A component is changing an uncontrolled input of type text to be controlled error in ReactJS

Question

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

Following is my code:

constructor(props) {
  super(props);
  this.state = {
    fields: {},
    errors: {}
  }
  this.onSubmit = this.onSubmit.bind(this);
}

....

onChange(field, e){
  let fields = this.state.fields;
  fields[field] = e.target.value;
  this.setState({fields});
}

....

render() {
  return(
    <div className="form-group">
      <input
        value={this.state.fields["name"]}
        onChange={this.onChange.bind(this, "name")}
        className="form-control"
        type="text"
        refs="name"
        placeholder="Name *"
      />
      <span style={{color: "red"}}>{this.state.errors["name"]}</span>
    </div>
  )
}

Answer 1

The Best Way to Fix This: Set the Initial State to an Empty String ('') ✨

When creating form inputs in React, it’s important to properly initialize the state. If you leave state properties undefined, React may throw warnings like "uncontrolled input," which can clutter your console with big red error blocks. 🚨 To avoid this issue, simply initialize your state with empty strings (''), and everything will work smoothly! Let's walk through examples for class components and functional components. ⬇️

---

Class Component Example 🏛️

Here's how you can fix the problem using a class component:

constructor(props) {
  super(props);
  this.state = {
    fields: {
      first_name: '' // ✅ Start with an empty string!
    }
  };
  this.onChange = this.onChange.bind(this); // Bind the method
}

onChange(e) {
  this.setState({
    fields: {
      ...this.state.fields, // Spread operator to keep other fields
      [e.target.name]: e.target.value // Dynamically update based on the input's name
    }
  });
}

render() {
  return (
    <div className="form-group">
      <input
        value={this.state.fields.first_name} // 🎯 Controlled value
        onChange={this.onChange}
        className="form-control"
        name="first_name" // Matches the state key
        type="text"
        refs="name"
        placeholder="Name *"
      />
      {/* Show validation errors if any */}
      <span style={{ color: "red" }}>{this.state.errors?.first_name}</span>
    </div>
  );
}

---

Functional Component Example ⚛️

Modern React makes it simpler with hooks! Here's how you can achieve the same result using a functional component and the useState hook:

import React, { useState } from 'react';

const InputForm = () => {
  const [fields, setFields] = useState({
    first_name: '' // ✅ Start with an empty string!
  });
  const [errors, setErrors] = useState({}); // Optional: manage validation errors

  const handleChange = (e) => {
    setFields({
      ...fields, // Use the spread operator to keep other fields intact
      [e.target.name]: e.target.value // Dynamically update the input value
    });
  };

  return (
    <div className="form-group">
      <input
        value={fields.first_name} // 🎯 Controlled value
        onChange={handleChange}
        className="form-control"
        name="first_name" // Matches the `fields` key
        type="text"
        placeholder="Name *"
      />
      {/* Display validation errors, if any */}
      <span style={{ color: 'red' }}>{errors?.first_name}</span>
    </div>
  );
};

export default InputForm;

---

Why This Works 🌟

💡 Key Points:

1. Set Default Values: By initializing first_name to '', the input’s value will always be a string, not undefined. This avoids warnings about "uncontrolled inputs." 🚀

2. Dynamic Updates: Both class and functional components use a method (either onChange or handleChange) to update the state as the user types into the input. 🔄

3. Avoid Errors: If you initialize the state with '', you can safely perform checks like if (field) or validations—even if the field is empty—without errors. ✅

4. Clean Console Logs: No more big red error blocks in the console! 🎉 Your console is now clean and happy. 😎

---

In Short:

By initializing the state with an empty string (''), you’re making the value a string by default, instead of letting it stay undefined. This avoids any errors and makes your code safer and easier to debug. Happy hacking! ✌️

Answer 2

The problem occurs even if you set undefined to the value at a previous rendering that happened even before initializing things properly.

The issue went by replacing

value={value}

with

value={(value==undefined?null:value)}

Answer 3

Inside the component put the input box in the following way.

