我正在做一个React Redux的例子;然而,我遇到了一个问题,得到下面的错误:
TypeError: this.props.tasks.map不是一个函数(了解更多)
我已经尝试了很多事情,我似乎不能理解为什么这是不工作。我相信这是当allReducers从tasks函数映射任务时。我来回修正了这个错误,但它会抱怨它是未定义的。我会解决这个问题,然后循环回到这个问题。任何帮助都会很感激。我肯定我犯了一个小错误。以下是我的以下文件
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
task-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);
reducer-tasks.js
const initialState = {
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"
}
]
}
export function Tasks (state = initialState, action) {
switch (action.type) {
case 'ADD_TASK':
return Object.assign({}, state, {
tasks: [
...state.tasks,
{
description: action.text,
status: action.status
}
]
})
break;
case 'EDIT_TASK':
return action.payload;
break;
case 'DELETE_TASK':
return Object.assign({}, state, {
status: action.status
})
break;
}
return state;
}
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
}
};
这是因为函数'map'只能用于数组,不能用于对象。
如果你在task-board.js的渲染函数中打印出this.props.tasks,你会看到它是一个包含任务数组的OBJECT,而不是实际的任务数组本身。
修复这个很简单,而不是:
return this.props.tasks.map((task) => {
return this.props.tasks.tasks.map((task) => {
那么就可以了
根据你们的减速器组成,你们的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"
}
]
如果您试图在获取数据之前呈现,请检查服务器代码。如果是这种情况,redux/react抛出.map不是一个函数。
总是获取数据,使用中间件,然后尝试从服务器渲染客户端。
我在redux中遇到了同样的问题,问题是我试图在渲染客户端