Redux on functional components in Reactjs (web) - javascript

I am writing this question cause I would like to ask you for some help in how to use the redux on my functional components. I had a look at other examples with React components but I cannot understand how to get the "store" value in functional components.
My idea is to use my
store.getState()
To check states and interact with the UI, inside my functional component but I cannot make it happen.
Any help please ?
For example, a functional component :
import React from 'react';
import withStyles from 'isomorphic-style-loader/lib/withStyles';
import s from './Header.css';
import { Navbar, Nav } from 'react-bootstrap';
import HeaderMenu from '../HeaderMenu';
import cx from 'classnames';
function Header() {
return (
<Navbar fluid fixedTop id="Header" className={s.navContainer}>
<Nav block className={cx(s.HeaderTitle, s.hideOnSmall)}>Project title</Nav>
<HeaderMenu />
</Navbar>
);
}
export default withStyles(s)(Header);
How can I use the "store" object inside my Header component ? It works on my App component, just I don't know how to use it within my components.
My questions are:
Should I use actions for retrieving the state instead ??
Should I pass the store object component to the component properties?
Thanks in advance!
EDIT :
I am using https://github.com/kriasoft/react-starter-kit
with the redux branch https://github.com/kriasoft/react-starter-kit/tree/feature/redux

As of version 7.x react-redux now has hooks for functional components.
Header.jsx
import React from 'react';
import withStyles from 'isomorphic-style-loader/lib/withStyles';
import s from './Header.css';
import { Navbar, Nav } from 'react-bootstrap';
import HeaderMenu from '../HeaderMenu';
import cx from 'classnames';
import { useSelector } from 'react-redux'
function Header() {
const store = useSelector(store => store)
return (
<Navbar fluid fixedTop id="Header" className={s.navContainer}>
<Nav block className={cx(s.HeaderTitle, s.hideOnSmall)}>Project title</Nav>
<HeaderMenu />
</Navbar>
);
}
export default withStyles(s)(Header);
index.js
import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
import App from './App';
import { Provider } from 'react-redux'
import store from './store'
ReactDOM.render(
<Provider store={store}>
<App />
</Provider>,
document.getElementById('root')
);

As Dan Abramov mentioned in his insanely famous Egghead.io series, presentational component shouldn't be aware of Redux store and shouldn't use it directly. You should create something called container component, which will pass necessary state fields + action callbacks to your presentational component via properties.
I highly recommend to watch Dan Abramov's Egghead.io series if above concepts are not familiar to you. Patterns he is describing there are de facto standard style guide for writing React+Redux applications nowadays.

If you want to get the Redux state on a functional component, you either have to manually connect the component and Redux, which is very tedious. You would have to access the reducer variable inside your React Component, meaning import the reducer into the component file among other configurations.
This would interfere with other benefits you would normally get, such as action creators, dispatching actions automatically through middleware, and more.
A cleaner idea is to just use the Provider Component that comes with React-Redux to turn your Header component into a Container. A Container is a react component that 'listens for' any changes that have been made to the store. You are essentially wrapping your Header component in a higher order component that is connected directly to the redux store.
This way is more scalable and you can easily create a boilerplate file that can be used with any React/Redux project.

Try to understand the individual modules/components a boilerplate project contains before going with it. If you are new to react (and its complementary libraries) I recommend you start here:
https://github.com/petehunt/react-howto
For redux:
http://redux.js.org/
These are both great ressources which clarify the majority of react related questions on stackoverflow.

You can use react-redux library, and using connect you will access your store data as a component props - it's easy and efficient.

