You don't have to read the whole code, just read the comment in the editQuantity function and in showOrderItem function, specially in the showOrderItem function and my problem is i think just silly, as both of my function are working as they supposed to work,
*editQuantity function supposed to change the state, it changing it, i checked by adding the console line.
*showOrderItem function supposed display the item, he is doing that job as well.
My problem is, i try to add conditional rendering in the showOrderItem function that not working, even though i am able to change the state.
Please read the comment in showOrderItem function, to see where is the problem:
import React from 'react';
export default class ShowOrder extends React.Component{
constructor(props){
super(props);
this.state={
quantityEditing:this.props.orderItems,
}
}
editQuantity(item){
const order=this.state.quantityEditing;
for(var i =0; i<order.length; i++){
if(order[i].item==item){
console.log(order[i].orderQuantityEditing)
order[i].orderQuantityEditing=true;
this.setState({order:this.state.quantityEditing})
console.log(order[i].orderQuantityEditing)
}
}
}
showOrderItem(){
const style = {cursor:'pointer'}
const orderItems=this.state.quantityEditing;
console.log(orderItems)
const orderItem=orderItems.map((item,index)=>
<p>
{orderItems.orderQuantityEditing ? 'some':
<span style={style} onClick={this.editQuantity.bind(this,item.item)}>
//as you can see in here i added conditional rendering, that if orderItems.orderQuantityEditing is true display me some, but that's not working --orderItems.orderQuantityEditing ? 'some'(this part) does not matter how many times i click on property it never display me my string 'some'
{item.quantity}</span>}
<span style={style}> {item.item}</span>
<span style={style}> Q</span>
<span style={style}> N</span>
<span style={style}> X</span>
</p>
);
return orderItem;
}
render(){
return(
<div>
{this.showOrderItem()}
</div>
);
}
}
Instead of
{orderItems.orderQuantityEditing ?
'some'
:
<span style={style} onClick{this.editQuantity.bind(this,item.item)}>
I think you need to write this:
{item.orderQuantityEditing ?
'some'
:
<span style={style} onClick={this.editQuantity.bind(this,item.item)}>
Because you are using map, and item will be each object of array, so you need to use item to access that property. During the for loop, when changing the state you wrote:
order[i].orderQuantityEditing=true;
That it proper, order will be an array and you need to provide the index to access particular object of that.
Related
class Headers extends React.Component {
render() {
const selected = this.props.selectedPane;
const headers = this.props.panes.map((pane, index) => {
const title = pane.title;
const klass = index === selected ? 'active' : '';
return (
<li
key={index}
className={klass}
onClick={() => this.props.onTabChosen(index)}>
{title}{' '}
</li>
);
});
return (
<ul className='tab-header'>
{headers}
</ul>
);
}
}
export default class Tabs extends React.Component {
constructor(props) {
super(props);
this.state = {
selectedPane: 0
};
this.selectTab = this.selectTab.bind(this);
}
selectTab(num) {
this.setState({selectedPane: num});
}
render() {
const pane = this.props.panes[this.state.selectedPane];
return (
<div>
<h1>Tabs</h1>
<div className='tabs'>
<Headers
selectedPane={this.state.selectedPane}
//onTabChosen={this.selectTab}
panes={this.props.panes}>
</Headers>
<div className='tab-content'>
<article>
hellooooo
{pane.content}
</article>
</div>
</div>
</div>
);
}
}
I'm currently creating a 3 tab section where if you click on a tab, it gives you a new pane.
When looking at the render function I see a custom tag called Headers.
I know it coming from the Headers class at the beginning, but how does that format work? Is that a custom tag we building?
Also when looking at its properties such as onTabChosen, when it is deleted in the render method (for learning purposes) and I click on a selected tab, an error comes up saying
"_this.props.onTabChosen is not a function".
this.props.onTabChosen(index).. was written in the Headers class but not as a function correct?
I guess because I am also confused on how this.props.onTabChosen(index) works since onTabChosen was never declared anywhere, just input after props.
When looking at the render function I see a custom tag called "Headers".
That is not a custom tag. That is a React Component.
I know it coming from the Headers class at the beginning, but how does that format work?
Headers is either a function or a class (i.e. a constructor function).
The function will be called and the first argument passed to it will be an object with properties and values that match the props on the JSX element.
If you're going to use React then read a tutorial, this is very introductory level stuff for the framework.
