Just a note, this question is NOT an asynchronous update problem (at least, I don't think it is).
I have a class component with the following content (heavily simplified to get right to the issue):
constructor(props) {
super(props);
this.state = {
aSelected: false;
bSelected: false
}
}
handleCheckboxChange = (e) => {
const { checked, value } = e.target;
console.log( 'checked: ', checked );
if(value=="a") {
this.setState( {aSelected: checked}, () => {
console.log('aSelected: ', this.state.aSelected);
console.log("---")
});
}
if(value=="b") {
this.setState( {bSelected: checked}, () => {
console.log('bSelected: ', this.state.bSelected);
console.log("---")
});
}
}
Somewhere inside the render return, I have this:
<input>
type="checkbox"
value="a"
onChange={this.handleCheckboxChange}
checked={this.state.aSelected}
disabled={ (this.state.aSelected || (!this.state.aSelected && !this.state.bSelected) ) ? false : true}
</input>
<input>
type="checkbox"
value="b"
onChange={this.handleCheckboxChange}
checked={this.state.bSelected}
disabled={ (this.state.bSelected || (!this.state.aSelected && !this.state.bSelected) ) ? false : true}
</input>
Here is the output logged in Chrome Developer Tools. As you can see, "checked" is toggled appropriately each time I selected and unselect the checkbox. However, the state of "selected" (should say "aSelected") is never changed and always has the initial state value of false. Anyone know why the value of "selected" (should say "aSelected") is never changed?
Edit: My goal is to create two checkbox items, where the user can only select ONE or select NONE. While one is selected, the other should be disabled.
When you call setState to update the state, React re-renders the component, which resets the checkbox back to it's default (i.e. unchecked) state.
You'll need to use the current state to manage the checkbox as well. The JSX should look something like:
<input
type="checkbox"
checked={this.state.aSelected}
onChange={this.handleCheckboxChange}
/>
In React's terms, this is what's known as a "controlled component" because React is fully responsible for keeping up with the input's state. Read more in the docs here:
https://reactjs.org/docs/forms.html#controlled-components
vs
https://reactjs.org/docs/uncontrolled-components.html
Edit to match the question's edits:
In your render function, be sure you're using this.state.aSlected. Note, you also still need the checked={this.state.aChecked} attribute as well, otherwise the checkbox will be unchecked on the next render.
Like:
<input
type="checkbox"
value="a"
onChange={this.handleCheckboxChange}
checked={this.state.aSelected}
// added for clarification *
disabled={this.state.aSelected || (!this.state.aSelected && !this.state.bSelected) ? false : true}
/>
Edit with Working Example
Here's a working CodeSandbox example where checking one checkbox disables the other:
class CheckboxComponent extends React.Component {
constructor(props) {
super(props);
this.state = {
aSelected: false,
bSelected: false
};
}
handleCheckbox = (event) => {
if (event.target.name === "boxA") {
this.setState({ aSelected: event.target.checked });
} else if (event.target.name === "boxB") {
this.setState({ bSelected: event.target.checked });
}
};
render() {
let aDisabled = this.state.bSelected && !this.state.aSelected;
let bDisabled = this.state.aSelected && !this.state.bSelected;
return (
<div>
<label>
<input
type="checkbox"
name="boxA"
checked={this.state.aSelected}
onChange={this.handleCheckbox}
disabled={aDisabled}
/>
Checkbox A
</label>
<br />
<br />
<label>
<input
type="checkbox"
name="boxB"
checked={this.state.bSelected}
onChange={this.handleCheckbox}
disabled={bDisabled}
/>
Checkbox B
</label>
</div>
);
}
}
I need to trigger a function when the value of Hidden input/textArea/TextField changing in React. Not when the user enter values. When dynamically changing the hidden input value trigger a function.
import TextField from "#material-ui/core/TextField";
class RowComponent extends Component {
constructor(props) {
super(props);
this.state = {
xx: "",
salary: 0,
};
}
handleChange = (event) => {
this.setState({
xx: event.target.value,
});
};
render() {
const {
member: { salary },
} = this.props;
console.log(this.state.xx);
return (
<TextField
name="HiddenField"
type="hidden"
value={this.state.salary !== 0 ? this.state.salary : salary}
onChange={this.handleChange}
/>
);
}
}
onChange will not trigger here because it will only fire when the user changes the value of the input field (e.g., user types in a new character).
