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
Related
This comes up often, but no solution appears to work and I feel like I've exhausted every option I can think of, so I'm turning to here, believing this may be a slightly different scenario and not a duplicate. If there's an existing solution that works, I'm happy to be shown otherwise.
In my last create-react-app project, I had no problem rendering new pages with Router and useHistory. Using the exact same set up, I've run into the issue where history.push(url) changes the url in the address bar but the page doesn't re-render.
I'm using:
React v17.0.2
react-router-dom v5.3.0
history v5.0.1 (also attempted
on v4.10.1)
App.js
import React from 'react';
import { BrowserRouter as Router, Route, Switch } from "react-router-dom";
import { Page } from './stories/Page';
import './App.css';
function App() {
return (
<Router>
<Switch>
<Route exact path="/">
<Page homepage={true} />
</Route>
<Route path="/project/([a-zA-Z0-9]+)/([a-z\-0-9]+)/([a-z\-0-9]+)/" render={urlprops =>
<Page projectID={urlprops.match.params[0]} homepage={false} />
} />
<Route path="/project/([a-zA-Z0-9]+)/([a-z\-0-9]+)/" render={urlprops =>
<Page projectID={urlprops.match.params[0]} homepage={false} />
} />
</Switch>
</Router>
);
}
export default App;
component-page.js
import React, { useEffect, useState, useCallback } from 'react';
import PropTypes from 'prop-types';
import { useHistory } from 'react-router-dom';
import './menuitem.css';
export const Component = ({ url, ...props }) => {
let history = useHistory();
function handleItemClick(e) {
history.push(url); // <- calls fine, tested with logging to console
}
...
I've seen older solutions suggest passing history props through Router but in my last app I was able to use the set up above, and any level nested subcomponent would be able to call the useHistory hook and use push if they were set up like component-page.js above. Therefore I haven't shown the components between App.js and component-page.js on the belief that this should be irrelevant to useHistory functioning correctly.
Possibly relevant:
If I enter the URLS in the address bar and hit return, Router renders the correct components, suggesting Router and Switch work fine with a freshly loaded page.
I have React dev tools set up to blink on
components when they re-render. After history.push(url) is called all
components blink, though none re-render (visually, at least).
Downgrading history to 4.10.1 seemed to fix a lot
of the recent reports of this issue for others. I had no such luck. Apparently there was/is a bug with react-router-dom v5+ which meant history.push was not working with history v5+.
I also placed a simple button component in the Page component that fired a request to history.push("string url here") with the same issue. It calls, address bar changes, page doesn't re-render. In my mind, this rules out it being some sort of nesting issue, which I didn't believe it was anyway.
Update
Checking history in console after calling history.push('url string') shows the following under the location property. This looks like it's acting as intended (I'm only expecting pathname to match the url I tried to point to).
{
"pathname": "url string",
"search": "",
"hash": "",
"key": "ctks7v"
}
Update 2
Possible progress. In my Page component I am calling fetch in a hook to catch any update, like so:
useEffect(() => {
apiFetchProject(projectID);
}, []);
I'm now wondering if this is my problem? That this hook isn't seeing the url as a change that requires firing apiFetchProject(projectID). The reason I say this is that console calls confirm this hook isn't being called here after my history.push, but a console call to the Page component is happening. I've tried calling the hook with any change in props.location but this comes back as undefined each time, which means the hook isn't called.
Update 3
If, on Page, I use import { useLocation } from "react-router-dom"; with let location = useLocation(); and let a hook look for a change in location, Page now successfully calls fetch after a history.push call. But something doesn't seem right about having to do this too? I feel I would have seen it as a standard instruction.
I'm having to add it to every component to see re-rendering of anything. The fetch in Page is stored as a state and passed down as a prop to subcomponents. A change of this state should automatically re-render all subcomponents that are passed it, as happens when the page is loaded.
instead of the url, put the path ('/home')
I am trying to navigate to other page by using button click but it is throwing error by sayng that can not read property push of undefined.
I have did some research on history which is used forfunctional component.
How i can make use of history in class component or what is other way (react way) to navigate other page.
here is my code.
import React, { Component } from 'react';
class CentralBar extends Component {
constructor(props){
super(props)
this.state = {
}
this.someText = this.someText.bind(this);
}
someText(){
this.props.history.push(`/login/`);
}
render() {
return (
<div className="crentralPanel">
<button type="button" class="btn btn-light " onClick={this.someText}>Click on Text</button>
</div>
);
}
}
export default CentralBar;
history can be used in a class component. You just get access to it in a different way than in a function component.
In a function component, you would typically use the useHistory hook. But since hooks are exclusive to function components, you have to use a different method in a class.
Probably the simplest way is to use the withRouter higher order component. The only change you need to make is adding the import at the top, and wrapping the export.
import { withRouter } from 'react-router-dom';
export default withRouter(CentralBar);
This wrapper injects 3 props into the component: history, match, and location.
Note that the same rules apply to the HOC as do the useHistory hook since it's just another way of reading from the react-router context: the component must be a child of a Router provider component.
