React Redux Reducer：'this.props.tasks.map不是函数'错误
我正在制作一个React Redux示例;然而，我遇到了一个问题，得到的错误如下：React Redux Reducer：'this.props.tasks.map不是函数'错误
TypeError: this.props.tasks.map is not a function [Learn More]
我已经尝试了很多东西，我似乎无法理解为什么这是行不通的。我相信这是allReducers映射Tasks功能任务的时候。我已经解决了这个错误，但它会抱怨它是未定义的。我会解决这个问题并回到这个问题。任何帮助，将不胜感激。我确定我犯了一个简单的错误。下面是我的以下文件
App.js
import React from 'react';
import TaskBoard from "../containers/task-board";
require('../../scss/style.scss');
const App =() => (
<div>
<h2>Task List</h2>
<hr />
<TaskBoard/>
</div>
);
export default App;index.js
import {combineReducers} from 'redux';
import {Tasks} from './reducer-tasks';
const allReducers = combineReducers({
tasks: Tasks
});
export default allReducers任务board.js
import React, {Component} from 'react';
import {bindActionCreators} from 'redux';
import {connect} from 'react-redux';
import {deleteTaskAction} from '../actions/ActionIndex';
import {editTaskAction} from '../actions/ActionIndex';
class TaskBoard extends Component {
renderList() {
return this.props.tasks.map((task) => {
if(task.status == "pending"){
return (<li key={task.id}>
{task.id} {task.description}
<button type="button">Finish</button>
<button type="button">Edit</button>
<button onClick={() => this.props.deleteTask(task)} type="button">Delete</button>
</li>
);
}
});
}
render() {
if (!this.props.tasks) {
console.log(this.props.tasks);
return (<div>You currently have no tasks, please first create one...</div>);
}
return (
<div>
{this.renderList()}
</div>
);
}
}
function mapStateToProps(state) {
return {
tasks: state.tasks
};
}
function matchDispatchToProps(dispatch){
return bindActionCreators(
{
deleteTask: deleteTaskAction,
editTask: editTaskAction
}, dispatch)
}
export default connect(mapStateToProps,matchDispatchToProps)(TaskBoard);减速器tasks.js
const initialState = {
\t tasks: [
{
id: 1,
description: "This is a task",
status: "pending"
},
{
id: 2,
description: "This is another task",
status: "pending"
},
{
id: 3,
description: "This is an easy task",
status: "pending"
}
\t ]
}
export function Tasks (state = initialState, action) {
switch (action.type) {
case 'ADD_TASK':
return Object.assign({}, state, {
\t tasks: [
\t \t ...state.tasks,
\t \t {
\t \t \t description: action.text,
\t \t \t status: action.status
\t \t }
\t ]
})
break;
case 'EDIT_TASK':
return action.payload;
break;
case 'DELETE_TASK':
return Object.assign({}, state, {
\t status: action.status
})
break;
}
return state;
}的actionIndex。 JS
export const addTaskAction = (task) => {
return {
type: 'ADD_TASK',
text: "Here is a sample description",
status: "pending"
}
};
export const deleteTaskAction = (task) => {
return {
type: 'DELETE_TASK',
status: "deleted"
}
};
export const editTaskAction = (task) => {
return {
type: 'EDIT_TASK',
payload: task
}
};
这是因为功能 '地图' 只能用于数组，而不是对象。
如果你在task-board.js的渲染函数中打印出this.props.tasks，你会发现它是一个OBJECT，它包含任务数组，而不是实际任务数组本身。
因此，要解决这个问题是很容易的，而不是：
return this.props.tasks.map((task) => {
它
return this.props.tasks.tasks.map((task) => {
然后它
根据你的减速机组成，你initialState应该是：
const initialState = [
{
id: 1,
description: "This is a task",
status: "pending"
},
{
id: 2,
description: "This is another task",
status: "pending"
},
{
id: 3,
description: "This is an easy task",
status: "pending"
}
]
我明白你的意思。我现在已经改变它，但我仍然得到同样的错误。 TypeError：this.props.tasks.map不是函数 – Potion
好的，谢谢我会记住在尝试映射之前打印该变量以查看它的对象或数组。感谢您的巧妙手段。同样在delete_task中，我如何返回，以便将“待处理”状态更改为“已删除”？ – Potion
至于你如何更新状态从待处理状态删除？ – Jayce444
是的，这是正确的。 – Potion