React-Intl如何从变量切换语言环境和消息

Question

我正试图弄清楚如何使用React-Intl更改语言.这是我的第一个React App,它是用create-react-app制作的,我没有使用Redux和Flux.

在我的index.js中,我有以下代码:

import React from 'react';
import ReactDOM from 'react-dom';
import TodoApp from './components/TodoApp';
import registerServiceWorker from './registerServiceWorker';
import './index.css';

// Bootstrap CSS libraries
import 'bootstrap/dist/css/bootstrap.css';
import 'bootstrap/dist/css/bootstrap-theme.css';

import { IntlProvider, addLocaleData } from 'react-intl';
import intlEN from 'react-intl/locale-data/en';
import intlES from 'react-intl/locale-data/es';
import intlMessagesES from './i18n/locales/es.json';
import intlMessagesEN from './i18n/locales/en.json';

addLocaleData([...intlEN, ...intlES]);

/* Define your translations */
let i18nConfig = {
    locale: 'es',
    messages: intlMessagesES
};

let changeLanguage = (lang) => {
    i18nConfig = { locale: lang, messages: intlMessagesEN };
    return i18nConfig;
}

ReactDOM.render(
    <IntlProvider locale={ i18nConfig.locale } key={ i18nConfig.locale } messages={ i18nConfig.messages }>
        <TodoApp onChangeLanguage={changeLanguage} />
    </IntlProvider>,
    document.getElementById('root'));
registerServiceWorker();

TodoApp通过道具发送'lang'参数的字符串(即:'es'或'en'),当我改变i18nConfig时,IntlProvider似乎没有任何改变.我的想法是改变我的i18nConfig变量,然后我的所有应用程序也会改变语言.

我在TodoApp中有FormattedMessages,我的两条JSON消息填充如下:

// i18n/locales/en.json
{
  "footer.add.placeholder": "Enter a name ...",
  "footer.add.priority0.text": "No priority",
  "footer.add.priority1.text": "Priority 1",
   ...
}

你知道我的代码中缺少什么吗？也许我对React-Intl一无所知.任何建议都会有所帮助,谢谢.

Answer 1

如果你从root删除所有它:

ReactDOM.render(<TodoApp />, document.getElementById('root'));

但现在我们改变TodoApp组件如下:

1)我们将'locale'添加为组件状态并导入React-Intl:

import { IntlProvider, addLocaleData } from 'react-intl';
import intlEN from 'react-intl/locale-data/en';
import intlES from 'react-intl/locale-data/es';
import intlMessagesES from './../i18n/locales/es.json';
import intlMessagesEN from './../i18n/locales/en.json';

addLocaleData([...intlEN, ...intlES]);

/* Define your default translations */
let i18nConfig = {
    locale: 'en',
    messages: intlMessagesEN
};

2)更改我们的changeLanguage函数(这次称为'onChangeLanguage'),此函数从subComponent语言选择器接收'lang':

onChangeLanguage(lang) {
        switch (lang) {
            case 'ES': i18nConfig.messages = intlMessagesES; break;
            case 'EN': i18nConfig.messages = intlMessagesEN; break;
            default: i18nConfig.messages = intlMessagesEN; break;
        }
        this.setState({ locale: lang });
        i18nConfig.locale = lang;
}

最后渲染:

render() {
        return (
            <IntlProvider key={ i18nConfig.locale } locale={ i18nConfig.locale }  messages={ i18nConfig.messages }>
                <div>
                    <Header onChangeLanguage={this.onChangeLanguage} />
                    // Other components ...
                </div>
            </IntlProvider>
        );
    }

如果有人根本不理解,请在评论中提问!感谢@TomásEhrich

Answer 2

使用新的React Context API,它很容易实现.创建一个包装器:

import React from "react";
import Types from "prop-types";
import { IntlProvider, addLocaleData } from "react-intl";
import en from "react-intl/locale-data/en";
import de from "react-intl/locale-data/de";
import deTranslation from "../../lang/de";
import enTranslation from "../../lang/en";

addLocaleData([...en, ...de]);

const Context = React.createContext();

class IntlProviderWrapper extends React.Component {
  constructor(...args) {
    super(...args);

    this.switchToEnglish = () =>
      this.setState({ locale: "en", messages: enTranslation });

    this.switchToDeutsch = () =>
      this.setState({ locale: "de", messages: deTranslation });

    // pass everything in state to avoid creating object inside render method (like explained in the documentation)
    this.state = {
      locale: "en",
      messages: enTranslation,
      switchToEnglish: this.switchToEnglish, 
      switchToDeutsch: this.switchToDeutsch 
    };
  }

  render() {
    const { children } = this.props;
    const { locale, messages } = this.state;
    return (
      <Context.Provider value={this.state}>
        <IntlProvider
          key={locale}
          locale={locale}
          messages={messages}
          defaultLocale="en"
        >
          {children}
        </IntlProvider>
      </Context.Provider>
    );
  }
}

export { IntlProviderWrapper, Context as IntlContext };

然后使用提供者和消费者:

import { Provider } from "react-redux";
import {  IntlProviderWrapper } from "./IntlContext";

class App extends Component {
  render() {
    return (
      <Provider store={store}>
        <IntlProviderWrapper>
          ...
        </IntlProviderWrapper>
      </Provider>
    );
  }
}

在应用程序的某个地方:

import React from "react";
import { Text, Button } from "native-base";
import { IntlContext } from "../IntlContext";

const LanguageSwitch = () => (
  <IntlContext.Consumer>
    {({ switchToEnglish, switchToDeutsch }) => (
      <React.Fragment>
        <button onClick={switchToEnglish}>
          English
        </button>
        <button onClick={switchToDeutsch}>
          Deutsch
        </button>
      </React.Fragment>
    )}
  </IntlContext.Consumer>
);

// with hooks
const LanguageSwitch2 = () => {
  const { switchToEnglish, switchToDeutsch } = React.useContext(IntlContext);
  return (
    <>
      <button onClick={switchToEnglish}>English</button>
      <button onClick={switchToDeutsch}>Deutsch</button>
    </>
  );
};

export default LanguageSwitch;

以下是具有更一般解决方案的相关存储库.

注意:目前,react-intl仍在使用旧的上下文API,但在未来的解决方案中,这样的解决方案可能是开箱即用的.