Updating state on props change in React Form

React is a popular JavaScript library for building user interfaces. One common scenario in React development is updating the state of a component when its props change. This is especially useful in forms, where we want to keep the form fields in sync with the data passed from a parent component.

In this blog post, we will explore two solutions for updating state on props change in a React form.

Solution 1: Using componentDidUpdate

The componentDidUpdate lifecycle method is called after the component updates, including when props change. We can leverage this method to update the state based on the new props.

{`
  class MyForm extends React.Component {
    constructor(props) {
      super(props);
      this.state = {
        inputValue: ''
      };
    }
    
    componentDidUpdate(prevProps) {
      if (prevProps.formData !== this.props.formData) {
        this.setState({ inputValue: this.props.formData });
      }
    }
    
    handleInputChange = (event) => {
      this.setState({ inputValue: event.target.value });
    }
    
    render() {
      return (
        
          
        
      );
    }
  }
  
  ReactDOM.render(
    ,
    document.getElementById('root')
  );
  `}

In this example, we have a form component called MyForm. The initial state of the component is set with the value passed as the formData prop. When the component updates and the formData prop changes, the componentDidUpdate method is called. We compare the previous props with the current props and update the state accordingly.

Solution 2: Using static getDerivedStateFromProps

Starting from React 16.3, we have another option for updating state based on props changes using the static getDerivedStateFromProps lifecycle method. This method is called before rendering and allows us to update the state based on the new props.

{`
  class MyForm extends React.Component {
    constructor(props) {
      super(props);
      this.state = {
        inputValue: ''
      };
    }
    
    static getDerivedStateFromProps(nextProps, prevState) {
      if (nextProps.formData !== prevState.inputValue) {
        return { inputValue: nextProps.formData };
      }
      return null;
    }
    
    handleInputChange = (event) => {
      this.setState({ inputValue: event.target.value });
    }
    
    render() {
      return (
        
          
        
      );
    }
  }
  
  ReactDOM.render(
    ,
    document.getElementById('root')
  );
  `}

In this example, we use the static getDerivedStateFromProps method to update the state based on the new props. If the formData prop is different from the current inputValue state, we return a new state object to update the inputValue. Otherwise, we return null to indicate no state update is needed.

Both solutions achieve the same result of updating the state on props change in a React form. Choose the one that suits your coding style and project requirements.

That’s it! Now you know how to update state on props change in a React form using two different approaches. Happy coding!

Updating state on props change in React Form