Updating Locale

Locale may be explicitly set by setting props on the decorator or by calling the updateLocale function via context. Apps should use only one of these methods to set locale or conflicts could arise (for example, if a re-render of the root component caused the locale to be reset).

Using context

Context is the easiest way to update the locale. Call the updateLocale function, passing the locale string (e.g. context.updateLocale('en-US'):

import {I18nContextDecorator} from '@enact/i18n/I18nDecorator';
import {Component} from 'react';

const SomeComponent = I18nContextDecorator(
	{updateLocaleProp: 'updateLocale'},
	class extends Component {
		...
		changeLocale = (locale) => {
			this.props.updateLocale(locale);
		}
		...
	}
);

Updating locale via props

The other way to update locale is to send a prop down through the decorator (directly or through moonstone/MoonstoneDecorator).

A typical app looks like this:

//Typically inside app.js
export default MoonstoneDecorator(App);

//Typically inside index.js
import App from './App';

ReactDOM.render(<App />, document.getElementById('root'))
// or if you're using redux

ReactDOM.render(
	<Provider store={store}>
		<App />
	</Provider>,
	document.getElementById('root')
);

The <App /> component in index.js can receive props. The decorator accepts a locale prop, which accepts the desired locale string.

An example usage may look like this:

const AppWrapped = (props) => (
	<App locale={props.locale}/>
)

In a deeply nested app, passing props back to the root element can get messy. State management libraries such as Redux can assist with this.

Using redux, a connected component can be used as shown below:

// Inside app.js
const mapStateToProps = (state) => (
	{
		locale: state.locale
	}
)

export default connect(mapStateToProps)(MoonstoneDecorator(App));

This would allow you to control locale information through Redux. However, there are some issues with this approach, explained below.

Issue with context and Redux

Using context and Redux together has one major problem. When relying on using the rtl property from context to update a component, the react-redux connect method will suppress updates caused by context changes.

The reason is that connect only checks to see if props have changed, not context. If you only update context then the component will not re-render. To circumvent this you must use connect with the option pure set to false like this:

export default connect(mapStateToProps, mapDispatchToProps, null, {pure: false})(LocaleSwitch);

This will allow the context to flow through to the component, but it will also cause performance issues because your component will be re-rendering on every change. If you must use context with react-redux, please make the component as small as possible to reduce re-renders or use shouldComponentUpdate.