We Keep Coding

Use Redux module inside react component

I have a module A built in react-redux. A is the parent component name which looks somewhat like
const app = (
<Provider store={store}>
<A />
</Provider>
);
ReactDOM.render(app, document.getElementById('id'));
Inside component A there is a component C.js which has a connect function
A.js
render() {
return (
<div>
<C />
</div>
);
}
C.js
render() {
return(<div>SomeCode</div>
}
export default connect(mapStateToProps, mapDispatchToProps)(C);
There is another B.js file which is a ReactComponent (no redux used here). It has its own state.
I want to use the component A inside B's render method something like
import A from '/path'
render() {
return (<A/>)
}
While doing so I am getting an error.
Could not find "store" in the context of "Connect(C)".
Either wrap the root component in a , or pass a custom React context provider to
and the corresponding React context consumer to Connect(C) in connect options.
Any help appreciated.

I modified parent and exported it as following
render(){
return(
<Provider store={store}>
<A />
</Provider>
);}
Importing A worked fine

React/Router/MemoryRouter - how to pass history property and use push() in child component?

I'm building a React app where I do NOT want the URL in the browser to be updated. I am NOT using 'react-router-dom' but only 'react-router' and MemoryRouter (https://reacttraining.com/react-router/web/api/MemoryRouter). The history.push() is available directly in the component statements but I wish to pass the history to children of children of these main components but the property is undefined.
Here is the Router section in main App.js (components Home and ScreeningTool can access this.props.history.push() as expected):
...
import {Route, MemoryRouter} from "react-router";
...
<MemoryRouter>
<Route exact path="/" component={Home} />
<Route path="/screening-tool" component={ScreeningTool} />
</MemoryRouter>
...
Both Home and ScreeningTool both use child component AppLink that generates a 'link' to navigate between Home and ScreeningTool like so (notice I'm passing 'history' as a prop):
Home.js:
...
<AppLink
url="/"
label="Screening Tool"
history={this.props.history}
/>
...
AppLink.js:
...
<div className="pseudo-link">
<span onClick={() => this.props.history.push(this.props.url)}>
{this.props.label}
</span>
</div>
...
The above code works. But there are children components in Home that will create their own AppLinks and also greatgrandchildren. I do NOT want to pass the history property as a component prop from Parent to Child to GrandChild components because this does not seem efficient. I have found the following stackoverflow questions but none of these options are working for me:
this.props.history.push works in some components and not others
react-router getting this.props.location in child components
I tried the newer 'userHistory' as described in the second URL above:
...
import { useHistory } from 'react-router';
...
render() {
let history = useHistory();
return (
<div className="pseudo-link">
<span onClick={() => history.push(this.props.url)}>
{this.props.label}
</span>
</div>
);
}
...
but I get Error: Invalid hook call. Hooks can only be called inside of the body of a function component..
I tried using withRouter as defined here https://reacttraining.com/react-router/web/api/withRouter but I get Error: Invariant failed: You should not use <withRouter(PseudoLink) /> outside a <Router>.
Finally, the accepted answer for this.props.history.push works in some components and not others ends with block of code export default withRouter(connect(mapStateToProps, matchDispatchToProps)(ChildView)); but does not explain where mapStateToProps or matchDispatchToProps comes from?
I'm thinking the issue is that I am using MemoryRouter and not normal/most common Router from 'reacto-router-dom'.
Can anyone help me out?

useHistory is a Hook so it should be used in a functional component, not inside a class based component.
Finally, the accepted answer for this.props.history.push works in some components and not others ends with block of code export default withRouter(connect(mapStateToProps, matchDispatchToProps)(ChildView)); but does not explain where mapStateToProps or matchDispatchToProps comes from?
-If you're not using redux then you can just use
export default withRouter(yourComponentName);
update
I've changed the AppLink component to this and it is working fine
import React from "react";
import "./AppLink.css";
import { useHistory } from 'react-router';
const AppLink = props => {
const history = useHistory();
return (
<div
className="app-link-button"
onClick={() => history.push(props.url)}
>
<span>{props.label}</span>
</div>
);
};
export default AppLink;

Is Fetching Data in App.js file allowed in React App?

