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Reactjs handleclick binding in a nested map not working

I am writing a simple blog component in React. The component get the post from a second file and renders the content and the hashtags with map (in particular two nested map). I was trying to create a part in which the hashtag are highlighted when clicked, and hence I was following the snippet of the answer to this question. The fact is that it is not working and in particular what it is not working is the binding through bind (checked with console.log output)
class Blog extends React.Component {
state= {
open: {}
}
handleClick = (k) => {
let linkOpenState = true;
if (this.state.open.hasOwnProperty(k)) {
linkOpenState = !this.state.open[k];
}
this.setState({ open: { [k]: linkOpenState } })
}
render(){
return(
posts.map(i=>(
<div class="box">
<article class="media">
<div class="media-content">
<div class="content">
<h1 class="title">{i.title}</h1>
<p>
{i.content}
</p>
</div>
<div class="tags">
{i.hash.map(k=>(<span id={k} onClick={this.handleClick.bind(this,k)} class={this.state.open[k]? "tag is-primary" : "tag"} >{k}</span>))}
</div>
</div>
</article>
</div>))
)
}
}
export default Blog
Anyone has an idea of what is wrong there? Is it the nested map a problem for the bind?

React expects a single element as a return. You can solve this by wrapping the return in a fragment as <React.Fragment> or <>.
Also, you don't need to bind an arrow function(handleClick when mapping i.hash).
render(){
return(
<>
posts.map(i=>(
<div class="box">
<article class="media">
<div class="media-content">
<div class="content">
<h1 class="title">{i.title}</h1>
<p>
{i.content}
</p>
</div>
<div class="tags">
{i.hash.map(k=>(<span key={k} id={k} onClick={() => this.handleClick(k)} class={this.state.open[k]? "tag is-primary" : "tag"} >{k}</span>))}
</div>
</div>
</article>
</div>))
</>)}}

You don't need to bind the arrow function.
Also, you need to pass unique key to elements when used inside map, you can use index as a key but if you are mutating the array then use some id or hash or anything which will be unique.
class Blog extends React.Component {
state= {
open: {}
}
handleClick = (k) => {
let linkOpenState = false;
if (this.state.open.hasOwnProperty(k)) {
linkOpenState = this.state.open[k];
}
this.setState({ open: { [k]: linkOpenState } })
}
render(){
return(
posts.map((i, index)=>(
<div class="box" key={i.id || index}>
<article class="media">
<div class="media-content">
<div class="content">
<h1 class="title">{i.title}</h1>
<p>
{i.content}
</p>
</div>
<div class="tags">
{i.hash.map(k=>(<span key={k} id={k} onClick={() => this.handleClick(k)} class={this.state.open[k]? "tag is-primary" : "tag"} >{k}</span>))}
</div>
</div>
</article>
</div>))
)
}
}
export default Blog

React Error: Nothing was returned from render. This usually means a return statement is missing. Or, to render nothing, return null

EDIT: [SOLVED by the community - in the answers!] Thanks everyone
I'm trying to add search functionalities to my webApp (a list of the movies I own). To do this, from the app I'm calling a functional component (MovieListFiltered) which has the following code:
MovieListFiltered.js:
import React from 'react'
const MovieListFiltered = (props) => {
const newData = props.moviesAfterFilter
if(newData !== null) {
const newMovies = newData.map((movie, i) =>
{
return(
<div className="col s12 m3 l3" key={i} movieid ={movie.idFromTmdb}>
<div className="card">
<div className="card-image waves-effect waves-block waves-light">
<img src={movie.url2poster} alt={movie.movieTitle} className="responsive-img" />
<p className="littleFont" align="center"><span><b>{movie.movieTitle}</b></span></p>
</div>
<div className="card-action">
<a href="#" onClick={() => this.props.viewMovieInfo(movie.idFromTmdb)}>Movie Details</a>
</div>
</div>
</div>
);
})
console.log(newMovies)
props.movieCallback(newData, newMovies);
} else {
return null
}
}
export default MovieListFiltered
So, basically, notything special there: you see many console.log calls, that was just to make sure the correct array of data was passed (and it is!)
In App.js:
... code not interesting goes here ...
callbackFromList = (childDataData, childDataMovies) => {
this.setState({moviesToFilter: childDataData});
this.setState({moviesToShow: childDataMovies});
this.setState({totalResults: childDataData.length});
}
render()
{
... some not interesting code goes here...
return(
<div className="App">
<Nav />
<div>
<div className="container">
<div className="row">
<div className="col s10 offset-s1">
<MovieListFiltered viewMovieInfo={this.viewMovieInfo} movieCallback={() => this.callbackFromList} ref={this.movieListRef} moviesAfterFilter={this.state.moviesFiltered}></MovieListFiltered>
</div>
</div>
</div>
</div>
</div>
);
}
Can you please help me? I've read all the questions already made here on stackoverflow, but nothing seems to fit to my case.