<input
    className="class-name"
    type= "text"
    id="id-123"
    value={ this.state.value || "" }
    name="field-name"
    placeholder="Enter Name"
/>

Answer 4

Change value to defaultValue and it will resolve the error in react or in any other framework.

           <input
            // value={mainOrder.property1}
            defaultValue = {mainOrder.property1}
            onChange={(e) =>
              setMainOrder({ ...mainOrder, property1: e.target.value })
            }
          />

Answer 5

For me, this was the mistake:

<input onChange={onClickUpdateAnswer} value={answer.text}>
  {answer.text}
</input>

As you see, I have passes string into the body of the Input tag,

Fix:

<input onChange={onClickUpdateAnswer} value={answer.text}></input>

Answer 6

I am new to reactjs and I am using version 17 of reactjs I was getting this problem

I solved:

Instead of this

const [email, setEmail] = useState();

I added this

const [email, setEmail] = useState("");

In useState function I added quotes to initialize the data and the error was gone.

Answer 7

that's happen because the value can not be undefined or null to resolve you can do it like this

value={ this.state.value ?? "" }

Answer 8

While this might sound crazy, the thing that fixed this issue for me was to add an extra div. A portion of the code as an example:

  ... [Other code] ...
  const [brokerLink, setBrokerLink] = useState('');
  ... [Other code] ...

  return (
    ... [Other code] ...
              <div styleName="advanced-form" style={{ margin: '0 auto', }}>
                {/* NOTE: This div */}
                <div>
                  <div styleName="form-field">
                    <div>Broker Link</div>
                    <input
                      type="text"
                      name="brokerLink"
                      value={brokerLink}
                      placeholder=""
                      onChange={e => setBrokerLink(e.target.value)}
                    />
                  </div>
                </div>
              </div>
    ... [Other code] ...
  );
... [Other code] ...

Was very strange. Without this extra div, it seems react initially rendered the input element with no value attribute but with an empty style attribute for some reason. You could see that by looking at the html. And this led to the console warning..

What was even weirder was that adding a default value that is not an empty string or doing something like value={brokerLink || ''} would result in the exact same problem..

Another weird thing was I had 30 other elements that were almost exactly the same but did not cause this problem. Only difference was this brokerLink one did not have that outer div.. And moving it to other parts of the code without changing anything removed the warning for some reason..

Probably close to impossible to replicate without my exact code. If this is not a bug in react or something, I don't know what is.

Answer 9

For functional component:

const SignIn = () => {

  const [formData, setFormData] = useState({
    email: "",
    password: ""
  });

  
  const handleChange = (event) => {
    const { value, name } = event.target;
    setFormData({...formData, [name]: value });
  };


  const handleSubmit = (e) => {
    e.preventDefault();
    console.log("Signed in");
    setFormData({
      email: "",
      password: ""
    });
  };


  return (
    <div className="sign-in-container">
      <form onSubmit={handleSubmit}>
        <FormInput
          name="email"
          type="email"
          value={formData.email}
          handleChange={handleChange}
          label="email"
          required
        />
        <FormInput
          name="password"
          type="password"
          value={formData.password}
          handleChange={handleChange}
          label="password"
          required
        />
        <CustomButton type="submit">Sign in</CustomButton>
      </form>
    </div>
  );
};

export default SignIn;

Answer 10

I also faced the same issue. The solution in my case was I missed adding 'name' attribute to the element.

<div className="col-12">
   <label htmlFor="username" className="form-label">Username</label>
        <div className="input-group has-validation">
             <span className="input-group-text">@</span>
                  <input 
                      type="text" 
                      className="form-control" 
                      id="username"
                      placeholder="Username" 
                      required=""
                      value={values.username}
                      onChange={handleChange}
                  />
                  <div className="invalid-feedback">
                      Your username is required.
                  </div>
        </div>
</div>

After I introduced name = username in the input list of attributes it worked fine.