Based on the logic of your app, It looks like the value of TextField will only be controlled by the prop as long as the RowComponent salary state is not equal to 0 (based off of this condition on your TextField: value={this.state.salary !== 0 ? this.state.salary : salary}) - and this is evident and is much more clear when you browse the state/props with React Dev Tools.
So, what you can do is compare the previous props & state with the current ones & assess whether or not to update the state xx
componentDidUpdate(prevProps, prevState) {
if (prevProps.member.salary !== this.props.member.salary) {
if (this.state.salary === 0) {
this.setState(
{
xx: this.props.member.salary
},
() => {
console.log("new xx", this.state.xx);
}
);
}
}
if (prevState.salary !== this.state.salary) {
this.setState(
{
xx: this.state.salary
},
() => {
console.log("new xx", this.state.xx);
}
);
}
}
react gives me a warning: "A component is changing an uncontrolled input of type checkbox to be controlled. Input elements should not switch from uncontrolled to controlled (or vice versa)."
However my checbox is change via the state property. Am I missing something obvious?
import React from 'react';
// Components
import Checkbox from './checkbox';
import HelpBubble from './helpBubble';
export default class CheckboxField extends React.Component {
constructor(props) {
super(props);
this.state = {value: props.value};
this.handleChange = this.handleChange.bind(this);
}
handleChange(event) {
this.setState({value: event.target.value});
}
componentWillReceiveProps(nextProps) {
if (nextProps.value !== this.props.value) {
this.setState({value: nextProps.value});
}
}
render() {
const {label, meta = {}, help, disabled, required, onChange} = this.props;
return (
<label className="checkbox-wrap form-field">
<Checkbox
disabled={disabled}
type="checkbox"
onChange={(event) => {
onChange(event, !this.state.value);
}}
checked={this.state.value}/>
{label && (
<div className="checkbox-label">
{label}
{required && <div className="form-field__required"/>}
</div>
)}
{help && <HelpBubble help={help}/>}
{meta.error && meta.touched && (
<div className="input-error">{meta.error}</div>
)}
</label>
);
}}
Parent component:
handleChangeParams(key, value)
}
/>
Handle change params changes the value in model and calls server. Depending on server result, the value can change.
Thanks in advance.
If your state is initialized with props.value being null React will consider your Checkbox component to be uncontrolled.
Try setting your initial state so that value is never null.
this.state = { value: props.value || "" };
If you are using a checkbox react won't like a string either so instead try
this.state = { checkboxValue: props.checkboxValue || false };
Something worth noting about the above code snippet. When you set a state in the constructor from props, it is always best to set the state to a "controlled" value i.e. a tangible value such as an int, float, string, array, map, etc. The error you are getting is the result of props.value being set to null
So, Consider setting your constructor state like this:
this.state = {
value: props.value ? props.value : 'empty'
}
What is happening here is it is checking if props.value has a value, if it does it sets the state to props.value, if props.value is null, it sets the state to the string: `'empty'
Another simple way to do this would be to !! your props.checkboxValue value. That way even if it's undefined, !!props.checkboxValue will resolve to false.
this.state = { checkboxValue: !!props.checkboxValue };
In my case, I was using a prop from my redux store to set whether the checkbox was checked, simply defaulting the property to false worked for me.
e.g.
const MyComponent = ({
somePropFromRedux
}) => {
return <thatThridPartyCheckboxComponent checked={somePropFromRedux} />
}
becomes (only change is adding = false on Line 2)
const MyComponent = ({
somePropFromRedux = false
}) => {
return <thatThridPartyCheckboxComponent checked={somePropFromRedux} />
}
do not use e.target.checked in the inputbox onChange eventHandler method.