I have built authorization into my React App using passport.js, and I would like to, in my App.js file, fetch my authorization routes to see if a user is logged into the app, or if nobody is logged in.
To help with the question, I have shared a condensed version of my React App's App.js file, and Index.js file.
// App.js File
// Import React Libraries, Routes, Container Pages
import React, { Component } from 'react';
import { connect } from 'react-redux';
import { Route } from 'react-router-dom';
import { userActions } from './actions/auth/auth-actions.js';
import GameLanding from './containers/StatsPages/Game/GameLanding';
import AppFooter from './components/AppFooter';
// And Create The App
class App extends Component {
constructor(props, context) {
super(props, context);
}
componentDidMount() {
this.props.dispatch(userActions.authorize());
}
render() {
return (
<div>
<Route exact path='/stats/games' render={() => <GameLanding userInfo={this.props.userInfo} />} />
<AppFooter />
</div>
);
}
}
// export default App;
function mapStateToProps(reduxState) {
return {
userInfo: reduxState.authorizedReducer.userInfo,
authorized: reduxState.authorizedReducer.authorized,
loading: reduxState.authorizedReducer.loading
};
}
export default connect(mapStateToProps)(App);
... my entire App.js file has ~15 Routes components, and (part of) my goal with my App.js file is to fetch the authorized and userInfo props, and pass these to the components in the various routes. I showed an example where I pass the userInfo prop to the GameLanding component.
Here is how I have set up my Index.js file.
// Index.js
// Import Libraries
import React from 'react';
import ReactDOM from 'react-dom';
import { Provider } from 'react-redux';
import { BrowserRouter } from 'react-router-dom';
// Import CSS and the App
import App from './App';
import 'react-table/react-table.css';
import './index.css';
import './App.css';
ReactDOM.render(
<Provider store={store}>
<BrowserRouter>
<App />
</BrowserRouter>
</Provider>,
document.getElementById('root'));
My current problem is as such: For some reason, fetching the userInfo and authorized props is breaking my app. I am unfortunately getting no error messages... rather, all of the react-router-dom Links in my app are simply not working... clicking them changes the url, but the pages of my app no longer change...
My questions are then, (a) am i allowed to fetch authorization data in App.js in the manner I am doing so (using connect, with mapStateToProps, etc.), or am I doing this all wrong?
Whether or not somebody is logged into my app is an app-wide thing, not a page-specific thing, and I figured for this reason (also to prevent having to fetch auth props in many many container pages) that App.js is the best place to grab these props.
Any thoughts on why my app is breaking, or how else my App.js file should look (I am ~99% sure my index.js is fine), would be greatly appreciated! Thanks!
Edit: For reference, doing the following: (i) importing userActions, (ii) calling userActions.authorize() in componentDidMount, (iii) including the mapStateToProps and connect on bottom of app, etc. works for loading the auth props in any of my container components. e.g. if i had this code in my GameLanding component, it doesnt break the react-router-dom Links app-wide in the same manner that it does when this code is in App.js. Hence the title of the question. Thanks!

1) Reason for app breaking:
I am assuming userInfo and authorized props will be undefined, as component renders initially before componentDidMount runs and you have not handled undefined props. You could also pass default props for these props.
2) Better structure for authorization
I am assuming you need to authenticate each route for authorization.
i) Create routes file and enter all routes for your app.
ii) <Route exact path='/stats/games' component={GameLanding} onEnter={reqAuth}/>
Inside reqAuth function you should check if the user is authorized for that route or not.
iii) Inside App component call action for fetching data, store in store and use GameLanding as child component and pass props only when they are defined.
That is not whole code, but should give you gist.
Happy Coding!!!

What is the right way to use new React hook useContext?

I have some difficulties to understand the new way to use react Context API.
I have an app with a custom class Firebase. Now I want to make a hook to pass it. Before I used HOC (higher-order Component) and context.
My questions
Do I need to use HOC or it's a new way to do this?
Do I need the Context.Provider or it's new Hook?
Do I need to declare default value as a null or I can pass my Object
right from context.js
How can I use a new Hook instead of HOC in mine code?
Here is my code with some comments related to questions
// context.js this is my hoc
// index.jsx
import App from './App'
import Firebase, { FirebaseContext } from './components/Firebase'
const FirebaseContext = React.createContext(null)
export const withFirebase = Component => (props) => {
// I don't need to wrap it to the FirebaseContext.Consumer
// 1 But do I need this HOC or it's a new way?
const firebase = useContext(FirebaseContext)
return <Component {...props} firebase={firebase} />
}
ReactDOM.render(
// 2 Here I'm lost. Do I need the FirebaseContext.Provider or not?
// 3 Do I need to declare value her or I should do it in context.js as a default?
<FirebaseContext.Provider value={new Firebase()}>
<App />
</FirebaseContext.Provider>,
document.getElementById('root'),
)
// App.jsx
// 4 Can I use a new Hook instead of HOC here and how?
import { withFirebase } from './components/Firebase/context'
const App = () => {
const firebase = this.props.firebase // But should be useContext(FirebaseContext) or something like this?
return(...)
}
export default withFirebase(App) // I don't need this with the Hook
Any help appreciated.

