onChange event for React child component to update state

Question

I\'m trying to learn how to implement a React form (ES6 syntax) and pass the onChange events for each field up to a controller parent component which is responsible for upda

Answer 1

import React from 'react'
export default {
  [formData, setFormData] = React.useState({
    name: '',
    number: '',
    email: '',
    address: '',
    zip: ''
  })

  const handleChange = (e) => {
    setFormData({ ...formData, [e.target.name]: e.target.value })
  }
  
  return (
    <div>
      <input type='text' name='name' onChange={handleChange} />
      <input type='text' name='number' onChange={handleChange} />
      <input type='email' name='email' onChange={handleChange} />
      <textarea name='address' onChange={handleChange}></textarea>
      <input type='text' name='zip' onChange={handleChange} />
    </div>
  )
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

Answer 2

The onChange handler for the DatePicker is not called with a standard browser change event, but with value and formattedValue as arguments. I would recommend to register different onChange handlers in your Child component that transform the respective input field's event:

Controller Component

class Parent extends React.Component {
    constructor (props) {
        super(props);
        this.state = {} 
    }

    onChange(field, value) {
        // parent class change handler is always called with field name and value
        this.setState({[field]: value});
    }


    render () {
        return <Child onChange={this.onChange.bind(this)} />
    }
}

Child Component

class Child extends React.Component {
    constructor (props) {
        super(props);
    }

    onFieldChange(event) {
        // for a regular input field, read field name and value from the event
        const fieldName = event.target.name;
        const fieldValue = event.target.value;
        this.props.onChange(fieldName, fieldValue);
    }

    onDateChange(dateValue) {
        // for a date field, the value is passed into the change handler
        this.props.onChange('dateCommenced', dateValue);
    }

    render () {
        return <form>
          <input type="text" name="jobNumber" onChange={this.onFieldChange.bind(this)} /> 
          <DatePicker onChange={this.onDateChange.bind(this)}  />
        </form>
    }
}