【发布时间】：2019-09-16 18:54:23
【问题描述】：
TLDR：如何在 reducer 中更新数组对象
我需要一些帮助来了解如何在触发操作后更新我的帖子数据的点赞计数值，以及可能的工作逻辑。
从一个动作中获取帖子，作为帖子属性传递和映射。理想情况下，它应该在 upvote 上创建一个新的 likes 对象
用户可以点击喜欢，并在后端添加一个喜欢。哪个好。 前端需要将当前值投票赞成 +1，但是当前逻辑不起作用。
用当前逻辑得到这个错误
似乎有一个错误 TypeError: Invalid attempt to spread 不可迭代的实例
console.log(index) 为用户点击的任何帖子呈现点赞数。
例如喜欢
20
我将无法使用状态，我需要在 redux 中执行此操作。
https://i.stack.imgur.com/1N0Nh.png
这是帖子结构
{
"id": 5,
"title": "React Interview Questiossssnsdd",
"post_content": "ssss",
"username": "blueowl",
"createdAt": "2019-04-26T09:38:10.324Z",
"updatedAt": "2019-04-26T18:55:39.319Z",
"userId": 1,
"Likes": [
{
"id": 131,
"like": true,
"createdAt": "2019-04-26T12:20:58.251Z",
"updatedAt": "2019-04-26T12:20:58.251Z",
"userId": 1,
"postId": 5
},
{
"id": 152,
"like": true,
"createdAt": "2019-04-26T14:01:13.347Z",
"updatedAt": "2019-04-26T14:01:13.347Z",
"userId": 1,
"postId": 5
},
{
"id": 153,
"like": true,
"createdAt": "2019-04-26T14:01:46.739Z",
"updatedAt": "2019-04-26T14:01:46.739Z",
"userId": 1,
"postId": 5
},...
点赞结构示例
[
{
"id": 182,
"like": true,
"createdAt": "2019-04-27T11:05:05.612Z",
"updatedAt": "2019-04-27T11:05:05.612Z",
"userId": 1,
"postId": 5
},
{
"id": 178,
"like": true,
"createdAt": "2019-04-27T10:44:49.311Z",
"updatedAt": "2019-04-27T10:44:49.311Z",
"userId": 1,
"postId": 5
},
{
"id": 179,
"like": true,
"createdAt": "2019-04-27T10:45:27.380Z",
"updatedAt": "2019-04-27T10:45:27.380Z",
"userId": 1,
"postId": 5
},
{
"id": 180,
"like": true,
"createdAt": "2019-04-27T10:46:44.260Z",
"updatedAt": "2019-04-27T10:46:44.260Z",
"userId": 1,
"postId": 5
},
减速器
const initialState = {
post: [],
postError: null,
posts:[],
isEditing:false,
isEditingId:null,
likes:[],
someLike:[],
postId:null
}
export default (state = initialState, action) => {
switch (action.type) {
case GET_POSTS:
console.log(action.data)
return {
...state,
posts: action.data, // maps posts fine,
}
case ADD_LIKE:
console.log(action.id) // renders post id
// console.log(state.posts) // logs posts array
console.log(state.posts)
const index = state.posts.find((post) => post.id === action.id).Likes.length
console.log(index); // gets likes length for the corresponding id to whatever post that has been clickd
// renders 5 or 3 (their is currently 2 posts)
// honestly don't what im doing below this line of code but should make a new like object
return [
{
Likes: [
...state.posts.find((post) => post.id === action.id).Likes.length + 1,
action.newLikeObject
]
}
]
在此处显示更新计数
myLikes={post.Likes.length} // right here
render(){
const {posts} = this.props; // from reducer
return (
<div>
{posts.map(post => (
<Paper key={post.id} style={Styles.myPaper}>
<PostItem
myLikes={post.Likes.length} // right here
myTitle={this.state.title}
editChange={this.onChange}
editForm={this.formEditing}
isEditing={this.props.isEditingId === post.id}
removePost={this.removePost}
{...post}
/>
</Paper>
))}
</div>
);
}
}
额外信息
actions.js
export const postLike = (id) => {
return (dispatch) => {
// console.log(userId);
return Axios.post('/api/posts/like', {
postId: id
}).then( (like) => {
dispatch({type: ADD_LIKE, id})
// console.log('you have liked this', like)
}).catch( (err)=> {
console.log('there seem to be an error', err);
})
}
}
编辑
console.log(newState)
{
"post": [],
"postError": null,
"posts": [
{
"id": 5,
"title": "React Interview Questiossssnsdd",
"post_content": "ssss",
"username": "EliHood",
"createdAt": "2019-04-26T09:38:10.324Z",
"updatedAt": "2019-04-26T18:55:39.319Z",
"userId": 1,
"Likes": [
{
"id": 219,
"like": true,
"createdAt": "2019-04-27T15:54:03.841Z",
"updatedAt": "2019-04-27T15:54:03.841Z",
"userId": 1,
"postId": 5
},
{
"id": 189,
"like": true,
"createdAt": "2019-04-27T11:11:07.558Z",
"updatedAt": "2019-04-27T11:11:07.558Z",
"userId": 1,
"postId": 5
},
{
"id": 190,
"like": true,
"createdAt": "2019-04-27T11:12:09.599Z",
"updatedAt": "2019-04-27T11:12:09.599Z",
"userId": 1,
