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Component Level OnChange Event?

- 1 answer

I have an options page comonent. This component is composed of row. Each row is a setting. That setting is either a select, check, radio, or custom element. This component is updated in two ways:

  1. AJAX tells it to update with setState - this setState I classify not as component onChange but JUST component update
  2. User manipulates a row, triggering the select/radio/check onChange to trigger, the onChange triggers a setState on the top most component - this setState I classify as component onChange

When #2 happens, meaning the user manipulated component, I want the onChange on the top most component to fire. Is there an event like this? I cant seem to find it in component life cycle.

Reason why I cannot use componentDidUpdate, is because when user triggers onChange of row, I need to make a request to server with the new info. If AJAX tells the compoent to update, onComponentDidUpdate will trigger, but I don't need to make an AJAX request.

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Answer

You can do that by passing a callback from Top Component on its Child component Property. The callback then will be invoked by Child component onChange event by using this.props.callbackName(). For example

TopComponent.js

 // import react (i'm using es2015)
 // but the concept is the same whether you use it or not

 import React, {Component} from 'react'

 class TopComponent extends Component {

     // the callback
     onChildComponentChange(){
       doAjax().then(function(data){
         this.setState({foo: data})
       })

     }

     render(){
         return (<ChildComponent onPropertyChange={this.onChildComponentChange}) />
     }
 }

ChildComponent.js

import React, {Component} from 'react'

class ChildComponent extends Component {

  onChangeHandler(){
    // from this handler we call the top component callback
    this.props.onPropertyChange(data) // the name of props we pass from top component
  }
  render(){
    return (<RowComponent onClick={this.onChangeHandler}/>)
  }
}
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source: stackoverflow.com
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