React: Element is changing a controlled input of type text to be uncontrolled

Question

I'm getting the following error but haven't been able to identify why it is happening

warning.js:36 Warning: Searchbox is changing a controlled input of type text to be uncontrolled. Input elements should not switch from controlled to uncontrolled (or vice versa). Decide between using a controlled or uncontrolled input element for the lifetime of the component

I've got the following files:

1. Searchbox.js

import React, { Component } from 'react';
    
    class Searchbox extends Component {
    
      // render method
      render() {
        const { value, onChange, onSubmit, children } = this.props
        console.log(value)
        console.log(onChange)
        console.log(onSubmit)
        console.log(children)
        return (
          <section className="search-section">
            <form onSubmit={onSubmit}>
              <input
                type="text"
                className="search-box"
                value={value}
                onChange={onChange}
              />
              <button type="submit">{children}</button>
            </form>
          </section>
        )
      }
    }
    
    export default Searchbox

And the App.js file

import React, { Component } from 'react';
import Searchbox from './components/Searchbox'
//import logo from './logo.svg';
import './App.css';

const DEFAULT_TERM = 'High Fidelity'

class App extends Component {

  // Constructor
  constructor(props) {
    super(props)

    this.state = {
      movie: null,
      searchTerm: DEFAULT_TERM
    }

    this.onSearchSubmit = this.onSearchSubmit.bind(this)
    this.onSearchChange = this.onSearchChange.bind(this)
  }


  // onSearchSubmit method
  onSearchSubmit(e) {
    e.preventDefault()
    console.log("Searching movie with name" + this.status.searchTerm)
  }

  onSearchChange(e){
    console.log(event.target.value)
    this.setState({ searchTerm: event.target.value })
  }

  // render method
  render() {

    const { movie, searchTerm } = this.state

    return (
      <div className="App">
        <Searchbox
          value={searchTerm}
          onChange={this.onSearchChange}
          onSubmit={this.onSearchSubmit}
        >Search
        </Searchbox>
      </div>
    );
  }
}

export default App;

On load everything's fine, but when I type something in the text field then the error is triggered.

Any suggestions?

Answer 1

The problem is in the onSearchChange function. You have named input's onChange event as e but you are taking value from global variable event

Replace onSearchChange to code mentioned below:

onSearchChange(event) {
   this.setState({ searchTerm: event.target.value })
}

Answer 2

I was receiving the same exact warning. My TextFieldItem is a child component that is being updated through its props. The following line was the culprit.

const fieldValue = (field.Value == null) ? undefined : field.Value;

upon changing the line to set the value from undefined to '' resolved warning.

const fieldValue = (field.Value == null) ? '' : field.Value;

React component

class TextFieldItem extends React.Component{
        constructor(props){
            super(props);
            this.onChange=this.onChange.bind(this);
        }
        onChange(e){
            event.preventDefault();
            const {onFieldChange,field} = this.props;   
            onFieldChange(e.target.id, e.target.value, e.target.name,field.Type);
        }
        render(){        
            const {field, onFieldChange, onRecordUpdate, IsLookupField,record,currentDocumentType} = this.props;       
            const fieldValue = (field.Value == null) ? '' : field.Value;
            return (
                <div>
                    <label>{field.Name}</label> 
                    <input type="text" key={field.Id} className="form-control" id={field.Id} name={field.Name} onChange={this.onChange} value={fieldValue} />     
                    {IsLookupField && <LookupFieldItem record={record} field={field} onRecordUpdate={onRecordUpdate} documentType={currentDocumentType} /> }
                </div>
                );
        }
    }
         export default TextFieldItem;