ReactJS - 列出费用

打开 ExpenseEntryItemList.js 并从 redux 库导入 connect。

import { connect } from 'react-redux';

接下来，导入 addExpenseList 和 deleteExpense 操作。

import { getExpenseList, deleteExpense } from '../actions/expenseActions';

接下来，添加带有 props 的构造函数。

constructor(props) { 
   super(props); 
}

接下来，在 componentDidMount() 生命周期中调用 getExpenseList。

componentDidMount() { 
   this.props.getExpenseList(); 
}

接下来，编写一个方法来处理删除费用选项。

handleDelete = (id,e) => { 
   e.preventDefault(); 
   this.props.deleteExpense(id); 
}

现在，让我们编写一个函数 getTotal 来计算总费用。

getTotal() {
   let total = 0;
   if (this.props.expenses != null) {
      for (var i = 0; i < this.props.expenses.length; i++) {
         total += this.props.expenses[i].amount
      }
   }
   return total;
}

接下来，更新 render 方法并列出费用项目。

render() {
   let lists = [];

   if (this.props.expenses != null) {
      lists = this.props.expenses.map((item) =>
         <tr key={item.id}>
            <td>{item.name}</td>
            <td>{item.amount}</td>
            <td>{new Date(item.spendDate).toDateString()}</td>
            <td>{item.category}</td>
            <td><a href="#"
               onClick={(e) => this.handleDelete(item.id, e)}>Remove</a></td>
         </tr>
      );
   }
   return (
      <div>
         <table>
            <thead>
               <tr>
                  <th>Item</th>
                  <th>Amount</th>
                  <th>Date</th>
                  <th>Category</th>
                  <th>Remove</th>
               </tr>
            </thead>
            <tbody>
               {lists}
               <tr>
                  <td colSpan="1" style={{ textAlign: "right" }}>Total Amount</td>
                  <td colSpan="4" style={{ textAlign: "left" }}>
                     {this.getTotal()}
                  </td>
               </tr>
            </tbody>
         </table>
      </div>
   );
}

接下来，编写 mapStateToProps 和 mapDispatchToProps 方法。

const mapStateToProps = state => {
   return {      
      expenses: state.data
   };
};
const mapDispatchToProps = {
   getExpenseList,
   deleteExpense
};

在这里，我们将费用项目从 redux 存储映射到 expenses 属性，并将 distpatcher、getExpenseList 和 deleteExpense 附加到组件属性。

最后，使用 connect api 将组件连接到 Redux 存储。

export default connect(
    mapStateToProps,
    mapDispatchToProps
)(ExpenseEntryItemList);

应用程序的完整源代码如下 −

import React from "react";
import { connect } from 'react-redux';
import { getExpenseList, deleteExpense } from '../actions/expenseActions';

class ExpenseEntryItemList extends React.Component {
   constructor(props) {
      super(props);
   }
   componentDidMount() {
      this.props.getExpenseList();
   }
   handleDelete = (id, e) => {
      e.preventDefault();
      this.props.deleteExpense(id);
   }
   getTotal() {
      let total = 0;
      if (this.props.expenses != null) {
         for (var i = 0; i < this.props.expenses.length; i++) {
            total += this.props.expenses[i].amount
         }
      }
      return total;
   }
   render() {
      let lists = [];
      if (this.props.expenses != null) {
         lists = this.props.expenses.map((item) =>
            <tr key={item.id}>
               <td>{item.name}</td>
               <td>{item.amount}</td>
               <td>{new Date(item.spendDate).toDateString()}</td>
               <td>{item.category}</td>
               <td><a href="#"
                  onClick={(e) => this.handleDelete(item.id, e)}>Remove</a>
               </td>
            </tr>
         );
      }
      return (
         <div>
            <table>
               <thead>
                  <tr>
                     <th>Item</th>
                     <th>Amount</th>
                     <th>Date</th>
                     <th>Category</th>
                     <th>Remove</th>
                  </tr>
               </thead>
               <tbody>
                  {lists}
                  <tr>
                     <td colSpan="1" style={{ textAlign: "right" }}>Total Amount</td>
                     <td colSpan="4" style={{ textAlign: "left" }}>
                        {this.getTotal()}
                     </td>
                  </tr>
               </tbody>
            </table>
         </div>
      );
   }
}
const mapStateToProps = state => {
   return {
      expenses: state.data
   };
};
const mapDispatchToProps = {
   getExpenseList,
   deleteExpense
};
export default connect(
   mapStateToProps,
   mapDispatchToProps
)(ExpenseEntryItemList);

接下来，使用 npm 命令为应用程序提供服务。

npm start

接下来，打开浏览器并在地址栏中输入 http://localhost:3000 并按 Enter。

reactjs_example.html