It is covered very early on in both the MDN tutorial and the official React tutorial.
I guess because I am also confused on how this.props.onTabChosen(index) works since onTabChosen was never declared anywhere, just input after props.
It was declared, just not in the piece of code you shared.
I have tried finding the answer to this on StackOverflow and there are some related posts (e.g. React Child Component Not Updating After Parent State Change) but I want to understand why this is not working...
I have a React application that will display a layout of character cards (that is, each card displays a different character). It uses a child component, CharacterBoard, that lays out the CharacterCards, which would be a grandchild component. I pass the characters down from the App to the CharacterBoard as props, and CharacterBoard in turn maps these out the CharacterCards.
The problem is that I want the state of the character to change when I click on one of them. Specifically, I want the revealed field to change. However, even though the state change is reflected in the array of characters in the App (that is, the revealed field changes correctly), and the change is reflected in the array of characters in CharacterBoard, but not in CharacterCard. In fact, my mapping does not seem to be called at all in CharacterBoard when the props change.
Do I need to use something like getDerivedStateFromProps in CharacterBoard and set the state of that component and then use the state to map the values down to CharacterCard? If so, why?
In short (tl;dr), can you pass props on down through the component chain and map them out along the way and still have all changes reflected automatically?
Thanks for any guidance.
If it helps, the render method of my App is
render() {
const {state: {characters}} = this
return (
<div>
<header>
</header>
<main>
<CharacterBoard
onCardSelected={this.onCardSelected}
rowSize={logic.ROW_SIZE}
characters={characters}
cardSize={this.CARD_SIZE}/>
</main>
</div>
);
}
that of CharacterBoard is
render() {
const {props: {characters, rowSize, cardSize,onCardSelected}} = this
const rowUnit = 12 / rowSize
const cardLayout = characters
.map((character, i) => (
<Col xs={6} sm={rowUnit} key={character.name}>
<CharacterCard
onCardSelected = {onCardSelected}
key={i + Math.random()}
character={character}
cardSize={cardSize}
/>
</Col>
)
)
return (
<div>
<Container>
<Row>
{cardLayout}
</Row>
</Container>
</div>
)
}
and finally CharacterCard has this render method
render() {
const {props: {character, cardSize}} = this
const {thumbnail, revealed} = character
const imgURL = `${thumbnail.path}/${cardSize}.${thumbnail.extension}`
const topCardClass = classNames('characterCard__card-back', {'characterCard__card-back--hidden': revealed})
console.log(revealed)
return < a href="/#" onClick={this.onCardSelected}>
<div className='characterCard__card'>
<div className={topCardClass}>
<img src="/images/card_back.png" alt=""/>
</div>
< div className='characterCard__card-front'>< img alt=''
src={imgURL}/>
</div>
</div>
</a>
}
Doh! A simple forgetting to setState in App. Knowing that it should work made me go back through the code one more time and see that, indeed, it was a stupid error on my part.
I am starting my adventure with React so it is a hard time for me, however I prepared such pen for you to test. Here is a portion of code:
class App extends React.Component {
constructor() {
super();
this.state = {
settings: true,
next: false,
};
}
toggler(abc) {
console.log(">>", abc)
this.setState({
next: !this.state.next
/* {abc}: this.state.{abc} */
})
console.log(this.state.next)
}
render() {
return (
<div className="kalreg">
<MyButton name='settings' isActive={this.state.settings} type="settings" toggle={this.toggler.bind(this)}/>
<MyButton name='settings2' isActive={this.state.settings} type="settings" toggle={this.toggler.bind(this)}/>
<MyButton name='next' isActive={this.state.next} type="next" toggle={this.toggler.bind(this)}/>
</div>)
}
}
class MyButton extends React.Component {
constructor(props) {
super(props);
}
onChangeName(){
console.log(this.props.type)
if ( this.props.isActive ) { console.log("this one is active"); } else { console.log("ouch! it is not active, ignoring!"); return;}
this.props.toggle(this.props.type);
}
render () {
if ( this.props.isActive ) {
return ( <div className="button notVisible" onClick={this.onChangeName.bind(this)}>{this.props.name}</div>)
} else {
return ( <div className="button visible" onClick={this.onChangeName.bind(this)}>{this.props.name}</div>)
}
}
}
ReactDOM.render(<App />, document.getElementById("app"));
What I am trying to achieve is that when i press one of "settings" buttons (yellow) the "next" button becomes unclickable (green). There is a toggle function that every time I click settings button it turns on and off "next" button.
