I new to React. I have two input fields which are filled when the pages loads via axios but when I want to change the Values I am unable to change them even I can not type anything on them.
function MainView() {
const [InputFields, setInputFields] = useState({
name: "",
fullURL: "",
});
const changeHandler = (e) => {
setInputFields({
...InputFields,
[e.target.name]: e.target.value,
});
};
const [links, setLinks] = useState([]);
const getLinks = () => {
axios.get('../sanctum/csrf-cookie').then(response => {
axios.get("/userlinks/getdata").then((res) => {
console.log(res);
setLinks(res.data);
}).catch((err) => {
console.log(err);
});
});
};
useEffect(() => {
getLinks();
}, []);
return (<div>
{links.map((link) => {
return (<div className="card" key={link.id}>
<form>
<input className="form-control" value={link.name} type="text" name="name" placeholder="name" onChange={changeHandler} />
<input className="form-control" value={link.fullURL} type="text" name="fullURL" placeholder="fullURL" onChange={changeHandler} />
</form>
</div>);
})}
</div>
);
}
export default MainView;
This happens because in your onChange method, you are changing InputFields variable, where as your getLinks method changes links variable, which is being rendered on the screen.
If you want to set an initial value, and then allow the user to change it, change your input to :
<input className="form-control" defaultValue={link.name}
value={InputFields.name} type="text" name="name" placeholder="name" onChange={changeHandler} />
Likewise change for your other input, if you do not want the user to change the value later on, it's often better to add disable in the input to avoid confusing people. 🙂
I know that this has been done so that you can create a minimal reproducible example for us, but I would have directly called setInputFields in the axios.get section to avoid this problem in the first place, however, if not possible, use the defaultValue and value as I've shown above.
This is my code:
<Input
onChange={(e) => someChange(e)}
valid={check.length !== 0}
invalid={check.length === 0}
type="text"
name="name"
id="name"
placeholder={something}
value={props.someProp ? props.user.name : ''}
/>
So what happens here is when I enter into props.someProp my value gets retrieved. The problem is that I cannot edit that field. Please note that user object gets populated when this screen appears.
How can I make some kind of sanity check so I still get the value populated, but I can edit it afterwards?
Thanks.
If you're using stateless components AND React 16.8+, use hooks. This will allow your stateless component to contain state. React calls these function components.
You might have previously known these as “stateless components”. We’re now introducing the ability to use React state from these, so we prefer the name “function components”.
Example
const Foo = props => {
const [name, someChange] = useState(props.someProp ? props.user.name : '');
return (
<Input
onChange={(e) => someChange(e.target.value)}
value={name}
...
/>
);
}
Documentation on hooks can be found here.
Set the initial state on component mount. After that the inputed value will be set on onChange.
constructor(props){
super(props);
this.state({name:''});
}
componentDidMount(){
this.setState({name: props.someProp ? props.user.name : ''});
}
someChange(e){
let name = e.target.name;
this.setState({[name]: e.target.value});
}
<Input
onChange={(e) => someChange(e)}
valid={check.length !== 0}
invalid={check.length === 0}
type="text"
name="name"
id="name"
placeholder={something}
value={this.state.name}
/>
I have the following code which is intended to get the input fed to ToggleForm component (which is a form) and store it in employeeData state. However, the problem is that whenever I press the submit button of ToggleForm for the first time after execution, "" value gets stored first in the employeeData state and it is only after I click the submit button for the second time that the data fed in the form comes to employeeData.
This must be a minor mistake. But I am not being able to figure it out.
import React from "react";
import ToggleForm from "./ToggleForm";
let employee = "";
class Home extends React.Component {
constructor(){
super();
this.state = {
employeeData: ""
};
}
addEmployee(e) {
e.preventDefault();
let name = e.target.name.value;
let address = e.target.address.value;
let salary = e.target.salary.value;
this.setState({
employeeData: [...this.state.employeeData, { name, address, salary }]
});
employee = [...this.state.employeeData];
console.log(employee);
}
render() {
return (
<div className="container">
<ToggleForm addEmployee={this.addEmployee.bind(this)}/>
</div>
);
}
}
export default Home;
Here is the ToggleForm component:
import React from 'react';
class ToggleForm extends React.Component {
render(){
return(<div>
<br/>
<h3>Add a new employee</h3>
<hr/>
<form className="form-group" onSubmit = {this.props.addEmployee}>
<input className="form-control" type="text" name="name" placeholder="Name of the employee"/><br/>
<input className="form-control" type="text" name="address" placeholder="Address of the employee"/><br/>
<input className="form-control" type="text" name="salary" placeholder="Salary of the employee"/><br/>
<input type="submit" className="btn btn-primary"/>
</form>
</div>)
}
}
export default ToggleForm;
setState is async and fortunately accepts an optional callback. Using the callback, you can access the most current value of state.
this.setState({
employeeData: [...this.state.employeeData, { name, address, salary }]
}, () => {
employee = [...this.state.employeeData];
});
Because setState is async so your need to setState in the component Toggle form when the text is change before ship it the parent component.