"postId": 5
},
....,
"isEditing": false,
"isEditingId": null,
"likes": [
77,
24
],
"someLike": [],
"postId": null
}
点赞组件
import React, { Component } from 'react';
import ReactDOM from 'react-dom'
import { FontAwesomeIcon } from '@fortawesome/react-fontawesome';
import { faCoffee, faAdjust } from '@fortawesome/free-solid-svg-icons';
import {connect} from 'react-redux';
import { postLike} from '../actions/';
class Like extends Component{
constructor(props){
super(props);
this.state = {
likes: null,
heart: false
}
}
// passes post id thats stored in PostItem.js
clickLike = (id) => {
this.props.postLike(id);
// toggles between css class
this.setState({
heart: !this.state.heart
})
}
render(){
return(
<div style={{float:'right', fontSize: '1.5em', color:'tomato'}} >
<i style={{ marginRight: '140px'}} className={this.state.heart ? 'fa fa-heart':'fa fa-heart-o' }>
<span style={{ marginLeft: '6px'}}>
<a href="#" onClick={() =>this.clickLike(this.props.like)}>Like</a>
</span>
{/* gets the like counts */}
<span style={{ marginLeft: '7px'}} >{this.props.likes} </span>
</i>
</div>
)
}
}
const mapStateToProps = (state) => ({
isEditingId: state.post.isEditingId,
})
const mapDispatchToProps = (dispatch) => ({
postLike: (id) => dispatch( postLike(id))
// Pass id to the DeletePost functions.
});
export default connect(mapStateToProps, mapDispatchToProps)(Like);
like 组件在这里传递为<Like like={id} likes={myLikes} />
PostItem.js
import React, { Component } from 'react';
import Paper from '@material-ui/core/Paper';
import Button from '@material-ui/core/Button';
import Typography from '@material-ui/core/Typography';
import moment from 'moment';
import Editable from './Editable';
import {connect} from 'react-redux';
import {UpdatePost, postLike, getCount} from '../actions/';
import Like from './Like';
import Axios from '../Axios';
const Styles = {
myPaper: {
margin: '20px 0px',
padding: '20px'
},
button:{
marginRight:'30px'
}
}
class PostItem extends Component{
constructor(props){
super(props);
this.state = {
disabled: false,
myId: 0,
likes:0
}
}
componentWillMount(){
}
onUpdate = (id, title) => () => {
// we need the id so expres knows what post to update, and the title being that only editing the title.
if(this.props.myTitle !== null){
const creds = {
id, title
}
this.props.UpdatePost(creds);
}
}
render(){
const {title, id, userId, removePost, createdAt, post_content, username, editForm, isEditing, editChange, myTitle, postUpdate, Likes, clickLike, myLikes} = this.props
return(
<div>
<Typography variant="h6" component="h3">
{/* if else teneray operator */}
{isEditing ? (
<Editable editField={myTitle ? myTitle : title} editChange={editChange}/>
): (
<div>
{title}
</div>
)}
</Typography>
<Typography component={'span'} variant={'body2'}>
{post_content}
<h5>by: {username} </h5>
{/* component span cancels out the cant be a decedent of error */}
<Typography component={'span'} variant={'body2'} color="textSecondary">{moment(createdAt).calendar()}</Typography>
{/* gets like counts */}
<Like like={id} likes={myLikes} />
</Typography>
{!isEditing ? (
<Button variant="outlined" type="submit" onClick={editForm(id)}>
Edit
</Button>
):(
// pass id, and myTitle which as we remember myTitle is the new value when updating the title
<div>
<Button
disabled={myTitle.length <= 3}
variant="outlined"
onClick={this.onUpdate(id, myTitle)}>
Update
</Button>
<Button
variant="outlined"
style={{marginLeft: '0.7%'}}
onClick={editForm(null)}>
Close
</Button>
</div>
)}
{!isEditing && (
<Button
style={{marginLeft: '0.7%'}}
variant="outlined"
color="primary"
type="submit"
onClick={removePost(id)}>
Remove
</Button>
)}
</div>
)
}
}
const mapStateToProps = (state) => ({
isEditingId: state.post.isEditingId,
})
const mapDispatchToProps = (dispatch) => ({
// pass creds which can be called anything, but i just call it credentials but it should be called something more
// specific.
