Javascript – React a component is changing an uncontrolled input of type checkbox to be controlled

javascriptreactjs

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.

Best Answer

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 || "" };

Related Solutions

Android – How to implement ClientLogin on Android to access Google services

There's nothing special you need to do; you can use the standard Java networking and built-in Apache Commons HTTP client library to make the HTTP requests.

You just implement the required requests, though note that you may need to handle the display of a CAPTCHA if Google asks you to.

As there are a few OAuth implementations for Android already, you could also try looking at Google's OAuth authentication mechanism — but it actually looks more complex and not as seamless...

Javascript – Detect click outside React component

Refs usage in React 16.3+ changed.

The following solution uses ES6 and follows best practices for binding as well as setting the ref through a method.

To see it in action:

Class Implementation:

import React, { Component } from 'react';
import PropTypes from 'prop-types';

/**
 * Component that alerts if you click outside of it
 */
export default class OutsideAlerter extends Component {
    constructor(props) {
        super(props);

        this.wrapperRef = React.createRef();
        this.setWrapperRef = this.setWrapperRef.bind(this);
        this.handleClickOutside = this.handleClickOutside.bind(this);
    }

    componentDidMount() {
        document.addEventListener('mousedown', this.handleClickOutside);
    }

    componentWillUnmount() {
        document.removeEventListener('mousedown', this.handleClickOutside);
    }

    /**
     * Alert if clicked on outside of element
     */
    handleClickOutside(event) {
        if (this.wrapperRef && !this.wrapperRef.current.contains(event.target)) {
            alert('You clicked outside of me!');
        }
    }

    render() {
        return <div ref={this.wrapperRef}>{this.props.children}</div>;
    }
}

OutsideAlerter.propTypes = {
    children: PropTypes.element.isRequired,
};

Hooks Implementation:

import React, { useRef, useEffect } from "react";

/**
 * Hook that alerts clicks outside of the passed ref
 */
function useOutsideAlerter(ref) {
    useEffect(() => {
        /**
         * Alert if clicked on outside of element
         */
        function handleClickOutside(event) {
            if (ref.current && !ref.current.contains(event.target)) {
                alert("You clicked outside of me!");
            }
        }

        // Bind the event listener
        document.addEventListener("mousedown", handleClickOutside);
        return () => {
            // Unbind the event listener on clean up
            document.removeEventListener("mousedown", handleClickOutside);
        };
    }, [ref]);
}

/**
 * Component that alerts if you click outside of it
 */
export default function OutsideAlerter(props) {
    const wrapperRef = useRef(null);
    useOutsideAlerter(wrapperRef);

    return <div ref={wrapperRef}>{props.children}</div>;
}

Related Topic