('WELCOME');
        this.tell(speech);
    },
});

Or with the ready-made speechBuilder object:

app.setHandler({

    'LAUNCH': function() {
        this.tell(this.speech.addT('WELCOME'));
    },
});

Advanced i18n Features

If you're using the SpeechBuilder, you can also use arrays inside your languageResources for randomized output.

For this, returnObjects config for i18next needs to be enabled (default since Jovo Framework v1.0.0).

For example, your languageResources could look like this:

{
  "translation": {
    "WELCOME": [
      "Welcome",
      "Hey",
      "Hello"
    ]
  }
}

If you're then using a speechBuilder instance, it will use this array to add variety by returning randomized output:

app.setHandler({

    'LAUNCH': function() {
        let speech = this.speechBuilder()
          .addT('WELCOME');
        this.tell(speech);
    },
});

So, without changing any of the code in your handlers, you can vary your output by simply adding new elements to your languageResources.