Reactnative 如何在 React native redux 的 reducer 中向数组添加元素

发布于03月20日

如何在reducer中的redux状态数组arr[]中添加元素？

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
    }
}

推荐答案

由于这个问题被大量曝光:

如果你正在寻找这个问题的答案，很有可能是you are following a very outdated Redux tutorial.

官方建议(自2019年起)增加到use the official Redux Toolkit to write modern Redux code.

除此之外，这将消除字符串动作常量，并为您生成动作创建者.

它还将使用一些方法，允许您只在由createReducer或createSlice创建的约简中编写变异逻辑，所以首先是there is no need to write immutable code in Reducers in modern Redux.

请遵循official Redux tutorials而不是第三方教程，以始终获得有关良好Redux实践的最新信息，并向您展示如何在不同的常见场景中使用Redux工具包.

相比之下，在现代Redux中

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;