Correct way:
const [isChecked, setCheck] = useState(false);
const handler = (e) => {
setCheck(!isChecked);
};
<input
type="checkbox"
checked={isChecked}
onChange={handler}
/>
I'm trying to render a list of inputs in react and bind the input values to an array. I'm also trying to make it so the list items are removable. However, when I remove an item from the array, the input items are not updated how I would expect. Instead of removing the input that was removed from the middle of the array, the last input is removed and the middle input remains.
var Inputs = React.createClass({
getInitialState: function() {
return {
inputarr: ['']
};
},
render: function() {
var self = this;
return <div>{ this.state.inputarr.map(function (value, i) {
return <div key={i}><input onChange={function (e) {self.onChangeInput(i, e)}}/>
{ i < (self.state.inputarr.length - 1) && <button onClick={function () {self.onRemove(i)}}>x</button>}
</div>;
}) }</div>;
},
onChangeInput: function (i, e) {
this.state.inputarr[i] = e.target.value;
if (this.state.inputarr[this.state.inputarr.length - 1] !== '') {
this.state.inputarr.push('');
}
this.setState({
inputarr: this.state.inputarr.slice(0)
});
},
onRemove: function (i) {
this.state.inputarr.splice(i, 1);
this.setState({
inputarr: this.state.inputarr.slice(0)
});
}
});
ReactDOM.render(
<Inputs/>,
document.getElementById('container')
);
You can run this in this fiddle: https://jsfiddle.net/vvd7hex9/1/
What happens?
add something to the first input, a second will appear. Type in 3 different inputs.
remove the second input using the x button.
The last input is removed.
What I expected to happen
The middle input to be removed and only 2 inputs should contain the contents in the inputarr array.
Why does this happen? How can I fix it to remove the correct input?
Ahhhh, this is a classic javascript problem. It has to do with your map statement. You can read more about the specific details here, but what it boils down to is that when the click events actually fire, the value of i is equal to inputarr.length - 1. To fix this, you need some way of preserving the value of i during each loop. The easiest way to do this is to change the click event to this:
<button onClick={self.onRemove(i)}>x</button>
and change onRemove to this:
onRemove: function (i) {
var self = this;
return function(e) {
self.state.inputarr.splice(i, 1);
self.setState({
inputarr: this.state.inputarr.slice(0)
});
}
}
Some more info about closures can be found here if you're unfamiliar
I think it would be better to have separate Input component and App component.
Then you can create increment and decrement methods and pass them down from App to your Input components. I have build a little pen to show how you can achieve it.
I used some useful methods from lodash so take a look how them work.
https://codepen.io/dagman/pen/oYaYyL
The code itself.
