我已经思考了一段时间,但是仍无法解决问题,希望能得到任何帮助。
我正在使用React与Redux Toolkit,但我在尝试从UI中删除一个“todo”时遇到了困难,即使Redux的响应是按预期进行的。在Redux Developer Tools中removeTodo按预期工作,从todos数组状态中删除了一个todo,但React没有跟随,因此我的UI也没有相应更改。我的addTodo动作在React和Redux中都按预期工作。
当我点击调用removeTodo分派的按钮时,当前代码给我提供了以下错误提示:
TypeError: Cannot read property 'length' of undefined
App
C:/Users/joeee/Documents/redux-middleware/src/app/App.js:13
10 |
11 | return (
12 | <div style={divStyles}>
> 13 | <TodosForm />
| ^ 14 | {todos.length > 0 && <TodoList />}
15 | </div>
16 | )
View compiled
▶ 19 stack frames were collapsed.
需要翻译的内容:
需要注意的是,只有当我的todos数组状态长度大于0时,我才在我的TodoList组件中进行渲染,因为我不希望在没有待办事项时渲染该组件。我对React和Redux还很陌生,也许有一个非常简单的解决方案,但是从我能够理解的来看,当调用removeTodo时,todos数组状态被完全删除,而不仅仅是返回那些与传入的id不相等的id。这就是为什么我认为我得到的错误告诉我无法读取未定义的.length,因为现在我的todos状态为空。
我取消了对TodoList进行渲染所需的todos.length大于0的要求,但然后我收到了错误,即在TodoList中无法读取未定义的.map(我的todos状态),这对我来说证实了我的整个todos状态似乎正在被删除。
这是我的todosSlice:
import { createSlice } from '@reduxjs/toolkit';
export const todosSlice = createSlice({
name: 'todos',
initialState: {
todos: [],
},
reducers: {
addTodo: (state, action) => {
const { id, task } = action.payload;
state.todos.push({ id, task })
},
removeTodo: (state, action) => {
// console.log(state.todos);
const { id } = action.payload;
// console.log(id);
return state.todos.filter(item => item.id !== id);
}
},
});
export const selectTodos = state => state.todos.todos;
export const { addTodo, removeTodo } = todosSlice.actions;
export default todosSlice.reducer;
App.js:
import React from 'react';
import { useSelector } from 'react-redux';
import TodosForm from '../components/TodosForm';
import TodoList from '../components/TodoList';
import { selectTodos } from '../features/todosSlice';
export const App = () => {
const todos = useSelector(selectTodos);
// console.log(todos.length);
return (
<div style={divStyles}>
<TodosForm />
{todos.length > 0 && <TodoList />}
</div>
)
}
export default App;
TodoList.js
import React from 'react';
import { useSelector } from 'react-redux';
import { selectTodos } from '../features/todosSlice';
import Todos from './Todos';
const TodoList = () => {
const todos = useSelector(selectTodos);
// console.log(todos);
return (
<div style={divStyles}>
<h3 style={headerStyles}>Your Todos: </h3>
{todos.map(todo => <Todos key={todo.id} task={todo.task} id={todo.id} />)}
</div>
)
}
export default TodoList
Todos.js
import React from 'react';
import { useDispatch } from 'react-redux';
import { FontAwesomeIcon } from '@fortawesome/react-fontawesome'
import { faTrashAlt } from '@fortawesome/free-solid-svg-icons'
import { faEdit } from '@fortawesome/free-solid-svg-icons'
import { removeTodo } from '../features/todosSlice';
const Todos = ({ task, id }) => {
const dispatch = useDispatch();
const handleDeleteClick = () => {
dispatch(removeTodo({id: id}));
}
return (
<div style={divStyles}>
<li style={listStyles}>{task}</li>
<div>
<button className="faEditIcon" style={btnStyles}><FontAwesomeIcon icon={faEdit}/></button>
<button className="faDeleteIcon" style={btnStyles} onClick={handleDeleteClick}><FontAwesomeIcon icon={faTrashAlt}/></button>
</div>
</div>
)
}
export default Todos;
还有我的store.js
import { configureStore } from '@reduxjs/toolkit';
import todosSliceReducer from '../features/todosSlice';
export default configureStore({
reducer: {
todos: todosSliceReducer,
},
});
removeTodo
reducer 返回的是新的state.todos
数组作为整个状态,而不是修改state.todos
。 - Code-Apprentice