Related

Component Palette Custom Hook

I am fairly new to React and still wrapping my head around custom-hooks. I cam across a code where a custom hook was created to handle the component imports.
useComponentPalette.js
import {TodoEditor} from './components/TodoEditor'
import {TodoItem} from './components/TodoItem'
import {TodoList} from './components/TodoList'
import {CheckBox} from './components/CheckBox'
const defaultComponents = {
TodoEditor,
TodoItem,
TodoList,
CheckBox
}
export function useComponentPalette(){
return defaultComponents
}
And then in order to use the hook,
const {TodoItem, TodoList, Checkbox } = useComponentPalette()
My Question :- Does this approach provides any advantage over the regular imports in the component ? or this is an anti-pattern ?
How I usually import the components is as follows
import {TodoEditor} from './components/TodoEditor'
import {TodoItem} from './components/TodoItem'
import {TodoList} from './components/TodoList'
import {CheckBox} from './components/CheckBox'
function App(){
return(
<>
<TodoList/>
</>
)
}
It's not a good idea to use react hooks like this you can get the same result without react hook
// first file name.js
import {TodoEditor} from './components/TodoEditor'
import {TodoItem} from './components/TodoItem'
import {TodoList} from './components/TodoList'
import {CheckBox} from './components/CheckBox'
export default {
TodoEditor,
TodoItem,
TodoList,
CheckBox
}
//component file
import * as Component form 'first file name';
//<Component.TodoEditor/>
//or
import {TodoEditor} form 'first file name';
The way that I use react-hooks is for making my code more dry and increase it's readability, so react-hooks is not good fit for this kind of usage.
Hi #Sachin,
In my option, React JS use hook to manage reuse stateful logic between components. In other word, Hooks do well to encapsulating state and share logic. If you want to do some stateful logic or condition base logic with these components, then it's fine with that. But if you are using just without condition in the given components. Then, This Is useless for making the custom hook. You can do that without a custom hook in a simpler way.
Here is a simple way to do that:-
In components folder. I create index file, this is the entry point of all my exporting components
In that file. I export all my components, as you can see.
I use that components like this. It much better way. In my option.
import { Header, Footer, Sider } from "./components"
before using react custom hooks, we should be aware of the rationale behind it.
Customs hooks functionality was provided to reuse stateful logic. If logic doesn't require any state, we will use simple functions and if it is about components only there there are different patterns for making code general and scaleable.
So, there is no usage of custom hook in above case at all. For me, I would go with the following code for above scenario:
// components/index.tsx
import {Todo} from './todo'
import {CheckBox} from './components/CheckBox'
export {
Todo,
CheckBox
}
// componentns/todo/index.tsx
import {Editor} from './Editor'
import {Item} from './Item'
import {List} from './List'
const Todo = {
Editor,
Item,
List
}
export default Todo;
and usage will be like
import { Checkbox, Todo } from "components"
...
<Checkbox ... />
<Todo.List ...>
<Todo.Item ... >
</Todo.Editor ... />
</Todo.Item ... >
</Todo.List>
...
P.S Usage can be different based upon the logic of components, just giving an hint how we can patterns to serve our purpose.
Hope it helps.

How to test how many times a component was rendered in React?

I have a scenario with 2 components:
App
People
I want to test if People gets rendered 10 times inside App. So, I'm trying to test that using Jest. So far, I did this on my src/App.test.js:
import React, { Component } from "react";
import People from "./components/People";
import App from './App';
test('Total people = 10', () => {
expect(App).find(People).toHaveLength(10);
});
But I get a message saying:
TypeError: expect(...).find is not a function.
How can I test how many times a component gets rendered inside another component using React and Jest? Can anyone help me?
For testing react components first you need to render them, there are some tools for doing that, but since your reasoning in this test is to check how many times a component has been rendered inside another component, enzyme does a good job with its shallow method.
import React from "react";
import App from "./App";
import People from "./components/People";
import { shallow } from "enzyme";
it("Total people = 10", () => {
const wrapper = shallow(<App />);
expect(wrapper.find(People)).toHaveLength(10);
});
You'll need to set up enzyme in your project first, read the docs for more details.
The current trend in testing is to check for the things the user actually sees in the page, so most people is using react-testing-library, It'll be good for you to check it out
If you ever switch to react-testing-library, you might write the test something like this:
import React, { Component } from "react";
import App from './App';
import {render} from "#testing-library/react";
test('Total people = 10', async () => {
const { getAllByText } = await render(<App />);
expect(getAllByText('string_in_People')).toHaveLength(10);
});
Basically you'd use one of the library's built-in getAllBy... query methods to query for all instances of an element that appears exactly once in each instance of your <People /> component. The resulting set's length will equal the number of <People /> instances on the page.

