React 进阶提高免费视频教程 #22 从 Redux 迁移到 React 16.3 的 Context API 之实践

练习的源码：https://github.com/hfpp2012/redux-reminder-pro

https://www.qiuzhi99.com/movies/react-jin-jie-ti-gao-21-react-16-3-quan-xin-context-api-shi-jian

src/contexts/ReminderContext.js

import React, { Component } from 'react';
import { bake_cookie, read_cookie } from 'sfcookies';

export const ReminderContext = React.createContext();

export class ReminderProvider extends Component {
  state = {
    reminders: read_cookie("reminders") || []
  }

  addReminder = (text, dueDate) => {
    let reminders = [];
    reminders = [
      ...this.state.reminders,
      { id: Math.random(), text, dueDate }
    ];
    this.setState({
      reminders: reminders
    });
    bake_cookie("reminders", reminders);
  }

  deleteReminder = (id) => {
    let reminders = [];
    reminders = this.state.reminders.filter(reminder => reminder.id !== id);
    this.setState({
      reminders: reminders
    });
    bake_cookie("reminders", reminders);
  }

  clearReminders = () => {
    this.setState({
      reminders: []
    });
    bake_cookie("reminders", []);
  }

  render() {
    return (
      <ReminderContext.Provider
        value={{
          reminders: this.state.reminders,
          addReminder: this.addReminder,
          deleteReminder: this.deleteReminder,
          clearReminders: this.clearReminders
        }}
      >
        { this.props.children }
      </ReminderContext.Provider>
    );
  }
}

src/index.js

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

import { ReminderContext, ReminderProvider } from './contexts/ReminderContext';

ReactDOM.render(
  <ReminderProvider>
    <ReminderContext.Consumer>
      { ({ reminders, clearReminders, addReminder, deleteReminder }) =>
        (<App clearReminders={ clearReminders } deleteReminder={ deleteReminder } addReminder={ addReminder } reminders={ reminders } />)
      }
    </ReminderContext.Consumer>
  </ReminderProvider>,
  document.getElementById('root')
);
registerServiceWorker();

src/components/App.js

import React, { Component } from 'react';
import PropTypes from 'prop-types';
import moment from 'moment';

class App extends Component {
  constructor(props) {
    super(props)
    this.state = {
      text: '',
      dueDate: ''
    };
  }

  addReminder() {
    this.props.addReminder(this.state.text, this.state.dueDate);
  }

  deleteReminder(id) {
    this.props.deleteReminder(id);
  }

  clearReminders() {
    this.props.clearReminders();
  }

  renderReminders() {
    const { reminders } = this.props;
    return (
      <ul className="list-group col-sm-8 mt-2">
        {
          reminders.map(reminder => {
            return (
              <li key={ reminder.id } className="list-group-item">
                <div className="list-item">
                  <div>{ reminder.text }</div>
                  <div><em>{ moment(new Date(reminder.dueDate)).fromNow() }</em></div>
                </div>
                <div
                  className="list-item delete-button"
                  onClick={ () => this.deleteReminder(reminder.id) }
                >
                  &#x2715;
                </div>
              </li>
            );
          })
        }
      </ul>
    );
  }

  render() {
    return (
      <div className="App">
        <div className="title">Reminder Pro</div>

        <div className="form-inline">
          <div className="form-group mr-2">
            <input
              type="text"
              className="form-control mr-2"
              placeholder="I have to..."
              onChange={ (event) => this.setState({text: event.target.value}) }
            />
            <input
              type="datetime-local"
              className="form-control"
              onChange={ (event) => this.setState({dueDate: event.target.value}) }
            />
          </div>
          <button
            type="button"
            className="btn btn-success"
            onClick={ () => this.addReminder() }
          >
            Add Reminder
          </button>
        </div>
        { this.renderReminders() }
        <div 
          className="btn btn-danger mt-3"
          onClick={ () => this.clearReminders() }
        >
          Clear Reminders
        </div>
      </div>
    );
  }
}

App.propTypes = {
  reminders: PropTypes.array.isRequired,
  addReminder: PropTypes.func.isRequired,
  deleteReminder: PropTypes.func.isRequired,
  clearReminders: PropTypes.func.isRequired
}

export default App;