I think you are wanting something like this:
const MovieListFiltered = (props) => {
const newData = props.moviesAfterFilter
if(newData !== null) {
const newMovies = newData.map((movie, i) => (
<div className="col s12 m3 l3" key={i} movieid ={movie.idFromTmdb}>
<div className="card">
<div className="card-image waves-effect waves-block waves-light">
<img src={movie.url2poster} alt={movie.movieTitle}
className="responsive-img" />
<p className="littleFont" align="center"><span><b>
{movie.movieTitle}</b></span></p>
</div>
<div className="card-action">
<a href="#" onClick={() =>
this.props.viewMovieInfo(movie.idFromTmdb)}>Movie Details</a>
</div>
</div>
</div>
);
)
console.log(newMovies)
props.movieCallback(newData, newMovies)
return newMovies
} else {
return null
}
}

Here a cleaner version with only one return. That may not be what you're looking for though.
import React from 'react'
const MovieListFiltered = (props) => {
const newData = props.moviesAfterFilter || []; // add 'or' if null or undefined
const newMovies = newData.map((movie, i) => (
<div className="col s12 m3 l3" key={i} movieid ={movie.idFromTmdb}>
<div className="card">
<div className="card-image waves-effect waves-block waves-light">
<img src={movie.url2poster} alt={movie.movieTitle} className="responsive-img" />
<p className="littleFont" align="center"><span><b>{movie.movieTitle}</b></span></p>
</div>
<div className="card-action">
<a href="#" onClick={() => this.props.viewMovieInfo(movie.idFromTmdb)}>Movie Details</a>
</div>
</div>
</div>
));
console.log(newMovies)
props.movieCallback(newData, newMovies);
return newMovies;
}
export default MovieListFiltered

You are only returning a value from the else block. The if block is not currently returning anything. You probably want to make the last line of the if block return newMovies;
import React from 'react'
const MovieListFiltered = (props) => {
const newData = props.moviesAfterFilter
if(newData !== null) {
const newMovies = newData.map((movie, i) =>
{
return(
<div className="col s12 m3 l3" key={i} movieid ={movie.idFromTmdb}>
<div className="card">
<div className="card-image waves-effect waves-block waves-light">
<img src={movie.url2poster} alt={movie.movieTitle} className="responsive-img" />
<p className="littleFont" align="center"><span><b>{movie.movieTitle}</b></span></p>
</div>
<div className="card-action">
<a href="#" onClick={() => this.props.viewMovieInfo(movie.idFromTmdb)}>Movie Details</a>
</div>
</div>
</div>
);
});
console.log(newMovies);
props.movieCallback(newData, newMovies);
return newMovies;
}
return null;
}
export default MovieListFiltered
Also, you might notice I got rid of the entire else block - this is because it's not necessary if you return from the corresponding if block.

Using odd/even switch for classNames

I want each this.state.title to align according to a different classname.
I tried using css flex boxes/nth-of-type/nth-child, but it did not play nicely with React.
I'm using this.state to get my objects.
My unsuccessful attempt
render: function () {
let className
var newVar = !someVar;
switch(someVar) {
case odd:
className= "post-1 line";
break;
case even:
className = "post-2 right-align line";
break;
}
return (
<article class={I WANT THIS TO FILL FROM SWITCH}>
<div class="s-12 l-6 post-image">
<a href="post-1.html">
<img src="/post1.jpg">
</a>
</div>
<div class="s-12 l-5 post-text">
<a href="#">
<h2>{this.state.title}</h2>
</a>
<p>Testing
</p>
</div>
<div class="s-12 l-1 post-date">
<p class="date">28</p>
<p class="month">feb</p>
</div>
</article>
);
}
});

react rewrite class attribute as className,see react for more details.
render: function () {
let className = ['post-2 right-align line', 'post-1 line'][someVar % 2];
return (
<article className={className}>
<div className="s-12 l-6 post-image">
<a href="post-1.html">
<img src="/post1.jpg"/>
</a>
</div>
<div className="s-12 l-5 post-text">
<a href="#">
<h2>{this.state.title}</h2>
</a>
<p>Testing
</p>
</div>
<div className="s-12 l-1 post-date">
<p className="date">28</p>
<p className="month">feb</p>
</div>
</article>
);
}

The 'someVar' is local variable ? You can try write it in state, Via this.setState mutate it for your need.