class App extends React.Component {
constructor(props) {
super(props);
this.increment = this.increment.bind(this);
this.decrement = this.decrement.bind(this);
this.state = {
quantity: [0],
};
}
increment(value) {
const { quantity } = this.state;
this.setState({
quantity: quantity.concat(_.last(quantity) + 1),
});
}
decrement(el) {
const { quantity } = this.state;
this.setState({ quantity: _.without(quantity, el) })
}
render() {
const inputs = this.state.quantity.map(x => (
<Input
increment={this.increment}
decrement={this.decrement}
key={x}
toDelete={x}
/>
));
return (
<form>
{inputs}
</form>
);
}
}
class Input extends React.Component {
constructor(props) {
super(props);
this.onChange = this.onChange.bind(this);
this.onBtnClick = this.onBtnClick.bind(this);
this.state = {
value: '',
shouldIncrementQuantity: true,
};
}
onChange(e) {
const value = e.target.value;
this.setState({ value });
if(value.trim().length > 0 && this.state.shouldIncrementQuantity) {
this.setState({
shouldIncrementQuantity: false,
}, () => this.props.increment());
}
}
onBtnClick(e) {
e.preventDefault();
this.props.decrement(this.props.toDelete);
}
render() {
return (
<p className="input-field">
<input
type="text"
value={this.state.value}
onChange={this.onChange}
/>
<button onClick={this.onBtnClick}>x</button>
</p>
);
}
}
ReactDOM.render(
<App />,
document.getElementById('root')
);
I have a simple react component with the form which I believe to have one controlled input:
import React from 'react';
export default class MyForm extends React.Component {
constructor(props) {
super(props);
this.state = {}
}
render() {
return (
<form className="add-support-staff-form">
<input name="name" type="text" value={this.state.name} onChange={this.onFieldChange('name').bind(this)}/>
</form>
)
}
onFieldChange(fieldName) {
return function (event) {
this.setState({[fieldName]: event.target.value});
}
}
}
export default MyForm;
When I run my application I get the following warning:
Warning: MyForm 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
I believe my input is controlled since it has a value. I am wondering what am I doing wrong?
I am using React 15.1.0
I believe my input is controlled since it has a value.
For an input to be controlled, its value must correspond to that of a state variable.
That condition is not initially met in your example because this.state.name is not initially set. Therefore, the input is initially uncontrolled. Once the onChange handler is triggered for the first time, this.state.name gets set. At that point, the above condition is satisfied and the input is considered to be controlled. This transition from uncontrolled to controlled produces the error seen above.
By initializing this.state.name in the constructor:
e.g.
this.state = { name: '' };
the input will be controlled from the start, fixing the issue. See React Controlled Components for more examples.
Unrelated to this error, you should only have one default export. Your code above has two.
When you first render your component, this.state.name isn't set, so it evaluates to undefined or null, and you end up passing value={undefined} or value={null}to your input.
When ReactDOM checks to see if a field is controlled, it checks to see if value != null (note that it's !=, not !==), and since undefined == null in JavaScript, it decides that it's uncontrolled.
So, when onFieldChange() is called, this.state.name is set to a string value, your input goes from being uncontrolled to being controlled.
If you do this.state = {name: ''} in your constructor, because '' != null, your input will have a value the whole time, and that message will go away.
Another approach it could be setting the default value inside your input, like this:
<input name="name" type="text" value={this.state.name || ''} onChange={this.onFieldChange('name').bind(this)}/>
I know others have answered this already. But a very important factor here that may help other people experiencing similar issue:
You must have an onChange handler added in your input field (e.g. textField, checkbox, radio, etc). Always handle activity through the onChange handler.
Example:
<input ... onChange={ this.myChangeHandler} ... />
When you are working with checkbox you may need to handle its checked state with !!.
Example:
<input type="checkbox" checked={!!this.state.someValue} onChange={.....} >
Reference: https://github.com/facebook/react/issues/6779#issuecomment-326314716
Simple solution to resolve this problem is to set an empty value by default :
<input name='myInput' value={this.state.myInput || ''} onChange={this.handleChange} />
One potential downside with setting the field value to "" (empty string) in the constructor is if the field is an optional field and is left unedited. Unless you do some massaging before posting your form, the field will be persisted to your data storage as an empty string instead of NULL.
This alternative will avoid empty strings:
constructor(props) {
super(props);
this.state = {
name: null
}
}
...
<input name="name" type="text" value={this.state.name || ''}/>
I had the same problem.
the problem was when i kept the state info blank
const [name, setName] = useState()
I fixed it by adding empty string like this
const [name, setName] = useState('')
In my case, I was missing something really trivial.