You should understand it first that, useContext is just to make use of Context and acts like a consumer and not Provider.
To answer your questions
Do I need to use HOC or it's a new way to do this?
You don't need an HOC with hooks. Hooks are meant to replace HOCs and render props pattern.
Do I need the Context.Provider or it's new Hook?
There is no hooks equivalent of Context.Provider. You have to use it as is.
Do I need to declare default value as a null or I can pass my Object
right from context.js
The default value to createContext is only used if you don't pass a value props to the Context.Provider. If you pass it the default value is ignored.
How can I use a new Hook instead of HOC in mine code?
Instead of using useContext in the component returned by HOC use it directly within the component
Sample code
/ context.js this is my hoc
// index.jsx
import App from './App'
import Firebase, { FirebaseContext } from './components/Firebase'
const FirebaseContext = React.createContext(null)
ReactDOM.render(
<FirebaseContext.Provider value={new Firebase()}>
<App />
</FirebaseContext.Provider>,
document.getElementById('root'),
)
App.jsx
const App = () => {
const firebase = useContext(FirebaseContext)
return(...)
}
export default App;

Do I need to use HOC or it's a new way to do this?
No, you don't need to use HOC as best technique.
Why?
Starting from React v7.0, you can use functional-based components.
From this version efficient is to use the the latest
technique named HOOKS, which were designed to replace class and
provide another great alternative to compose behavior into your
components.
Do I need the Context.Provider or it's new Hook?
Hook like useContext() has a relation with Context.Provider.
Context is designed to share data that can be considered “global”.
The Provider component accepts a
value prop to be passed. Every Context come with a Provider.
Context.Provider component available on the context instance is used to provide the context to its child components, no matter how deep they are.
Do I need to declare default value as a null or I can pass my Object right from context.js?
No, you don't need necessarily to declare a default value.
Example of defining the context in one corner of the codebase without defaultValue.
const CountStateContext = React.createContext() // <-- define the context without defaultValue
How can I use a new Hook instead of HOC in mine code?
index.jsx
import App from './App'
import Firebase, { FirebaseContext } from './components/Firebase'
const FirebaseContext = React.createContext(null)
ReactDOM.render(
<FirebaseContext.Provider value={new Firebase()}>
<App />
</FirebaseContext.Provider>,
document.getElementById('root'),
)
Root Component: App.js, where will be used data comes form context:
const App = () => {
const firebase = useContext(FirebaseContext)
return(...)
}
export default App;

How to test a component with a nested container with React and Redux?

Due to the complexity of the application I am working on I have decided on using a nested redux container rather than passing an action as a prop down to the child components. However, this has proved to be problematic for unit testing when rendering the OuterContainer with jsdom in combination with mocha, chai and sinon.
Here is a contrived example of the view structure:
<OuterContainer>
<div>
<InnerContainer />
</div>
</OuterContainer>
where OuterContainer & InnerContainer are wrapped with connect. e.g.:
export connect(<mapStateToProps>)(<Component>)
When running tests the error I am getting is:
Invariant Violation: Could not find "store" in either the context or props of "Connect(Component)". Either wrap the root component in a `<Provider>`, or explicitly pass "store" as a prop to "Connect(Component)".
Is there a way to unwrap or stub the InnerContainer for unit testing without having to use shallow rendering?

Wrap your component in <Provider> when testing. It’s up to you whether to supply a real store or a mock with { dispatch, getState, subscribe } to it. Wrapping the outermost component in <Provider store={store}> will also make the store available to the child components at any level of nesting—just like in the app itself.
const store = createStore(reducer) // can also be a mock
ReactTestUtils.renderIntoDocument(
<Provider store={store}>
<OuterContainer />
</Provider>
)

Another approach is to export both the component to be connected and the container. The container as default, of course.
export const Comp = (props) => (<p>Whatever</p>)
export default connect(...)(Comp)
Hence, you can unit test Comp.

Not sure if this is what your problem is, but I'm sure this will probably help a few people out there looking at this feed.
I had the same error and it was a simple fix:
I had forgotten to pass my component my store object in my entry file (using webpack).
I just added an attribute to the Root component "store={store}" see below:
document.addEventListener("DOMContentLoaded", () => {
const store = configureStore();
ReactDOM.render(<Root store={store} />,
document.getElementById('content'));
});
This was my root file code for reference as well:
import React from 'react';
import { Provider } from 'react-redux';
import App from './app';
const Root = ({ store }) => (
<Provider store={ store }>
<App />
</Provider>
);
export default Root;
Hope that helps someone!

Mock the Provider component to return the child component.
Add this before describe().
jest.mock('Provider', () => ({children}) => children);