For example:
<input
onChange={this.handleChange}
className="form-control"
type="text"
name="name"
value={this.state.name}
placeholder="Name of the employee"
/>
<br />
Function handleChange:
handleChange = (e) => {
this.setState({ [e.target.name]: e.target.value });
console.log(e.target.value)
};
And then ship it to the parent:
handleSubmit = e => {
e.preventDefault();
const { name, address, salary } = this.state;
this.props.addEmployee({ name, address, salary });
};
Check my code here: https://codesandbox.io/s/ww5331jrxl
There are few basic correction in your components:
User super(); in the constructor before this.setState();
If you are not using this.state.employeeData, then don't set it in the state.
If you set the state then you will get the employeeData in the callback function as described by #Andy or you can use the following:
employee = [...this.state.employeeData, { name, address, salary }]
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>
)
}
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 || '') = ''
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.
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"
/>
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}
SIMPLY, You must set initial state first
If you don't set initial state react will treat that as an uncontrolled component
that's happen because the value can not be undefined or null to resolve you can do it like this
value={ this.state.value ?? "" }
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.
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('')
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}})
Best way to fix this is to set the initial state to ''.
constructor(props) {
super(props)
this.state = {
fields: {
first_name: ''
}
}
this.onChange = this.onChange.bind(this);
}
onChange(e) {
this.setState({
fields:{
...this.state.fields,
[e.target.name]: e.target.value
}
})
}
render() {
return(
<div className="form-group">
<input
value={this.state.fields.first_name}
onChange={this.onChange}
className="form-control"
name="first_name" // Same as state key
type="text"
refs="name"
placeholder="Name *"
/>
<span style={{color: "red"}}>{this.state.errors.first_name}</span>
</div>
)
}
Then you can still run your checks like if (field) and still achieve the same result if you have the value as ''.
Now since your value is now classified as type string instead of undefined after evaluation. Thus, clearing the error from the console of a big red block 😁😎.
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.
Put empty value if the value does not exist or null.
value={ this.state.value || "" }
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 ?? ''}
/>
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.
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
};
});
};
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.
like this
value={this.state.fields && this.state.fields["name"] || ''}
work for me.
But I set initial state like this:
this.state = {
fields: [],
}
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})
}
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
}
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>
)
}
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' />)
}
Change this
const [values, setValues] = useState({intialStateValues});
for this
const [values, setValues] = useState(intialStateValues);
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.
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;
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.
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)}
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>
I am new to react and i think it is a silly question to ask but then too
I have a generic input component of text field in which i haven't passed refs and i want to reset the value of text field on button click? Is it possible to clear the value of field on click without passing refs?
handleClick : function(change){
change.preventDefault();
var self=this;
if(this.state.newpwd === this.state.cfmpass){
var pass = {"pwd":self.state.newpwd};
var url = "xyz"
Request.PatchRequest(url,pass,function(response){
self.setState({
authMsg : JSON.parse(response.response).data
});
now how to clear the field value here??
<TextBox type="password"
name="password"
placeholder="Enter new password"
onChange={this.changePwd} />
this is my button on which i want to perform check (which i have done) and after response i want to clear the field value
<Button type="button"
value="Change"
onClick={this.handleClick}/>
TextBox is my generic component..
Any help will be very thankful.
Thank you in advance :)
You will need a component's prop that 'control' the input's value with onChange function. You'll need to do some steps:
Add inside your constructor method the input's value initial state, most cases uses a empty string
Make your onChange function set a new state for that value
Do not forget to bind your function inside constructor
For even more details, you can copy and paste your components code, to confirm your react syntax (es5, es6 or es7)
Example:
constructor() {
this.state: {
value: ''
this.changePwd = this.changePwd.bind(this)
}
changePwd(event) {
this.setState({ value: event.target.value })
}
<TextBox
type="password"
name="password"
placeholder="Enter new password"
value={this.state.value}
onChange={this.changePwd}
/>
This approach assumes the parent component (the thing that holds both the textarea and the button) is maintaining the state of the textarea (which in this case, would be the way to do it)
// somewhere within the component (probably the container component)
reset() {
this.setState({ value: '' });
}
onChange(e) {
this.setState({ value: e.target.value });
}
// render
<TextBox
type="password"
name="password"
placeholder="Enter new password"
onChange={this.onChange}
value={this.state.value}
/>
<button onClick={this.reset}>reset</button>
EDIT Updated based on an updated question...
constructor(props) {
super(props);
this.change = this.change.bind(this);
this.inputOnChange = this.inputOnChange.bind(this);
}
change(e) {
e.preventDefault();
if(this.state.newpwd === this.state.cfmpass) {
var pass = {
"pwd": this.state.newpwd
};
var url = "xyz";
Request.PatchRequest(url, pass, (response) => {
this.setState({
authMsg : JSON.parse(response.response).data,
value: '',
});
});
}
inputOnChange(e) {
this.setState({ value: e.target.value });
}
// render
render() {
return (
<TextBox
type="password"
name="password"
placeholder="Enter new password"
onChange={this.inputOnChange}
value={this.state.value}
/>
<button onClick={this.change}>Change</button>
);
}