It works quite good, however it is just a draft of bigger project and i want to automate it a little bit.
As you can see I create my <MyButton> with both "isActive" and "type" props. But isActive holds what's inside this.state.settings while type is "settings". Instead of using two variables it would be great to pass only type of button to its component and component, depending on its type would check its parent's this.state.{type}. I used {type} because i would like to check it dynamically. Is that possible?
If so - how to do it?
My first attempt is to pass type from <MyButton> to <App> via toggler function. I named the variable "abc". I commented the way I wanted to do it because it doesn't work:
{abc}: !this.state.{abc}
Any idea to solve this problem would be more than appreciated.
Kalreg.
It is somewhat unclear what you are trying to achieve here. If you want to wire the state dynamically based on type, as you wrote in code: {abc}: !this.state.{abc} each button would toggle itself, not the next button. In this case your syntax is a little incorrect, it will work if you write it like:
[abc]: !this.state[abc]
However as I said, in your example, this makes the settings button change the state for this.state.settings disabling itself instead of the next button.
Another note would be, that if it is not necessary for the MyButton component to know its own type for other reasons, it is unnecessary to pass it as a prop and than make the component pass it back as an argument (this.props.toggle(this.props.type);). You can simply define the toggle function in the parent as:
toggle={() => this.toggler("settings")}
without passing type as a prop.
So basically we want to have the settings and settings2 buttons, and when we click on them, they toggle the state of the next button by making it un-clickable (green).
So if that is our goal, then
we don't need an isActive prop for the settings button. (Because it's always going to be active no matter what)
We also don't need to have a toggle prop on the Next button. (Because clicking the next button isn't supposed to toggle anything)
Instead of having two variables in the state why not just have one and then use that to determine the isActive prop of the next button?
The component would look like this:
constructor() {
super();
this.state = {
nextIsActive: false,
};
}
toggler() {
this.setState({
nextIsActive: !this.state.nextIsActive
})
console.log(this.state);
}
render() {
const {nextIsActive} = this.state
return (
<div className="kalreg">
<MyButton name='settings' isActive={true} type="settings" toggle={this.toggler.bind(this)}/>
<MyButton name='settings2' isActive={true} type="settings" toggle={this.toggler.bind(this)}/>
<MyButton name='next' isActive={nextIsActive}/>
</div>
)
}
That way you don't have to have 2 state properties that you have to dynamically update because it adds more complexity to your application.
You can see the finished product here: Codepen
I'm new to react and have to make a project for my bootcamp with it and I am having trouble getting every movie component I render to have an individual button. Every time I click one button, the rest of the buttons on the page act like they are also clicked. Here is my movie component that is being called on.
Heres my first row of components and the buttons are the green ones on the bottom left corner. https://files.slack.com/files-pri/T571CRHGE-F826BKX7S/api.png.
importReact, { Component} from"react";
importAPIfrom"../utils/API"
classMovieextendsComponent{
constructor(){
super();
this.state={
color:'green',
icon:'add',
result:[]
};
}
componentDidMount() {
this.topMovies();
}
topMovies=() =>{
API.topMovies()
.then(res=>this.setState({ result:res.data.results}))
.catch(err=>console.log(err));
}
handleClick=event=>{
if(this.state.color==='green'){
this.setState({color:'red'});
} else{
this.setState({color:'green'});
}
if(this.state.icon==='add') {
this.setState({icon:'remove'});
} else{
this.setState({icon:'add'});
}
}
render() {
constimgURL="https://image.tmdb.org/t/p/w300/"
return(
<div>
{
this.state.result.map((movieList) =>(
<div className="col s4 movieBox">
<div className="card">
<div className="card-image">
<img src={imgURL +movieList.poster_path} />
<span className="card-title"><a id={this.state.color} onClick={this.handleClick} className="btn-floating btn waves-effect waves-light"><i className="material-icons">{this.state.icon}</i></a></span>
</div>
<div className="card-content movieInfo">
<p>Title:{movieList.title}</p>
<p>Genre:{movieList.genre_ids}</p>
<p>Rating:{movieList.vote_average}</p>
</div>
</div>
</div>
))
}
</div>
)
}
}
exportdefaultMovie;
You need to bind the handleClick function ( in fact all functions ) inside the constructor:
constructor(){
super();
this.state={
color:'green',
icon:'add',
result:[]
};
this.handleClick = this.handleClick.bind(this);
}
onClick={()=> this.handleClick()} will also work.