<input value={state.myObject.inputValue} />
My state was the following when I was getting the warning:
state = {
myObject: undefined
}
By alternating my state to reference the input of my value, my issue was solved:
state = {
myObject: {
inputValue: ''
}
}
When you use onChange={this.onFieldChange('name').bind(this)} in your input you must declare your state empty string as a value of property field.
incorrect way:
this.state ={
fields: {},
errors: {},
disabled : false
}
correct way:
this.state ={
fields: {
name:'',
email: '',
message: ''
},
errors: {},
disabled : false
}
If the props on your component was passed as a state, put a default value for your input tags
<input type="text" placeholder={object.property} value={object.property ? object.property : ""}>
Set a value to 'name' property in initial state.
this.state={ name:''};
An update for this. For React Hooks use const [name, setName] = useState(" ")
Simply create a fallback to '' if the this.state.name is null.
<input name="name" type="text" value={this.state.name || ''} onChange={this.onFieldChange('name').bind(this)}/>
This also works with the useState variables.
I believe my input is controlled since it has a value.
Now you can do this two ways the best way is to have a state key to each input with 1 onChange handler. If you have checkboxes you will need to write a separate onChange handler.
With a Class component you would want to write it like this 👇
import React from 'react';
export default class MyForm extends React.Component {
constructor(props) {
super(props);
this.state = {
myFormFields: {
name: '',
dob: '',
phone: ''
}
}
this.onFormFieldChange = this.onFormFieldChange.bind(this)
}
// Always have your functions before your render to keep state batches in sync.
onFormFieldChange(e) {
// No need to return this function can be void
this.setState({
myFormFields: {
...this.state.myFormFields,
[e.target.name]: e.target.value
}
})
}
render() {
// Beauty of classes we can destruct our state making it easier to place
const { myFormFields } = this.state
return (
<form className="add-support-staff-form">
<input name="name" type="text" value={myFormFields.name} onChange={this.onFormFieldChange}/>
<input name="dob" type="date" value={myFormFields.dob} onChange={this.onFormFieldChange}/>
<input name="phone" type="number" value={myFormFields.phone} onChange={this.onFormFieldChange}/>
</form>
)
}
}
export default MyForm;
Hope that helps for a class but the most performative and what the newest thing the devs are pushing everyone to use is Functional Components. This is what you would want to steer to as class components don't intertwine well with the latest libraries as they all use custom hooks now.
To write as a Functional Component
import React, { useState } from 'react';
const MyForm = (props) => {
// Create form initial state
const [myFormFields, setFormFields] = useState({
name: '',
dob: '',
phone: ''
})
// Always have your functions before your return to keep state batches in sync.
const onFormFieldChange = (e) => {
// No need to return this function can be void
setFormFields({
...myFormFields,
[e.target.name]: e.target.value
})
}
return (
<form className="add-support-staff-form">
<input name="name" type="text" value={myFormFields.name} onChange={onFormFieldChange}/>
<input name="dob" type="date" value={myFormFields.dob} onChange={onFormFieldChange}/>
<input name="phone" type="number" value={myFormFields.phone} onChange={onFormFieldChange}/>
</form>
)
}
export default MyForm;
Hope this helps! 😎
In short, if you are using class component you have to initialize the input using state, like this:
this.state = { the_name_attribute_of_the_input: "initial_value_or_empty_value" };
and you have to do this for all of your inputs you'd like to change their values in code.
In the case of using functional components, you will be using hooks to manage the input value, and you have to put initial value for each input you'd like to manipulate later like this:
const [name, setName] = React.useState({name: 'initialValue'});
If you'd like to have no initial value, you can put an empty string.