here is the whole example like this:
class Item extends Component {
render() {
let {index, title}=this.props;
let className = ['post-2 right-align line', 'post-1 line'][index % 2];
return <li key={index} id={index} className={className}>{title}</li>
}
}
class TodoList extends Component {
render() {
let i = 0;
let itemFactory = (props = {}) => {
return <Item key={i} index={i++} {...props}/>
};
return (<ul>
{this.props.items.map((item) => itemFactory({title: item}))}
</ul>);
}
}
ReactDOM.render(
<TodoList items={['first', 'second', 'last']}/>,
document.getElementById('container')
);

attach onClick handler to populated list item reactjs

i have a function that i want to fire when a button is being clicked, this button is included in a list item that gets populated based on values from an array passed from the parent component, but its not working and returning an error saying that the function is undefined, how can i make this work?
import React from 'react';
export default class Card extends React.Component {
constructor(){
super()
this.state = {
index: null
};
}
handleClick(x){
this.setState({
index: x
})
}
render(){
/**
* Populates list items according to data passed
* on to resultsArray.
*/
var items = this.props.resultsArray;
var itemslist = items.map(function(item, index){
return(
<li key={ index } class="card" >
<div class="card-header">
<span class="hour-price"><span>{ item.hourPrice } € /hour</span></span>
<img src={ item.image } class="card-img" />
Book
</div>
<div>
<div class="card-info">
<p class="workplace-name">{ item.name }</p>
<span class="score">{ item.score } ★</span>
<p class="location">{ item.location }</p>
</div>
<div class="card-footer">
<p class="price">{ item.price } € / Day</p>
</div>
</div>
</li>
);})
return(
<div class="results-container">
<ul class="card-list center">
{ itemslist }
</ul>
</div>
);
}
}

You should change your render to the below codes. Use that instead of this.
var items = this.props.resultsArray;
var that = this;
var itemslist = items.map(function(item, index){
return(
<li key={ index } className="card" >
<div className="card-header">
<span className="hour-price"><span>{ item.hourPrice } € /hour</span></span>
<img src={ item.image } className="card-img" />
Book
</div>
......

How to show loader in reactjs and meteor?

I have a page where 3 recipes are listed along with more button. When more button is clicked more 3 recipes are listed. What i am trying to do is before listing more 3 recipes i want to show a spinner/loader icon but i could only change the text of button. How can i show loader icon as soon as more button is clicked and before those additional 3 recipes are listed. I am using meteorjs and reactjs.
my code for this is
export default class Home extends Component {
constructor(){
super();
this.state = { limit:3 , loading:false }
this.addMore = this.addMore.bind(this);
}
getMeteorData(){
let data = {};
data.recipes = [];
data.recipes = Recipes.find({},{sort:{createdAt:-1}}).fetch();
let recipeHandle = Meteor.subscribe('recipelist',this.state.limit);
if(recipeHandle.ready()){
data.recipes = Recipes.find({},{sort:{createdAt:-1},limit:this.state.limit}).fetch();
}
return data;
}
addMore(){
this.setState({
limit:this.state.limit + 3, loading: true }, () => {
this.setTimeout(()=>{
this.setState({loading:false});
},2000);
});
}
render() {
console.log('this.data.recipes',this.data.recipes);
let recipes = _.map(this.data.recipes,(recipe) => {
return <RecipeList key={recipe._id} recipe={recipe} loading={this.state.loading} />
});
return (
<div className="row">
<div className="intro blink z-depth-1">
<div className="row">
<div className="col l7">
<h1 className="heading flow-text blink">Sell your Recipe</h1>
</div>
</div>
</div>
<div className="row">
<div className="col s12">
{recipes}
</div>
</div>
<button onClick={this.addMore} type="button" className="btn coral more">More</button>
</div>
);
}
}
ReactMixin(Home.prototype, ReactMeteorData);

You could remove the loading state, and just compute the loading state from the data: {this.state.limit !== this.data.recipes.length && <img src="path_to_loader.gif" />}
I am not sure where you want to show the loader, but for example you could do:
render() {
console.log('this.data.recipes',this.data.recipes);
let recipes = _.map(this.data.recipes,(recipe) => {
return <RecipeList key={recipe._id} recipe={recipe} loading={this.state.loading} />
});
return (
<div className="row">
<div className="intro blink z-depth-1">
<div className="row">
<div className="col l7">
<h1 className="heading flow-text blink">Sell your Recipe</h1>
</div>
</div>
</div>
<div className="row">
<div className="col s12">
{recipes}
</div>
</div>
{this.state.limit !== this.data.recipes.length && <img src="path_to_loader.gif" />}
<button onClick={this.addMore} type="button" className="btn coral more">More</button>
</div>
);
}