.map() calls a provided callback for each element in your array. So this means that you are creating several buttons that will execute the same event on each of your elements. I suggest creating a row component that handles your onClickEvent and then you could pass the component an id or use an in line arrow function () => this.handleClick(). (this does create a anonymous function on each click and could potentially be bad for performance in larger apps but could work in your case if you don't want to create a row component)
Also you should read up on why using keys with unique ids is important.
https://coderwall.com/p/jdybeq/the-importance-of-component-keys-in-react-js
Hope that helps.
I need to have 2 sibling components, and 1 of them has to have a reference to another - is that possible?
I tried this:
<button ref="btn">ok</button>
<PopupComponent triggerButton={this.refs.btn} />
And even this
<button ref="btn">ok</button>
<PopupComponent getTriggerButton={() => this.refs.btn} />
But I get undefined in both situations. Any ideas?
Note: a parent component will not work for me, because I need to have multiple sets of those, like
<button />
<PopupComponent />
<button />
<PopupComponent />
<button />
<PopupComponent />
NOT like this:
<div>
<button />
<PopupComponent />
</div>
<div>
<button />
<PopupComponent />
</div>
<div>
<button />
<PopupComponent />
</div>
Think this question is best answered by the docs:
If you have not programmed several apps with React, your first
inclination is usually going to be to try to use refs to "make things
happen" in your app. If this is the case, take a moment and think more
critically about where state should be owned in the component
hierarchy. Often, it becomes clear that the proper place to "own" that
state is at a higher level in the hierarchy. Placing the state there
often eliminates any desire to use refs to "make things happen" –
instead, the data flow will usually accomplish your goal.
Not sure exactly what you are trying to do, but my hunch is a parent component and passing props is what you really want here.
I completely agree with the quote Mark McKelvy has provided. What you are trying to achieve is considered an anti-pattern in React.
I'll add that creating a parent component doesn't necessarily means it has to be a direct parent, you can create a parent component further up the chain, in which you can render an array of all your children components together, having the logic to coordinate between all the children (or pairs of children according to your example) sit inside your parent.
I created a rough example of the concept which should do the trick:
class A extends React.Component {
onClick(key) {
alert(this.refs[key].refs.main.innerText);
}
render() {
var children = [];
for (var i = 0; i < 5; i++)
children.push.apply(children, this.renderPair(i));
return (
<div>
{children}
</div>
);
}
renderPair(key) {
return [
<B ref={'B' + key} key={'B' + key} onClick={this.onClick.bind(this, 'C' + key)}/>,
<C ref={'C' + key} key={'C' + key} onClick={this.onClick.bind(this, 'B' + key)}/>
];
}
}
class B extends React.Component {
render() {
return <p ref="main" onClick={this.props.onClick}>B</p>;
}
}
class C extends React.Component {
render() {
return <p ref="main" onClick={this.props.onClick}>C</p>;
}
}
React.render(<A/>, document.getElementById('container'));
And any state you need to save for all your children, you do in the common parent. I really hope this helps.
The following code helps me to setup communication between two siblings. The setup is done in their parent during render() and componentDidMount() calls. Hope it helps.
class App extends React.Component<IAppProps, IAppState> {
private _navigationPanel: NavigationPanel;
private _mapPanel: MapPanel;
constructor() {
super();
this.state = {};
}
// `componentDidMount()` is called by ReactJS after `render()`
componentDidMount() {
// Pass _mapPanel to _navigationPanel
// It will allow _navigationPanel to call _mapPanel directly
this._navigationPanel.setMapPanel(this._mapPanel);
}
render() {
return (
<div id="appDiv" style={divStyle}>
// `ref=` helps to get reference to a child during rendering
<NavigationPanel ref={(child) => { this._navigationPanel = child; }} />
<MapPanel ref={(child) => { this._mapPanel = child; }} />
</div>
);
}
}
special-props
Special Props Warning
Most props on a JSX element are passed on to the component, however, there are two special props (ref and key) which are used by React, and are thus not forwarded to the component.
For instance, attempting to access this.props.key from a component (eg. the render function) is not defined. If you need to access the same value within the child component, you should pass it as a different prop (ex: ). While this may seem redundant, it's important to separate app logic from reconciling hints.