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Persist data between two pages with Next.js

I would like to refactor my Next.js webapp to have different pages handle different screens. Currently, I have this component holding several states to know in which screen I'm in. In the jsx section, I'm using {value && ... } to render the right component.
But I feel this is not good design, and won't be maintainable when adding more and more screens.
I would also like to avoid Redux as it is overkill for my project.
I was thinking about persisting data in cookies so I can retrieve them with getInitialProps in every component when rendering a new page, but is there a more elegant way?
I've read about tweaking the _app.js but I'm not sure to understand the consequences of doing so, and how it could help me..
Any suggestion?

When multiple of your pages need to make use of same data, you can make use of Context to store the result. It a good way to make a centralized storage without using complex and more self sufficient libraries like redux
You can implement context inside of _app.js file which must reside inside your root folder. This way next.js treats it as a root wrapper and you would just need to use 1 instance of Context
contexts/appContext
import React from 'react';
const AppContext = React.createContext();
export const AppProvider = AppContext.Provider;
export const AppConsumer = AppContext.Consumer;
export default AppContext;
_app.js
import React from 'react'
import App from 'next/app'
import AppProvider from '../contexts/appContext';
class MyApp extends App {
state={
data:[]
}
render() {
const { Component, pageProps } = this.props;
// You can implement logic in this component to fetch data and update state
return (
<div>
<AppProvider value={this.state.data}> // pass on value to context
<Component {...pageProps} />
</AppProvider>
</div>
)
}
}
export default MyApp
Now further each component can make use of context value by using AppConsumer or using useContext if you use hooks
Please read more about how to use Context here

React Context API not working from custom NPM component library

I've built a ReactJS component library that I use for multiple projects installed via an NPM package using a sim link. I want to use the context API to pass data from a parent component served from the component library to my base project to be consumed by multiple consumer components also served from the component library. When I try the context is always undefined in my child components.
If I place my consumer component in my provider component within my library it works like a champ but this defeats what I'm trying to achieve. If I export both the provider and the consumer to my base project the consumer doesn't see the provider.
This is from my base project
import { Screen, COD, GenericSocketServer } from 'component-library'
export default class View extends React.PureComponent {
render() {
return (
<Screen className="screen odmb1">
<GenericSocketServer>
<COD />
</GenericSocketServer>
</Screen>
)
}
}
This is my provider code exported from my 'component-library'
import React from 'react';
import MyContext from "./context";
import COD from './../cod';
export default class GenericSocketServer extends React.Component {
render() {
return (
<MyContext.Provider value={{ foo: 'bar' }}>
<COD />
{this.props.children}
</MyContext.Provider>
);
}
}
This is my content code used in 'component-library'
import React from 'react'
const MyContext = React.createContext()
export default MyContext
This is my consumer component exported from 'component-library'
import MyContext from "../GenericSocketServer/context"
class COD extends React.Component {
render() {
return (
<React.Fragment>
<MyContext.Consumer>
{(context) => {
/*
context comes back undefined
I expect { foo: 'bar' }
*/
console.log('context :', context)
return (
<p>This should work</p>
)}}
</MyContext.Consumer>
</React.Fragment>
)
}
}
Context always comes back undefined as if it doesn't see the parent provider. I think I'm ether doing something wrong initializing the context myself or for some reason the two components I'm importing just don't share the same context. Please help!! Not sure if I should give up on this and just use redux.

Maybe you are making multiple instances of the component providing the context. Let's say you have a component Sound, which starts by:
const { Provider, Consumer } = React.createContext();
If you import this library from your main project, the context will be created at the global space. You then use it to render your document tree. But in another component you also imported this library, which had to be resolved during webpack transpilation. It thus has its own copy of the above lines and a context object created in its own space. The problem occurs when you try to use the Consumer, because the Provider was only made by the main project for the first context object, and the second context's provider instance was never instantiated, thus returns undefined.
A solution to the problem is to enforce a single context object, which you can achieve by telling the second component's webpack that the provider-owning library is an external, so when webpack reaches e.g. the "import sound" line, it will not go further and will assume this dependency is resolved at runtime. When runtime comes, it will take it from the same place where the main project is taking it. To do this in webpack, e.g. for above "sound" library, add this to your other component (not main project):
{
...
externals: {
...
'sound': 'sound'
}
...
}
Also in your component package.json:
{
...
peerDependencies: {
"sound": "^1.2.3"
}
}

Apart from Darko's answer, esm and cjs export is also a possible reason for context to fail in a package. If you use the hook in esm and the provider in cjs, you will not get the value for that context.