UpdatePost: (creds) => dispatch(UpdatePost(creds)),
postLike: (id) => dispatch( postLike(id)),
// Pass id to the DeletePost functions.
});
export default connect(mapStateToProps, mapDispatchToProps)(PostItem);
Posts.js（主父级）
import React, { Component } from 'react';
import PostList from './PostList';
import {connect} from 'react-redux';
import { withRouter, Redirect} from 'react-router-dom';
import {GetPosts} from '../actions/';
const Styles = {
myPaper:{
margin: '20px 0px',
padding:'20px'
}
,
wrapper:{
padding:'0px 60px'
}
}
class Posts extends Component {
state = {
posts: [],
loading: true,
isEditing: false,
// likes:[]
}
async componentWillMount(){
await this.props.GetPosts();
const thesePosts = await this.props.myPosts
const myPosts2 = await thesePosts
// const filtered = myPosts2.map((post) => post.Likes )
// const likesCount = filtered.map( (like) => like.length)
this.setState({
posts: myPosts2,
loading:false
})
}
render() {
const {loading} = this.state;
const { myPosts} = this.props
if (!this.props.isAuthenticated) {
return (<Redirect to='/signIn' />);
}
if(loading){
return "loading..."
}
return (
<div className="App" style={Styles.wrapper}>
<h1> Posts </h1>
<PostList posts={this.state.posts}/>
</div>
);
}
}
const mapStateToProps = (state) => ({
isAuthenticated: state.user.isAuthenticated,
myPosts: state.post.posts,
})
const mapDispatchToProps = (dispatch, state) => ({
GetPosts: () => dispatch( GetPosts())
});
export default withRouter(connect(mapStateToProps,mapDispatchToProps)(Posts));
PostList.js
import React, { Component } from 'react';
import Paper from '@material-ui/core/Paper';
import Button from '@material-ui/core/Button';
import Typography from '@material-ui/core/Typography';
import moment from 'moment';
import {connect} from 'react-redux';
import {DeletePost, postLike, UpdatePost,EditChange, GetPosts, getCount, DisableButton} from '../actions/';
import PostItem from './PostItem';
import _ from 'lodash';
const Styles = {
myPaper: {
margin: '20px 0px',
padding: '20px'
}
}
class PostList extends Component{
constructor(props){
super(props);
this.state ={
title: '',
loading:true,
posts:[],
}
}
componentWillMount(){
this.props.GetPosts();
const ourPosts = this.props.myPosts
this.setState({
posts: ourPosts,
loading:false
})
console.log(this.state.posts)
}
componentWillReceiveProps(nextProps) {
const hasNewLike = false;
if(this.state.posts && this.state.posts.length) {
for(let index=0; index < nextProps.myPosts.length; index++) {
if(nextProps.myPosts[index].Likes.length !=
this.state.posts[index].Likes.length) {
hasNewLike = true;
}
}
}
if(hasNewLike) {
this.setState({posts: nextProps.myPosts}); // here we are updating the posts state if redux state has updated value of likes
}
console.log(nextProps.myPosts)
}
// Return a new function. Otherwise the DeletePost action will be dispatch each
// time the Component rerenders.
removePost = (id) => () => {
this.props.DeletePost(id);
}
onChange = (e) => {
e.preventDefault();
this.setState({
title: e.target.value
})
}
formEditing = (id) => ()=> {;
this.props.EditChange(id);
}
render(){
// const {posts, ourLikes, likes} = this.props;
// console.log(posts)
// console.log(this.props.ourLikes);
return (
<div>
{this.state.posts.map(post => (
<Paper key={post.id} style={Styles.myPaper}>
<PostItem
myLikes={post.Likes.length} // right here
myTitle={this.state.title}
editChange={this.onChange}
editForm={this.formEditing}
isEditing={this.props.isEditingId === post.id}
removePost={this.removePost}
{...post}
/>
</Paper>
))}
</div>
);
}
}
const mapStateToProps = (state) => ({
isEditingId: state.post.isEditingId,
myPosts: state.post.posts,
// ourLikes: state.post.likes // reducer likes
})
const mapDispatchToProps = (dispatch) => ({
// pass creds which can be called anything, but i just call it credentials but it should be called something more
// specific.
EditChange: (id) => dispatch(EditChange(id)),
UpdatePost: (creds) => dispatch(UpdatePost(creds)),
postLike: (id) => dispatch( postLike(id)),
GetPosts: () => dispatch( GetPosts()),
// Pass id to the DeletePost functions.
DeletePost: (id) => dispatch(DeletePost(id))
});
export default connect(mapStateToProps, mapDispatchToProps)(PostList);
【问题讨论】：
标签： reactjs redux react-redux