In my case component was rerendering and throwing A component is changing an uncontrolled input of type checkbox to be controlled error. It turned out that this behaviour was a result of not keeping true or false for checkbox checked state (sometimes I got undefined). Here what my faulty component looked like:
import * as React from 'react';
import { WrappedFieldProps } from 'redux-form/lib/Field';
type Option = {
value: string;
label: string;
};
type CheckboxGroupProps = {
name: string;
options: Option[];
} & WrappedFieldProps;
const CheckboxGroup: React.FC<CheckboxGroupProps> = (props) => {
const {
name,
input,
options,
} = props;
const [value, setValue] = React.useState<string>();
const [checked, setChecked] = React.useState<{ [name: string]: boolean }>(
() => options.reduce((accu, option) => {
accu[option.value] = false;
return accu;
}, {}),
);
React.useEffect(() => {
input.onChange(value);
if (value) {
setChecked({
[value]: true, // that setChecked argument is wrong, causes error
});
} else {
setChecked(() => options.reduce((accu, option) => {
accu[option.value] = false;
return accu;
}, {}));
}
}, [value]);
return (
<>
{options.map(({ value, label }, index) => {
return (
<LabeledContainer
key={`${value}${index}`}
>
<Checkbox
name={`${name}[${index}]`}
checked={checked[value]}
value={value}
onChange={(event) => {
if (event.target.checked) {
setValue(value);
} else {
setValue(undefined);
}
return true;
}}
/>
{label}
</LabeledContainer>
);
})}
</>
);
};
To fix that problem I changed useEffect to this
React.useEffect(() => {
input.onChange(value);
setChecked(() => options.reduce((accu, option) => {
accu[option.value] = option.value === value;
return accu;
}, {}));
}, [value]);
That made all checkboxes keep their state as true or false without falling into undefined which switches control from React to developer and vice versa.
For people using Formik, you need to add a default value for the specific field name to the form's initialValues.
This generally happens only when you are not controlling the value of the filed when the application started and after some event or some function fired or the state changed, you are now trying to control the value in input field.
This transition of not having control over the input and then having control over it is what causes the issue to happen in the first place.
The best way to avoid this is by declaring some value for the input in the constructor of the component.
So that the input element has value from the start of the application.
Please try this code
import React from "react";
class MyForm extends React.Component {
constructor(props) {
super(props);
this.state = { name: "" };
this.onFieldChange = this.onFieldChange.bind(this);
}
onFieldChange(e) {
this.setState({[e.target.name]: e.target.value});
}
render() {
return (
<form className="add-support-staff-form">
<input name="name" type="text" value={this.state.name} onChange={this.onFieldChange} />
</form>
);
}
}
export default MyForm;
In my case there was spell mistake while setting the state which was causing defined value to be undefined.
This is my default state with value
const [email, setEmail] = useState(true);
my mistake was-
setEmail(res?.data?.notificationSetting.is_email_notificatio);
and the solution is -
setEmail(res?.data?.notificationSetting.is_email_notification);
last char was missing
I had the same issue with type='radio'
<input type='radio' checked={item.radio} ... />
the reason was that item.radio is not always true or false, but rather true or undefined, for example. Make sure it’s always boolean, and the problem will go away.
<input type='radio' checked={!!item.radio} ... />
source
For dynamically setting state properties for form inputs and keeping them controlled you could do something like this:
const inputs = [
{ name: 'email', type: 'email', placeholder: "Enter your email"},
{ name: 'password', type: 'password', placeholder: "Enter your password"},
{ name: 'passwordConfirm', type: 'password', placeholder: "Confirm your password"},
]
class Form extends Component {
constructor(props){
super(props)
this.state = {} // Notice no explicit state is set in the constructor
}
handleChange = (e) => {
const { name, value } = e.target;
this.setState({
[name]: value
}
}
handleSubmit = (e) => {
// do something
}
render() {
<form onSubmit={(e) => handleSubmit(e)}>
{ inputs.length ?
inputs.map(input => {
const { name, placeholder, type } = input;
const value = this.state[name] || ''; // Does it exist? If so use it, if not use an empty string
return <input key={name} type={type} name={name} placeholder={placeholder} value={value} onChange={this.handleChange}/>
}) :
null
}
<button type="submit" onClick={(e) => e.preventDefault }>Submit</button>
</form>
}
}