如何在还原器中的redux状态的数组arr[]
中添加元素?我正在这样做 -
import {ADD_ITEM} from '../Actions/UserActions'
const initialUserState = {
arr:[]
}
export default function userState(state = initialUserState, action)
{
console.log(arr);
switch (action.type)
{
case ADD_ITEM:
return {
...state,
arr: state.arr.push([action.newItem])
}
default:
return state
}
}
两个不同的选项将项目添加到不突变的数组
case ADD_ITEM :
return {
...state,
arr: [...state.arr, action.newItem]
}
或
case ADD_ITEM :
return {
...state,
arr: state.arr.concat(action.newItem)
}
push
不返回数组,而是它的长度(文档),因此您正在做的是用其长度替换数组,从而失去了对其所拥有的唯一引用。尝试以下操作:
import {ADD_ITEM} from '../Actions/UserActions'
const initialUserState = {
arr:[]
}
export default function userState(state = initialUserState, action){
console.log(arr);
switch (action.type){
case ADD_ITEM :
return {
...state,
arr:[...state.arr, action.newItem]
}
default:return state
}
}
如果您需要插入数组中的特定位置,则可以执行此操作:
case ADD_ITEM :
return {
...state,
arr: [
...state.arr.slice(0, action.pos),
action.newItem,
...state.arr.slice(action.pos),
],
}
因为这个问题得到了很多曝光:
如果您正在寻找这个问题的答案,则很有可能您正在遵循一个非常过时的redux教程。
官方建议(自2019年起)是使用官方的Redux工具包编写现代Redux代码。
除其他外,它将消除字符串动作常数并为您生成动作创建者。
它还将采用允许您在createReducer
或createSlice
创建的还原器中写突变逻辑的方法,因此无需首先在现代Redux 中编写不可能的代码。
请遵循官方的Redux教程,而不是第三方教程,以始终获取有关Redux实践的最新信息,还将向您展示如何在不同的常见场景中使用Redux Toolkit。
进行比较,在现代redux中,这看起来像
const userSlice = createSlice({
name: "user",
initialState: {
arr:[]
},
reducers: {
// no ACTION_TYPES, this will internally create a type "user/addItem" that you will never use by hand. You will only see it in the devTools
addItem(state, action) {
// you can use mutable logic in createSlice reducers
state.arr.push(action.payload)
}
}
})
// autogenerated action creators
export const { addItem } = slice.actions;
// and export the final reducer
export default slice.reducer;
如果要组合两个阵列,一个接一个阵列,则可以使用
//initial state
const initialState = {
array: [],
}
...
case ADD_ARRAY :
return {
...state,
array: [...state.array, ...action.newArr],
}
//if array = [1,2,3,4]
//and newArr = [5,6,7]
//then updated array will be -> [1,2,3,4,5,6,7]
...
此传播操作员(...)迭代数组元素并存储在数组中[]或在数组中传播元素,您可以简单地使用&quot&quot&quot' for 循环"或与任何其他循环。
嵌套数组的最简单解决方案是 concat()
:
case ADD_ITEM:
state.array = state.array.concat(action.paylod)
return state
concat()
吐出更新的数组,而无需突变状态。只需将数组设置为concat()
的输出并返回状态。
我有一个样本
import * as types from '../../helpers/ActionTypes';
var initialState = {
changedValues: {}
};
const quickEdit = (state = initialState, action) => {
switch (action.type) {
case types.PRODUCT_QUICKEDIT:
{
const item = action.item;
const changedValues = {
...state.changedValues,
[item.id]: item,
};
return {
...state,
loading: true,
changedValues: changedValues,
};
}
default:
{
return state;
}
}
};
export default quickEdit;
这对我有用
//Form side
const handleSubmit = (e) => {
e.preventDefault();
let Userdata = { ...userdata, id: uuidv4() };
dispatch(setData(Userdata));
};
//Reducer side
const initialState = {
data: [],
};
export const dataReducer = (state = initialState, action) => {
switch (action.type) {
case ActionTypes.SET_DATA:
return { ...state, data: [...state.data, action.payload] };
default:
return state;
}
};
对我来说,我的redux商店看起来像这样:
export const cartSlice = createSlice({
name: "cart",
initialState: {
itemsAdded: [],
total: 0,
},
reducers: {
addItem: (state, action) => {action.payload };
state.itemsAdded.push(action.payload);
},
},
});
简单地我添加到我的数组itemsAdded
, state.itemsAdded.push(action.payload);