Answer 11

If you're setting the value attribute to an object's property and want to be sure the property is not undefined, then you can combine the nullish coalescing operator ?? with an optional chaining operator ?. as follows:

<input
  value={myObject?.property ?? ''}
/>

Answer 12

As mentioned above you need to set the initial state, in my case I forgot to add ' ' quotes inside setSate();

  const AddUser = (props) => {
  const [enteredUsername, setEnteredUsername] = useState()
  const [enteredAge, setEnteredAge] = useState()

Gives the following error

Correct code is to simply set the initial state to an empty string ' '

  const AddUser = (props) => {
  const [enteredUsername, setEnteredUsername] = useState('')
  const [enteredAge, setEnteredAge] = useState('')

Answer 13

I came across the same warning using react hooks, Although I had already initialized the initial state before as:-

const [post,setPost] = useState({title:"",body:""})

But later I was overriding a part of the predefined state object on the onChange event handler,

 const onChange=(e)=>{
        setPost({[e.target.name]:e.target.value})
    }

Solution I solved this by coping first the whole object of the previous state(by using spread operators) then editing on top of it,

 const onChange=(e)=>{
        setPost({...post,[e.target.name]:e.target.value})
    }

Answer 14

like this

value={this.state.fields && this.state.fields["name"] || ''}

work for me.

But I set initial state like this:

this.state = {
  fields: [],
}

Answer 15

Change this

  const [values, setValues] = useState({intialStateValues});

for this

  const [values, setValues] = useState(intialStateValues);

Answer 16

The reason of this problem when input field value is undefined then throw the warning from react. If you create one changeHandler for multiple input field and you want to change state with changeHandler then you need to assign previous value using by spread operator. As like my code here.

constructor(props){
    super(props)
    this.state = {
        user:{
            email:'',
            password:''
        }
    }
}

// This handler work for every input field
changeHandler = event=>{
    // Dynamically Update State when change input value
    this.setState({
        user:{
            ...this.state.user,
            [event.target.name]:event.target.value
        }
    })
}

submitHandler = event=>{
    event.preventDefault()

    // Your Code Here...
}

render(){
    return (
        <div className="mt-5">
       
            <form onSubmit={this.submitHandler}>
                <input type="text" value={this.state.user.email} name="email" onChage={this.changeHandler} />
                
                <input type="password" value={this.state.user.password} name="password" onChage={this.changeHandler} />

                <button type="submit">Login</button>
            </form>
      

        </div>
    )
}

Answer 17

Put empty value if the value does not exist or null.

value={ this.state.value || "" }

Answer 18

Multiple Approch can be applied:

• Class Based Approch: use local state and define existing field with default value:

constructor(props) {
    super(props);
    this.state = {
      value:''
    }
  }
<input type='text'
                  name='firstName'
                  value={this.state.value}
                  className="col-12"
                  onChange={this.onChange}
                  placeholder='Enter First name' />

• Using Hooks React > 16.8 in functional style components:

[value, setValue] = useState('');
<input type='text'
                  name='firstName'
                  value={value}
                  className="col-12"
                  onChange={this.onChange}
                  placeholder='Enter First name' />

• If Using propTypes and providing Default Value for propTypes in case of HOC component in functional style.

 HOC.propTypes = {
    value       : PropTypes.string
  }
  HOC.efaultProps = {
    value: ''
  }

function HOC (){

  return (<input type='text'
                  name='firstName'
                  value={this.props.value}
                  className="col-12"
                  onChange={this.onChange}
                  placeholder='Enter First name' />)

}

Answer 19

Using React Hooks also don't forget to set the initial value.
I was using <input type='datetime-local' value={eventStart} /> and initial eventStart was like

const [eventStart, setEventStart] = useState();
instead
const [eventStart, setEventStart] = useState('');.

The empty string in parentheses is difference.
Also, if you reset form after submit like i do, again you need to set it to empty string, not just to empty parentheses.

This is just my small contribution to this topic, maybe it will help someone.

