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How to Integrate React Intl

1. Merge feature/react-intl branch with git. Because react-intl integration is built on top of feature/redux, you’ll also get all the features.

2. Adjust INTL_REQUIRE_DESCRIPTIONS constant in tools/webpack.config.js around line 17:

   const INTL_REQUIRE_DESCRIPTIONS = true;
   

   When this boolean is set to true, the build will only succeed if a description is set for every message descriptor.

3. Adjust locales settings in src/config.js:

   // default locale is the first one
   export const locales = ['en-GB', 'cs-CZ'];
   

   Note that you should follow BCP 47 (RFC 5646).

4. Add locale support in src/client.js:

   import en from 'react-intl/locale-data/en';
   import cs from 'react-intl/locale-data/cs';
   ...
   
   [en, cs].forEach(addLocaleData);
   

5. Execute yarn run messages or yarn start to strip out messages. Message files are created in src/messages directory.

6. Edit src/messages/*.json files, change only message property.

7. Execute yarn run build, your translations should be copied to build/messages/ directory.

How to write localizable components

Just import the appropriate component from react-intl

• For localizable text use <FormattedMessage>.

• You can also use it with the defineMessages() helper.

• For date and time: <FormattedDate> <FormattedTime> <FormattedRelative>

• For numbers and currencies: <FormattedNumber> <FormattedPlural>

• If possible, do not use <FormattedHTMLMessage>, see how to use Rich Text Formatting with <FormattedMessage>

• When you need an imperative formatting API, use the injectIntl High-Order Component.

Example

import {
  defineMessages,
  FormattedMessage,
  injectIntl,
  intlShape,
} from 'react-intl';

const messages = defineMessages({
  text: {
    id: 'example.text',
    defaultMessage: 'Example text',
    description: 'Hi Pavel',
  },
  textTemplate: {
    id: 'example.text.template',
    defaultMessage: 'Example text template',
    description: 'Hi {name}',
  },
});

function Example(props) {
  const text = props.intl.formatMessage(messages.textTemplate, {
    name: 'Pavel',
  });
  return (
    <div>
      <FormattedMessage
        id="example.text.inlineDefinition"
        defaultMessage="Hi Pavel"
        description="Example of usage without defineMessages"
      />
      <FormattedMessage {...messages.text} />
      <FormattedMessage
        {...messages.textTemplate}
        values=
      />
    </div>
  );
}

Example.propTypes = {
  intl: intlShape,
};

export default injectIntl(Example);

Updating translations

When running the development server, every source file is watched and parsed for changed messages.

Messages files are updated on the fly. If a new definition is found, this definition is added to the end of every used src/messages/xx-XX.json file so when committing, new translations will be at the tail of file.

When an untranslated message is removed and its message field is empty as well, the message will be deleted from all translation files. This is why the files array is present.

When editing a translation file, it should be copied to build/messages/ directory.

Other References

• Intl documentation on MDN
• express-request-language – for more details how initial language negotiation works.

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