I recently had a similar issue where I was trying to consume the value of a context inside my library components but using the provider (imported from the package) in the host app.
I managed to solve the issue just by making react and react-dom external and peerDependencies when bundling in rollup.

should your code of consumer be
<React.Fragment>
<MyContext.Consumer>
{value => /* render something based on the context value */}
</MyContext.Consumer>
</React.Fragment>
as stated from the official react doc : https://zh-hant.reactjs.org/docs/context.html
when you define
you can use it like

ReactJS - Accessing data on Different Pages

I am trying to access data gathered from a user on one page and use it on another page. I have tried following these articles:
https://travishorn.com/passing-data-between-classes-components-in-react-4f8fea489f80
https://medium.com/#ruthmpardee/passing-data-between-react-components-103ad82ebd17
https://codeburst.io/react-js-pass-data-from-components-8965d7892ca2
I have not been able to get it to work. this.props.{variableName}keeps returning as undefined. My code is as follows.
The following is the Home Page:
import React, { Component } from 'react';
import {Button} from 'reactstrap';
import { browserHistory } from 'react-router';
class HomeScreen extends Component {
constructor(props) {
super(props);
this.state = {
working: "",
};
}
WorkReqNav(){
this.setState=({working: "WORKING"});
browserHistory.push("/WorkReq");
}
render() {
return (
<div>
<Button size="lg" onClick={this.WorkReqNav.bind(this)} type='button'>HIT IT!</Button>
</div>
);
}
}
export default HomeScreen;
The following is the workReq screen:
import React, { Component } from 'react';
import {Button} from 'reactstrap';
class WorkReq extends Component {
constructor(props) {
super(props);
}
workCheck(){
var working = this.props.working;
alert(working);
}
render() {
return (
<div>
<Button size="lg" onClick={this.workCheck.bind(this)} type='button'>HIT IT!</Button>
</div>
);
}
}
export default WorkReq;
If you need anything more, please let me know. i am really new to React and this is my first time attempting anything like this.

welcome to the React world. I bet you'll love it when you gradually get familiar with cool stuff that you can do with React. Just be patient and keep practicing.
So the first suggestion I would make is that, like any other javascript environment, React also evolves very quickly. So although basic principles are the same, when you follow a new article on one hand, on the other hand you can check if the libraries or methodologies that are demonstrated are up to date.
Fasten your belts and let's do a quick review based on your question and libraries that I see you used in your example.
In terms of router, I see that you directly export things from react-router
When we check the npm page (https://www.npmjs.com/package/react-router) of react-router they make the following suggestion
If you are writing an application that will run in the browser, you
should instead install react-router-dom
Which is the following package https://www.npmjs.com/package/react-router-dom
You can get more details and find more tutorials in order to improve your skills by checking their official page https://reacttraining.com/react-router/web/guides/philosophy
Let's take a look at the code snippet sasha romanov provided that's based on react-router-dom syntax
with react-router-dom when you define a route with following syntax
<Route path="/" component={HomePage} exact />
react-router-dom automatically passes match, location, and history props to HomePage component. So when you console.log() these props, you should be able to display somethings on your console. And once you have access to history props, instead of browserHistory, you can use this.props.history.push("/some-route") for redirections.
Let's take a look at the part related to withRouter. In the example above, we could use history because HomePage component was passed directly to the Router component that we extract from react-router-dom. However, in real life, there might be cases in which you want to use history props in a component that's not passed to the Router but let's say just a reusable button component. For these cases, react-router-dom provides a Higher Order Component called withRouter
A Higher Order Component is (from React's official documentation)
https://reactjs.org/docs/higher-order-components.html
Concretely, a higher-order component is a function that takes a
component and returns a new component.
So basically, whenever you wrap any component with withRouter such as export default withRouter(MyWrappedReusableComponent), in your reusable component, you will have access to the props history, location, pathname
That said, my first impression regarding to your problem does not seem to be related to router logic but rather exchanging data between components.
In your original question, you mentioned that
I am trying to access data gathered from a user on one page and use it on another page
There are a couple of cases/ways to approach this issue
1) If these two components are completely irrelevant, you can use state management system such as Redux, mobx or you can use React's context API https://reactjs.org/docs/context.html. HOWEVER, since you are new to React, I would suggest not tackle with these right know till you are comfortable with the basic flow. Because at some point trying to implement a flow with a lot of libraries etc. is quite overwhelming. Believe me, I tried when I was also new to React and I was really close to break my computer after opening my 100th browser tab to look for another method from another library
2) You can implement a simple parent-child relationship to pass data between components. Let me explain what I mean by using references from your code snippet.
I believe you want to update working which is a state in your HomeScreen and you want to pass and use this updated value in your WorkReq component.
If we ignore all the routing logic and decide to go without routes, what you need to do is the following
import React, { Component } from 'react';
import {Button} from 'reactstrap';
import { browserHistory } from 'react-router';
import WorkReqComponent from 'path/to/WorkReqDirectory';
class HomeScreen extends Component {
constructor(props) {
super(props);
this.state = {
working: "WORKING",
};
}
render() {
return (
<div>
<WorkReqComponent working={this.state.working} />
</div>
);
}
}
By this way, when you log this.props.working; in your WorkReqComponent you should be able to display the data that you passed. You can refer to this as passing data from parent to child.
I checked the articles you listed. They also seem to explain data transfer between parent to child, child to parent or between siblings.
In your case, what you really need to implement can be categorized as between siblings
I prepared a sample for you with react-router-dom to demonstrate one possible structure which might yield your expected outcome.
https://codesandbox.io/s/ojp2y0xxo6
In this example, the state is defined inside of the parent component called App. Also state update logic is also defined inside of the parent component. HomeScreen and WorkReq components are the children of App thus they are siblings. So, in order to transfer data between siblings, one of them was given the task of updating parent's state via passing state update logic to this component. The other one has the task of displaying parent's state's value.
At this point, since you are new and in order not to overwhelm yourself, you can experiment with parent-child-sibling data transfer topic. Once you are getting comfortable with the implementation and the logic, you can gradually start taking a look at React's context api and Redux/mobx.
Let me know if you have any questions regarding to the sample I provided

