用户喜欢帖子时如何更新道具状态？
当用户点击喜欢时，道具需要自动更新。
当前，用户可以喜欢一个帖子，并且只有在页面刷新时，我才能看到更新的点赞次数，这显示在
上 {this.props.likeCount}
哪个组件生命周期最适合在不刷新页面的情况下查看更新的道具？此应用程序正在使用redux。
Like.js
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 { getLikeCount} from '../actions/';
class Like extends Component{
constructor(props){
super(props);
this.state = {
likes: null
}
}
getLikes = (id) => {
// console.log(id);
this.props.getLikeCount(id)
console.log(this.props.likeCount)
}
render(){
return(
<div style={{float:'right', fontSize: '1.5em', color:'tomato'}} >
<i style={{ marginRight: '140px'}} className="fa fa-heart-o">
<span style={{ marginLeft: '6px'}}>
<a href="#" onClick={this.props.like}>Like </a>
{this.getLikes(this.props.postId)}
</span>
{/* gets the like counts */}
{this.props.likeCount}
</i>
</div>
)
}
}
const mapStateToProps = (state) => ({
isEditingId: state.post.isEditingId,
likeCount:state.post.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.
getLikeCount: (id) => dispatch(getLikeCount(id)),
// Pass id to the DeletePost functions.
});
export default connect(mapStateToProps, mapDispatchToProps)(Like);
Actions.js
export const getLikeCount = (id) => {
return (dispatch, getState) => {
return Axios.get(`/api/posts/likes/count/${id}`)
.then( (res) => {
const data = res.data
console.log(data);
dispatch({type: GET_LIKES_COUNT, data})
})
}
}
减速器
import { GET_LIKES_COUNT} from '../actions/';
const initialState = {
post: [],
postError: null,
posts:[],
isEditing:false,
isEditingId:null,
likes:[],
postId:null
}
export default (state = initialState, action) => {
switch (action.type) {
case GET_LIKES_COUNT:
// console.log(action.data)
return({
...state,
likes:action.data
})
default:
return state
}
}
修改（即时获取无限的无限循环）
答案 0 :(得分：1)
反应哲学基于对更改的删除刷新页面。 所以忘了在所有react应用中刷新。
您可以在组件中更改如下代码：
from pyspark.sql.functions import when
df = spark\
.createDataFrame([\
(70, 'wa'),\
(50, 'mn'),\
(20, 'fl')],\
["tech", "state"])
df\
.select("*", when(df.tech == 50, 1)\
.otherwise(0)\
.alias("tech"))\
.show()
+----+-----+----+
|tech|state|tech|
+----+-----+----+
| 70| wa| 0|
| 50| mn| 1|
| 20| fl| 0|
+----+-----+----+
并付诸行动：
handleAddUpVote = ()=> this.props.dispatch(addUpVote())
return(
<div onClick={this.handleAddUpVote}> sth </div>
)
最后，更换您的减速器：
const ADD_UP_VOTE = "ADD_UP_VOTE";
const addUpVote = ({type: ADD_UP_VOTE});
export {ADD_UP_VOTE, addUpVote}
答案 1 :(得分：1)
将代码更新为以下代码。
GET_LIKES_COUNT处理api操作，以获取帖子的喜欢次数。
没有它，它将在渲染时始终设置为“ 0个赞”。
ADD_LIKE动作提供了无需刷新页面即可更新状态的功能。（我知道他们在响应时称呼它为更具体的术语，也许会重新呈现）更新状态而无需重新呈现组件以及最重要的部分，即对后端进行api调用以使用户喜欢帖子。我们将likes设置为0，以便可以更新状态，并可以不刷新而对其进行更新。
感谢@novonimo的帮助。
减速器
import { GET_LIKES_COUNT, ADD_LIKE} from '../actions/';
const initialState = {
post: [],
postError: null,
posts:[],
isEditing:false,
isEditingId:null,
likes:0,
postId:null
}
export default (state = initialState, action) => {
switch (action.type) {
// get number of likes from api
case GET_LIKES_COUNT:
// console.log(action.data)
return({
...state,
likes:action.data
})
case ADD_LIKE:
return({
...state,
likes: state.likes + 1
})
default:
return state
}
}
操作
export const postLike = (id) => {
return (dispatch) => {
// console.log(userId);
return Axios.post('/api/posts/like', {
postId: id
}).then( (like) => {
dispatch({type: ADD_LIKE})
// console.log('you have liked this', like)
}).catch( (err)=> {
console.log('there seem to be an error', err);
})
}
}
export const getLikeCount = (id) => {
return (dispatch, getState) => {
return Axios.get(`/api/posts/likes/count/${id}`)
.then( (res) => {
const data = res.data
console.log(data);
dispatch({type: GET_LIKES_COUNT, data})
})
}
}
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, getLikeCount, postLike} 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,
}
}
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);
}
}
clickLike = (id) => () => {
this.props.postLike(id);
}
render(){
const {title, id, userId, removePost, createdAt, post_content, username, editForm, isEditing, editChange, myTitle, postUpdate, likes} = 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="p">
{post_content}
<h5>
by: {username}</h5>
<Typography color="textSecondary">{moment(createdAt).calendar()}</Typography>
<Like like={this.clickLike(id)} postId={id}/>
</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)),
getLikeCount: (id) => dispatch(getLikeCount(id)),
postLike: (id) => dispatch( postLike(id))
// Pass id to the DeletePost functions.
});
export default connect(null, mapDispatchToProps)(PostItem);
Like.js
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 { getLikeCount} from '../actions/';
class Like extends Component{
constructor(props){
super(props);
this.state = {
likes: null
}
}
getLikes = (id) => {
// console.log(id);
this.props.getLikeCount(id)
console.log(this.props.likeCount)
}
render(){
return(
<div style={{float:'right', fontSize: '1.5em', color:'tomato'}} >
<i style={{ marginRight: '140px'}} className="fa fa-heart-o">
<span style={{ marginLeft: '6px'}}>
<a href="#" onClick={this.props.like}>Like </a>
{this.getLikes(this.props.postId)}
</span>
{/* gets the like counts */}
{this.props.likeCount}
</i>
</div>
)
}
}
const mapStateToProps = (state) => ({
isEditingId: state.post.isEditingId,
likeCount:state.post.likes
})
const mapDispatchToProps = (dispatch) => ({
getLikeCount: (id) => dispatch(getLikeCount(id)),
// Pass id to the DeletePost functions.
});
export default connect(mapStateToProps, mapDispatchToProps)(Like);