Please wrap your class component with withRouter.
import { withRouter} from 'react-router-dom';
export default withRouter(CentralBar);
If you didn't install react-router-dom module, please run this command to install this node module.
Please let me know if it works or not.
You can't use hooks in class components. You can find many solution in the Internet how to get it around, but I don't think it is worth it. If you really need use hooks in this component, make it with Functional Component. Class components should be used in react in small amount of cases. You can read about it here: React functional components vs classical components
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
I apologize if my phrasing is wrong in the title. I've recently gotten cookies going in my app. My Topnav component needs access to them, but I'm unsure how to get them there.
App.js -
import React, { Component } from 'react';
import { BrowserRouter as Router, Switch, Route, Link } from 'react-router-dom';
import Landing from './pages/Landing.js';
import LoginPage from './pages/LoginPage.js';
import Topnav from './pages/components/global/Topnav.js';
import './Global.css';
const App = props => (
<div>
<Topnav />
<Switch>
<Route exact path='/' component={Landing} />
<Route exact path='/login' component={LoginPage} />
</Switch>
</div>
);
export default App;
My login component grabs the cookie from express (fetch) and then does a <Redirect to='/' />
This loads up my Landing page, where I'm able to grab the cookie, but how do I get the cookie to the Topnav? I saw an answer to something like this on stack where it seems like App.js grabs the cookie and passes it as a props to the components, but I don't see how it could if it never refreshes. I've thought about forcing an entire window refresh (which does work for Topnav when I do a refresh manually), but I've also seen answers here that say don't do that.
Use Context
You need to use the new context hook from react.
Create a context
This is a context that you can access around your app.
const MyContext = React.createContext(defaultValue);
Make a provider
Wrap the provider around your main app
<MyContext.Provider value={/* some value */}>
Access the context at the point at which you get the cookies
Use this in both your login and top nav to use the value from the context
const value = useContext(MyContext);
There are multiple ways to approach this.
Probably a beginner friendly one.
When your login Component does the login successfully you need to signal to the App Component about it probably using a onLoginSuccessful which can then read the cookie and do a setState with it and use this component state value in the props to your Topnav and Landing Component
I'm trying to create an Electron app using React, React-router and Redux. What I'm finding is that my routing logic works absolutely fine when I'm nesting the switch/route logic under a purely presentational component (Page), but that I'm forced to refresh the page to see navigational changes if nested under a 'smart' container component.
Near the top of my React component hierarchy (right beneath HashRouter) I have a Page:
export default function Page (props) {
return (
<div className={`${styles.page}`}>
<SideBar/>
<DetailPane>{props.children}</DetailPane>
</div>
);
}
Here, DetailPane and SideBar are both container components wrapped around presentational components of the same name.
At startup (and during hot reloads), I create my React hierarchy using this function:
export default () => (
<Router>
<Page>
<Switch>
<Route exact path='/txDefinitions/:definitionName/:fieldName' component={FieldPage}/>
<Route exact path='/txDefinitions/:definitionName?' component={DefinitionPage}/>
<Route exact path='/rxDefinitions/:definitionName?' component={DefinitionPage}/>
<Route exact path='/'/>
<Route component={Route404}/>
</Switch>
</Page>
</Router>
This means that <Switch>...</Switch> gets nested underneath <DetailPane>.
If I try to navigate around my app (clicking links in the side bar), I won't actually see the detail pane render the new component until I force-reload the Electron app.
However, I find that routing works as expected if I omit DetailPane from Page:
export default function Page (props) {
return (
<div className={`${styles.page}`}>
<SideBar/>
{props.children}
</div>
);
}
Here is my React hierarchy without DetailPane (works fine):
Here is my React hierarchy with DetailPane (does not work right):
(Apologies for using images but I'm not sure if there's a way to copy from React devtools into clipboard - appears larger if opened in a new tab).
As I was writing this question, I realised this wouldn't be a huge issue for me because earlier refactoring had made the 'smart' version of DetailPane apparently obsolete. Using the purely presentational version of DetailPane
instead resolves this issue:
import * as React from 'react';
//import {DetailPane} from '../../containers'; // Smart/Redux
import {DetailPane} from '../../components'; // Dumb/presentational
import {SideBar} from '../../containers/';
const styles = require('./Page.scss');
export default function Page (props) {
return (
<div className={`${styles.page}`}>
<SideBar/>
<DetailPane>{props.children}</DetailPane>
</div>
);
}
However, I'm still curious why this doesn't work for the container component version. For reference, this is the container component version of DetailPane:
import {connect} from 'react-redux';
import {DetailPane} from '../../components';
// TODO: delete this container?
function mapStateToProps (state): {} {
return {};
}
function mapDispatchToProps (dispatch) {
// TODO.
return {};
}
export default connect(mapStateToProps, mapDispatchToProps)(DetailPane);
The connect HOC implements shouldComponentUpdate logic so if the props don't change, the component doesn't update.
To prevent this from occurring, and have the component always render, you can override the pure option in the connect call.
export default connect(mapStateToProps, mapDispatchToProps, undefined, { pure: false })(DetailPane);
See the react-redux API docs for more details.