create separate react component for cookie management

I have a component which renders if its prop.paramA is different from paramA value stored in cookie.

Following is my attempt to move the cookie management logic into a separate component. The problem is that the question component gets rendered only once when showQuestion is false so I never get to see the question.

Currently, my code looks like below

// question.js
import React from 'react';
import ToggleDisplay from 'react-toggle-display';
import {withCookies, Cookies} from 'react-cookie';

class Question extends React.Component {

    static get propTypes() {
        return {
            cookies: instanceOf(Cookies).isRequired
        }
    }

    constructor(props) {
        super(props);
        this.state = {
            paramA: props.paramA,
            showQuestion: props.showQuestion
        };
    }

    componentDidMount() {
        if (this.state.showQuestion) {
            // do some ajax calls etc.
        }
    }

    render() {
        return (
            <div id="simplequestion">
                <ToggleDisplay show={this.state.showQuestion}>
                    <div>What is your SO profile?</div>
                </ToggleDisplay>
            </div>
        );
    }
}

export default withCookies(Question);

I wrote following CookieManager component -

// cookiemanager.js
import React from 'react';
import {withCookies, Cookies} from 'react-cookie';

class CookieManager extends React.Component {
    static get propTypes() {
        return {
            cookies: instanceOf(Cookies).isRequired
        }
    }

    constructor(props) {
        super(props);
        let propA = props.cookies.get('propA');
        if (!propA || propA !== props.propA) {
            props.cookies.set('propA', props.propA, { path: '/', maxAge: 604800});
            console.log('changed', propA, props.propA);
            props.propAChanged(true);
        } else if (propA === props.propA) {
            console.log('unchanged', propA, props.propA);
            props.propAChanged(false);
        }
    }
    render() { 
        return <div id="cookieManager"></div>;
    }
}
export default withCookies(CookieManager);

Following is the top level app

// app.js
import React from 'react';
import Question from './question';
import CookieManager from './cookiemanager';
import { CookiesProvider } from 'react-cookie';


class App extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            paramA: props.paramA,
            showQuestion: false,
            avoidUpdate: false
        };
        this.updateShowQuestion = this.updateShowQuestion.bind(this);
    }

    updateShowQuestion(x) {
        if (this.state.avoidUpdate) {
            return;
        }
        this.setState({
            paramA: this.state.paramA,
            showQuestion: x,
            avoidUpdate: !this.state.avoidUpdate
        });
    }

    componentWillUpdate(nextProps, nextState) {
        if (!nextState.avoidUpdate && nextState.paramA === this.state.paramA) {
            this.setState({
                paramA: this.state.paramA,
                showQuestion: this.state.showQuestion,
                avoidUpdate: true
            });
        }
    }

    render() {
        return (
            <CookiesProvider>
                <CookieManager paramA={this.state.paramA} ridChanged={this.updateShowQuestion}>
                <Question
                    paramA={this.state.paramA}
                    showQuestion={this.state.showQuestion}/>
                </CookieManager>
            </CookiesProvider>
        );
    }
}
export default App;

Solution

You're reading from state here:

<ToggleDisplay show={this.state.showQuestion}>

But showQuestion is set only once, in the constructor:

this.state = {
    paramA: props.paramA,
    showQuestion: props.showQuestion
};

When this.props changes your component is rendered, but you're still reading from this.state which is not updated, so the visible output is the same.

I see two ways you can solve this:

Update this.state.showQuestion whenever the props change:

static getDerivedStateFromProps(nextProps, prevState) {
    if(nextProps.showQuestion !== prevState.showQuestion)
        return { showQuestion };
}

In render(), read from this.props.showQuestion:
```
<ToggleDisplay show={this.props.showQuestion}>
```
This way may look easier but with the other you gain more fine-grained control over state changes.

Another thing you've missed is found here:

componentWillUpdate(nextProps, nextState) {
    if (!nextState.avoidUpdate && nextState.paramA === this.state.paramA) {
        this.setState({
            paramA: this.state.paramA,
            showQuestion: this.state.showQuestion, // this line
            avoidUpdate: true
        });
    }
}

You're receiving new props, but you're setting the old state: showQuestion: this.state.showQuestion. Instead, set the new showQuestion value from the new props - nextProps, this way:

componentWillUpdate(nextProps, nextState) {
    if (!nextState.avoidUpdate && nextState.paramA === this.state.paramA) {
        this.setState({
            paramA: this.state.paramA,
            showQuestion: nextProps.showQuestion, // this line
            avoidUpdate: true
        });
    }
}