Uncontrolled input React Hooks

Question

I've started learing about react-hooks with a simple tutorial and to my surprise I got an error that I cannot figure out:

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.

After this error, my component disappears but I still can input data that will correctly print out in console.

I've tried setting initial state for inputs and changing

setInputs(inputs => ({
  ...inputs, [event.target.name]: event.target.value
}));

to

setInputs({...inputs, [event.target.name]: event.target.value});

but I'm still getting error.

JSX

import React from 'react';
import './styles/form.scss';
import useSignUpForm from './hooks/customHooks.jsx';

const Form = () => {

    const {inputs, handleInputChange, handleSubmit} = useSignUpForm();

    return (
        <React.Fragment>
            <div className="formWrapper">
                <h1 className="header">Form</h1>
                <form onSubmit={handleSubmit}>
                    <div className="form-group">
                        <label htmlFor="nicknameInput">Nickname</label>
                        <input type="text" id="nicknameInput" name="nickname" onChange={handleInputChange}
                               value={inputs.nickname} required/>

                        <label htmlFor="emailInput">Email Address</label>
                        <input type="text" id="emailInput" name="email" onChange={handleInputChange}
                               value={inputs.email} required/>

                        <label htmlFor="lastName">Last Name</label>
                        <input type="text" id="lastName" name="lastName" onChange={handleInputChange}
                               value={inputs.lastName} required/>
                    </div>
                    <button type="submit" className="btn btn-primary">Submit</button>
                </form>
            </div>
        </React.Fragment>
    )
};

export default Form;

Hooks

import React, {useState} from 'react';

const useSignUpForm = (callback) => {
    const [inputs, setInputs] = useState({});
    console.log(inputs);

    const handleSubmit = (event) => {
        if (event) {
            event.preventDefault();
        }
    };

    const handleInputChange = (event) => {
        event.persist();
        setInputs(inputs => ({
                ...inputs, [event.target.name]: event.target.value
            })
        );
    };

    return {
        handleSubmit,
        handleInputChange,
        inputs
    };

};

export default useSignUpForm;

Any ideas what causes this error?

Answer 1

You are getting the error, because your inputs start their life as undefined and then have a value. If you replace this const [inputs, setInputs] = useState({}); with this:

const [inputs, setInputs] = useState({
   nickname: '',
   lastname: '',
   email: ''
});

it will go away.