React component render called twice without changing state

I am rendering a simple react component, where no state and props are set
I am logging text to console only once inside the render function but it's logged twice:
rendering counter
rendering counter
Below is the code of the component counter.js
import React, { Component } from "react";
class Counter extends Component {
render() {
console.log("rendering counter"); //this is printed two times
return <span className={"badge m-3 badge-primary"}>counter</span>;
}
}
export default Counter;
And index.js
import React from "react";
import ReactDOM from "react-dom";
import "./index.css";
import * as serviceWorker from "./serviceWorker";
import "bootstrap/dist/css/bootstrap.css";
import Counter from "./components/counter";
ReactDOM.render(
<React.StrictMode>
<Counter />
</React.StrictMode>,
document.getElementById("root")
);
serviceWorker.unregister();
it seems that the render function in the component is called two times. But why is that?
As it was written in docs:
Strict mode can’t automatically detect side effects for you, but it can help you spot them by making them a little more deterministic. This is done by intentionally double-invoking the following methods:
Class component constructor method
The render method
setState updater functions (the first argument)
The static getDerivedStateFromProps lifecycle
The shouldComponentUpdate method

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!!!

Refresh contentComponent in react-navigation

I am using React-Navigation where I am using functionality of custom drawer by using contentComponent of React-Navigation.
const DrawerNavigation = DrawerNavigator({
DrawerStack: { screen: DrawerStack }
}, {
contentComponent: DrawerComponent,
drawerWidth: 300
})
Here DrawerComponent is my custom navigation drawer where I have used custom navigation items like username, profile picture, email address and other menus.
Now whenever user updates their profile I want to refresh my DrawerComponent, I am not able to find any way to do it. Can anybody suggest me a good way to implement this?
Couple of options here, and all are tight to how you want to achieve your state management.
First, one solution would be to have the your user state in the component creating the DrawerNavigator, and pass it down to your custom drawer component. This presents the disadvantage of having to recreate your navigator on state change and create a blink. I do not advice to use this solution but it's worth mentioning as a possibility.
You could also use a React Context, have your user state in a top level component, create a provider passing it the user as the value and make your drawer a consumer of this context. This way, every time the user changes your drawer component would re-render.
What I use personally is Redux to connect my Drawer directly to my global state. It involves a bit of setup but it's worth it in the end. A root component could look like this:
import React from 'react'
import { Provider } from 'react-redux'
export default () => (
<Provider store={store}>
<App />
</Provider>
)
Where store is the result of:
import { createStore, combineReducers } from 'redux'
import reducers from './reducers'
const store = createStore(combineReducers(reducers))
Your reducers are going to be the state of your app, and one would be dedicated to your user data.
Then your Drawer component could be:
import React, { Component } from 'react'
import { View, Text } from 'react-native'
import { connect } from 'react-redux'
#connect(({ user }) => ({ user }))
class Drawer extends Component {
render () {
const { user } = this.props
return (
<View>
<Text>My name is {user.name}</Text>
</View>
)
}
}
export default Drawer
Now, every time you change your user reducer, this Drawer component will re-render.
There is a few things your should know about Redux, so you should probably read up a bit the Getting Started docs.
I know it is a old question now but you can do this by importing the code like
import DrawerView from '../Drawer/Drawer'
contentComponent: DrawerView
then in the DrawerView file
class DrawerView extends Component {
render(){
return(
//Do your stuff here
)
}
}
export default DrawerView;
for more info please visit this link and thank to Kakul Gupta for this https://codeburst.io/custom-drawer-using-react-navigation-80abbab489f7
The easiest way to change menus without using redux is, using createSwitchNavigator.
https://reactnavigation.org/docs/en/auth-flow.html

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