You can use react-router-dom lib and from seeing your code i think in parent component (app.js) you defined route for each child component you'd like to access
like this example here:
import { BrowserRouter, Route, Switch } from 'react-router-dom';
<BrowserRouter>
<div>
<Switch>
<Route path="/" component={HomePage} exact />
<Route path="/homescreen" component={HomeScreen} />
<Route path="/workreq" render={(props) => <WorkReq {...props} />} /> // here you can pass the props by calling render
<Route component={NoMatch} />
</Switch>
</div>
</BrowserRouter>
and then if you want to change route you can just call this.props.history.push('/workreq')
and if you didn't include route for the component in <BrowserRouter />
in the component that it's not included you can import withRouter and export like this withRouter(HomeScreen) and now you can access router props
if this isn't the answer you are looking please inform me to update my answer, i hope this can help

React native: export default App with multiple module wraps

I Have the following App.js in my react native project:
class App extends Component {
render() {
return (
<ApolloProvider store={store} client={client}>
<AppWithNavigationState />
</ApolloProvider>
);
}
}
export default App = codePush(App);
I am trying to add aws amplify authenticator to my project (https://github.com/aws/aws-amplify/blob/master/media/quick_start.md#react-native-development) but the steps tell me to add :
export default withAuthenticator(App);
^^ How do I do that when I have already codePush wrapped around the App component that I am exporting?

TL;DR:
The withAuthenticator is basically a higher order component which takes a component, decorates it (i.e. provide some special props or customizations of sorts) and returns a new component composed of the component you passed in. So in your case if you want multiple HOCs, you can simply say -
export default withAuthenticator(codePush(App))
This syntax can get potentially nasty from a readability standpoint if you have, say, 5 decorators. It is useful in such cases to use the new decorator syntax. With it you can do neat things like -
#mySpecialDecoratorThatDoesNiceThings
#withAuthenticator
#codePush
export default class App extends Component {
...
}
If you are using babel, check out this transform-decorators babel plugin to make sure decorators are correctly transpiled.

Why HOC are applied during exporting of component in place of importing it

My basic understading is that HOC like connect (for connecting with redux store) and other HOC's are applied to a component while exporting it.
Like this
import React, { Component } from 'react';
import './App.css';
import myHoc from './myHoc/index';
class App extends Component {
render() {
return (
<div className="App">
</div>);
}
}
export default myHoc({})(App);
Where as a better thing would be to apply HOC during import as it would make it easier to make reusable component. The same component can pick up props from store or from props and that would be the responsibility of the parent component to check what to give which HOC to apply on the component.
I know we can use container components which takes the component and render children but that just adds code in the JSX (wont look good if there are many container components)
though we can do it like this
import React, { Component } from 'react';
import './App.css';
import myHoc from './myHoc/index';
import AppChild from './AppChild';
const NewAppChild = myHoc({}, ()=> {
})(AppChild);
class App extends Component {
state = {
count: 1,
};
reRender = () => {
this.setState({count: this.state.count + 1});
};
render() {
return (
<div className="App">
<NewAppChild handleClick={this.reRender} count={this.state.count}/>
</div>
);
}
}
export default App;
What my question is that, is there something better that can handle this kind of situations where I want to apply my HOC on import that is each many container components can import it and they can apply different HOCs depending on the needs.

There is no single concrete reason for this design choice - as you have already seen you can invoke your HOC wherever you use the component - but I see at least 1 advantage: configuration & component reuse.
In your example, myHoc takes no parameters or configuration so this doesn't necessarily apply, but imagine instead that you are invoking connect from redux.
In most use cases, connect accepts 2 configuration functions -
mapStateToProps & mapDispatchToProps - that define the behaviour. If you define those within MyComponent then any consuming component can import MyComponent from 'MyComponent' and start using it.
If you instead rely on the parent component to call connect() then you are forcing every consumer to re-implement the configuration of connect as well. That may mean many instances of duplicated configuration and adds to the complexity for consuming components.
That being said, there are certainly cases where you might want this behaviour - for example, if you wanted to connect the same component to different state definitions. Ultimately you need to pick the best pattern to support what you need from the component.