Question

TLDR：如何将已经映射的json数组传递回一个状态。我希望“喜欢”处于一个州内。

，例如这样调用

<Like like={id} likes={this.state.likes} />

不喜欢

<Like like={id} likes={Likes.length} />

我需要添加一个计数器来增加点击计数，这就是为什么需要动态地增加点击计数的原因。

这是数组的直观表示。

我正在这样做以便在PostList.js中获取它

{this.getLikes(post.Likes)}

在函数im中执行此操作

  getLikes = (count) =>  {
        const myLikes = count.forEach( (like) => like.length);

        this.setState({
            likes: myLikes
        })

    }

喜欢的状态将在名为myLikes的道具中传递给postItem组件。

myLikes={this.state.likes}

在 PostItem.js

内

它会像这样被引用

<Like like={id} likes={myLikes} />

但是出现此错误。

已超过最大更新深度。当一个组件发生这种情况重复调用componentWillUpdate内的setState或 componentDidUpdate。 React将嵌套更新的数量限制为防止无限循环。

这是详细代码

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 PostItem from './PostItem';
const Styles = {
    myPaper: {
        margin: '20px 0px',
        padding: '20px'
    }
}
class PostList extends Component{
    constructor(props){
        super(props);
        this.state ={
            title: '',
            likes:[]
        }
    }


    getLikes = (count) =>  {
        const myLikes = count.forEach( (like) => like.length);

        this.setState({
            likes: myLikes
        })

    }
    render(){
        const {posts} = this.props;
        return (
            <div>
                {posts.map((post, i) => (

                    <Paper key={post.id} style={Styles.myPaper}>
                             {this.getLikes(post.Likes)}
                    {/* {...post} prevents us from writing all of the properties out */}
                        <PostItem  
                             myLikes={this.state.likes}                 
                             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) => ({

})
const mapDispatchToProps = (dispatch) => ({

});
export default connect(mapStateToProps, mapDispatchToProps)(PostList);

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) => ({

})
const mapDispatchToProps = (dispatch) => ({

});
export default connect(mapStateToProps, mapDispatchToProps)(PostItem);

还有更多信息

Posts.js

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, 
  }
  async componentWillMount(){
    await this.props.GetPosts();

    const thesePosts = await this.props.myPosts
    const myPosts2 = await thesePosts
    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));

尝试将映射的json数据传递到状态时，超出了最大更新深度

0 个答案: