How to assign a prop value to a state in react

问题:

I have an overlay which is launched from another React component which have a button that also changes itself. The change happens when the user clicks the button, then the button changes it's classname. It also sends a prop value to the children component which is the overlay. The overlay adds a class depending on the property and if it is clicked. Everthing is working pretty nice, but now I have to do another thing. When a user click on the overlay, it have to close up. Before this change, everything was working for the button I mentioned earlier.

Well this is the button component:

export default class StatusBarButton extends React.Component {

    constructor(props) {
        super(props)
        this.state = {active: false}
        this.handleClick = this.handleClick.bind(this)
    }

    handleClick() {
        this.setState({ active: !this.state.active });
    }

    render() {
        var cx = require('classnames');
        var button = cx ({
            'statusbar-button-container' : true,
            'active' : this.state.active
        });
        var animation = cx ({
            'statusbar-button-cross-image' : true,
            'rotate' : true,
            'active' : this.state.active
        });

        return (
            <div className="astatusbar-center-wrapper">
                <div className={button} onClick={this.handleClick}>
                    <img src="images/navbar-element-icon-cross.png" className={animation}/>
                </div>      
                <OverlayView isOpen={this.state.active} />
            </div>
        );
    }
}

And this is the Overlay at the moment:

export default class OverlayView extends React.Component {
    constructor (props){
        super(props);
        this.state = {open: false}
        this.setState({ open: this.props.isOpen });
    }



    render() {
        var cx = require('classnames');
        var overlay = cx({
            'overlay': true,
            'overlay-slidedown': true,
            'open': this.state.open
        });

        return (    
            <div className={overlay} onClick={this._closeOverlay}>
                <div className="overlay-menu-wrapper">
                    <OverlayNewInvoiceButton />
                    <OverlayNewBudgetButton />
                    <OverlayNewTicketButton />
                </div>
            </div>
        );
    }
}

As you see I'm trying to get the prop value and assign it to the state, but it's not working. How can I assign the prop value to the state and use it?

Regards, JP

回答1:

You are missing componentWillReceiveProps(props) method in your OverlayView component.

export default class OverlayView extends React.Component {
    constructor (props){
        super(props);
        this.state = {open: props.isOpen}
    }

    componentWillReceiveProps(props) {
        this.setState({open: props.isOpen});
    }

    render() {
        let open = '';
        if (this.state.open === true) {
            open = 'open';
        }

        let overlayClass = `overlay overlay-slidedown ${open}`;

        return (    
            <div className={overlayClass} onClick={this._closeOverlay}>
                <div className="overlay-menu-wrapper">
                    <span>{open}</span>
                </div>
            </div>
       );
    }
}

Full working example: https://codesandbox.io/s/35wLR4nA

回答2:

constructor(props, context) {
    super(props, context);
     this.state = {
           value: ''
      };
   }

   componentWillReceiveProps(){ //this is called to before render method
    this.setState({
       value:this.props.data
     })

回答3:

You're problem might be that you are trying to fetch the class props with this. I think you are supposed to use the props passed into the constructor.

Like this:

constructor (props){
    super(props);
    this.state = {open: false}
    this.setState({ open: props.isOpen });
}

Not sure why you aren't doing it in one line like this though: this.setState = { open: props.isOpen };

回答4:

Finally i conserved the property which changes the class, is not bad that way. and i fixed with the help of this: Pass props to parent component in React.js and of course the help of a work mate. the end version is this:

This is the parent:

export default class StatusBarButtonView_Profit extends React.Component {

    constructor(props) {
        super(props)
        this.state = {active: false}
        this._openOverlay = this._openOverlay.bind(this)
        this._closeOverlay = this._closeOverlay.bind(this)
    }

    _openOverlay() {
        if (this.state.active == false) {
            this.setState({ active: true });
            console.log('boton lanza overlay');
        } else {
            this.setState({ active: false });
            console.log('boton cierra overlay');
        }
    }

    _closeOverlay(Overlay) {
        if (this.state.active == true) {
            this.setState({ active: false });

        } else {
            this.setState({ active: true });
        }
    }

    render() {
        var cx = require('classnames');
        var button = cx ({
            'aui-profit-statusbar-button-container' : true,
            'active' : this.state.active
        });
        var animation = cx ({
            'aui-profit-statusbar-button-cross-image' : true,
            'rotate' : true,
            'active' : this.state.active
        });

        return (
            <div className="aui-profif-statusbar-center-wrapper">
                <div className={button} onClick={this._openOverlay}>
                    <img src="images/aui-navbar-element-icon-cross.png" className={animation}/>
                </div>      
                <OverlayView_Profit isOpen={this.state.active} onClick={this._closeOverlay}/>
            </div>
        );
    }
}

this is the child:

export default class OverlayView_Profit extends React.Component {
    constructor (props){
        super(props);

    }

    _closeOverlay() {
        this.props.onClick();
    }

    render() {
        var cx = require('classnames');
        var overlay = cx({
            'aui-overlay': true,
            'aui-overlay-slidedown': true,
            'open': this.props.isOpen
        });

        return (    
            <div className={overlay} onClick={this._closeOverlay.bind(this)}>
                <OverlayNewInvoiceButtonView_Profit />
                <OverlayNewBudgetButtonView_Profit />
                <OverlayNewTicketButtonView_Profit />
            </div>
        );
    }
}

now everything works fine.