Answer 20

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

Solution : Check if value is not undefined

React / Formik / Bootstrap / TypeScript

example :

{ values?.purchaseObligation.remainingYear ?
  <Input
   tag={Field}
   name="purchaseObligation.remainingYear"
   type="text"
   component="input"
  /> : null
}

Answer 21

In addition to the accepted answer, if you're using an input of type checkbox or radio, I've found I need to null/undefined check the checked attribute as well.

<input
  id={myId}
  name={myName}
  type="checkbox" // or "radio"
  value={myStateValue || ''}
  checked={someBoolean ? someBoolean : false}
  />

And if you're using TS (or Babel), you could use nullish coalescing instead of the logical OR operator:

value={myStateValue ?? ''}
checked={someBoolean ?? false}

Answer 22

If you use multiple input in on field, follow: For example:

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

     this.state = {
       fields: { UserName: '', Password: '' }
     };
   }

   onChangeField = event => {
    let name = event.target.name;
    let value = event.target.value;
    this.setState(prevState => {
        prevState.fields[name] =  value;
        return {
           fields: prevState.fields
        };
    });
  };

  render() { 
     const { UserName, Password } = this.state.fields;
     return (
         <form>
             <div>
                 <label htmlFor="UserName">UserName</label>
                 <input type="text" 
                        id='UserName' 
                        name='UserName'
                        value={UserName}
                        onChange={this.onChangeField}/>
              </div>
              <div>
                  <label htmlFor="Password">Password</label>
                  <input type="password" 
                         id='Password' 
                         name='Password'
                         value={Password}
                         onChange={this.onChangeField}/>
              </div>
         </form>
     ); 
  }
}

Search your problem at:

onChangeField = event => {
    let name = event.target.name;
    let value = event.target.value;
    this.setState(prevState => {
        prevState.fields[name] =  value;
        return {
            fields: prevState.fields
        };
    });
};

Answer 23

In my case it was pretty much what Mayank Shukla's top answer says. The only detail was that my state was lacking completely the property I was defining.

For example, if you have this state:

state = {
    "a" : "A",
    "b" : "B",
}

If you're expanding your code, you might want to add a new prop so, someplace else in your code you might create a new property c whose value is not only undefined on the component's state but the property itself is undefined.

To solve this just make sure to add c into your state and give it a proper initial value.

e.g.,

state = {
    "a" : "A",
    "b" : "B",
    "c" : "C", // added and initialized property!
}

Hope I was able to explain my edge case.

Answer 24

const [name, setName] = useState()

generates error as soon as you type in the text field

const [name, setName] = useState('') // <-- by putting in quotes 

will fix the issue on this string example.

Answer 25

Changing value to defaultValue will resolve it.

Note:

defaultValue is only for the initial load. If you want to initialize the input then you should use defaultValue, but if you want to use state to change the value then you need to use value. Read this for more.

I used value={this.state.input ||""} in input to get rid of that warning.

Answer 26

The reason is, in state you defined:

this.state = { fields: {} }

fields as a blank object, so during the first rendering this.state.fields.name will be undefined, and the input field will get its value as:

value={undefined}

Because of that, the input field will become uncontrolled.

Once you enter any value in input, fields in state gets changed to:

this.state = { fields: {name: 'xyz'} }

And at that time the input field gets converted into a controlled component; that's why you are getting the error:

A component is changing an uncontrolled input of type text to be controlled.

Possible Solutions:

1- Define the fields in state as:

this.state = { fields: {name: ''} }

2- Or define the value property by using Short-circuit evaluation like this:

value={this.state.fields.name || ''}   // (undefined || '') = ''

Answer 27

SIMPLY, You must set initial state first

If you don't set initial state react will treat that as an uncontrolled component

Answer 28

Set Current State first ...this.state

Its because when you are going to assign a new state it may be undefined. so it will be fixed by setting state extracting current state also

this.setState({...this.state, field})

If there is an object in your state, you should set state as follows, suppose you have to set username inside the user object.

this.setState({user:{...this.state.user, ['username']: username}})