在ReactJS中从子级访问父类方法

Question

I have a small problem where I have parent class and child class. I want to modify the state that was initialized in parent class so that I can see updated state in parent class. Here's the code:

var Parent = React.createClass({
    getInitialState: function(){
        return{
           my_value: 0
        }
    },

    _increaseValue: function(){
        this.state.my_value++;
    },

    render: function(){
        return(
            <div><Child /></div>
        )
    }
});

var Child = React.createClass({
    render: function(){
        //at button I want to access _increaseValue function of parent
        return (
            <div>
                 <button onClick={_increaseValue}>Increase</button>
            </div>
        );
    }
});

Now when user clicks the button in child class I would like to get the updated my_value in parent class, thus my questions are:

1. Is it possible?
2. If yes, how it is done?
3. Is this good practice or no?

Answer 1

1. Is it possible?

   yes, it is possible

2. If yes, how it is done?

   you can pass parent method to child through props , like so

    var Parent = React.createClass({ getInitialState: function(){ return { my_value: 0 } }, onChangeValue: function () { var value = this.state.my_value + 1; this.setState({ my_value: value }) }, render: function() { return <div> <Child onChangeValue={ this.onChangeValue } value={ this.state.my_value } /> </div>; } }); var Child = React.createClass({ _handleClick: function(){ this.props.onChangeValue(); }, render: function(){ return <div> <h1> { this.props.value } </h1> <button onClick={ this._handleClick }>Increase</button> </div> } }); 

   Example

3. Is this good practice or no?

   It is good practice

Answer 2

You need to pass function via props into your child component. And when you need to change you call this function. It is normal practice and react way.

Example:

var Parent = React.createClass({
    getInitialState: function(){
        return{
           my_value: 0
        }
    },

    onChildClick: function() {
        this.setState({
          my_value: this.state.my_value + 1
        })
    },

    render: function(){
        return(
            <div>
              {this.state.my_value}
              <Child onClick={this.onChildClick.bind(this)}/>
            </div>
        )
    }
});

var Child = React.createClass({
    _handleClick: function(){
        this.props.onClick();
    },

    render: function(){
        return (
            <div>
                 <button onClick={this._handleClick}>Increase</button>
            </div>
        );
    }
});

Example on JSFiddle