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Passing data from Main layout to subpages in Nextjs

I'm trying to do something like this;
I have a file called /components/master_layout.js and it has the following content:
import useUser from "../data/use-user";
function MasterLayout({ children }) {
const { data, error, mutate } = useUser();
if ( error ) return <div>error</div>
if ( !data && !error ) return <div>loading..</div>
return (
<div>
{children}
</div>
)
}
export default MasterLayout
In short, this layout file returns according to the response of the useuser function.
Here is an example of a page where I use this layout:
file path and name: /pages/dashboard/index.js
import MasterLayout from "../../components/master_layout";
function Dashboard() {
return (
<MasterLayout>
dashboard..
</MasterLayout>
)
}
export default Dashboard
Can I use useUser data from Layout in '/pages/dashboard/index.js' and my other pages?
The reason I want this is, I'm trying to do something like:
import MasterLayout from "../../components/master_layout";
function Dashboard({data}) {
return (
<MasterLayout>
Welcome back, {data.username}
</MasterLayout>
)
}
export default Dashboard
Do I have any other choice but to pull the useUser for each page one by one and transfer it to the master layout as

You can use HOC pattern in this case. Something like
// with-data.js
import React from "react";
import useUser from "../data/use-user";
const withData = (WrappedComponent) => {
class WithData extends React.Component {
constructor(props) {
super(props);
this.state = {
data: "",
};
}
componentDidMount() {
const { data, error, mutate } = useUser();
this.setState({data:data});
}
render() {
const { data, ...otherProps } = this.props;
return (
<WrappedComponent data={this.state.data}/>
)
//* See how we can enhance the functionality of the wrapped component
}
}
return WithData;
};
export default withData;
Now you can use the withData,
import MasterLayout from "../../components/master_layout";
import withData from "../withData.js"
function Dashboard({data}) {
return (
<MasterLayout>
Welcome back, {data.username}
</MasterLayout>
)
}
export default withData(Dashboard);
In fact wrapping around any component with withData, can access the data variable.

How to pass async state to child component props?

I'm new to react and I am trying to fetch data from an API and pass the data to a child component. I've passed the data to the state on my parent component, however, when I pass it to the child component as props it logs as an empty array. I'm sure there is something simple I am overlooking but I don't know what, my code is below
PARENT COMPONENT
import React, {Component} from 'react';
import Child from '../src/child';
import './App.css';
class App extends Component {
constructor(props) {
super(props);
this.state = {
properties: []
}
}
getData = () => {
fetch('url')
.then(response => {
return response.text()
})
.then(xml => {
return new DOMParser().parseFromString(xml, "application/xml")
})
.then(data => {
const propList = data.getElementsByTagName("propertyname");
const latitude = data.getElementsByTagName("latitude");
const longitude = data.getElementsByTagName("longitude");
var allProps = [];
for (let i=0; i<propList.length; i++) {
allProps.push({
name: propList[i].textContent,
lat: parseFloat(latitude[i].textContent),
lng: parseFloat(longitude[i].textContent)
});
}
this.setState({properties: allProps});
});
}
componentDidMount = () => this.getData();
render () {
return (
<div>
<Child data={this.state.properties} />
</div>
)
}
}
export default App;
CHILD COMPONENT
import React, {Component} from 'react';
class Child extends Component {
initChild = () => {
console.log(this.props.data); // returns empty array
const properties = this.props.data.map(property => [property.name, property.lat, property.lng]);
}
componentDidMount = () => this.initChild();
render () {
return (
<div>Test</div>
)
}
}
export default Child;

Change the componentDidMount in the child to componentDidUpdate.
The componentDidMount lifecycle method is called only once in the starting. Whereas, the componentDidUpdate lifecycle method gets called whenever there is a change in the state of the application. Since api calls are asynchronous, the initChild() function is already called once before the api call's results are passed to the child.

You can use conditional rendering
import React, {Component} from 'react';
class Child extends Component {
initChild = () => {
if(this.props.data){
const properties = this.props.data.map(property => [property.name, property.lat, property.lng]);
}
}
componentDidMount = () => this.initChild();
render () {
return (
<div>Test</div>
)
}
}
export default Child;

react and redux, update state from store changes in a component

I'm trying to update my home componentstate by getting data from the redux store every time the store is updated. I'm not sure what's wrong with the code below. I can't listen to store changes in my `home component.
my dispatch function is handled in this class.
export class GanttFilter extends Component {
...
handleSubmit = () => {
this.gFilter.filterGanttData(this.formValues)
.then((result) => {
if (result.data)
this.props.dispatch(ganttActions.loadGanttData(result.data));
});
}
...
GanttFilter.propTypes = {
dispatch: PropTypes.func.IsRequired
};
function mapStateToProps(state) {
return {
ganttData: state.gantt.ganttData
};
}
export default connect(mapStateToProps)(GanttFilter);
What I would like to do every time dispatch is called and the data changes, is update the state in my home component. Here is the component.
export class Home extends Component {
constructor() {
super();
this.state = {
data: [],
links: []
};
}
render() {
return (
<div className="fill">
<Gantt data={this.state.data} links={this.state.links} />
</div>
);
}
}
Home.propTypes = {
data: PropTypes.IsRequired
};
function mapStateToProps(state) {
return {
data: state.gantt.ganttData
};
}
export default connect(mapStateToProps)(Home);
the function mapStateToProps is never hit when I set a break point. How can I listen to changes to the store from the home component and update state?
Edit: Here is the wrapper component
function renderApp() {
// This code starts up the React app when it runs in a browser. It sets up the routing
// configuration and injects the app into a DOM element.
const baseUrl = document.getElementsByTagName("base")[0].getAttribute("href");
ReactDOM.render(
<ReduxProvider store={store}>
<AppContainer>
<BrowserRouter children={routes} basename={baseUrl} />
</AppContainer>
</ReduxProvider>,
document.getElementById("react-app")
);
}
reducers
const actionTypes = require('../actions/actionTypes');
const gantt = {
ganttData: [],
selectedTask: null
};
export default function ganttReducer(state = gantt, action) {
switch (action.type) {
case actionTypes.loadGanttData:
return { ...state, ganttData: [...action.ganttData] };
default:
return state;
}
}
root reducer
import { combineReducers } from 'redux';
import gantt from './ganttReducer';
const rootReducer = combineReducers({
gantt
});
export default rootReducer;
actions
const actionTypes = require('./actionTypes');
export function loadGanttData(ganttData) {
return { type: actionTypes.loadGanttData, ganttData };
}
export function getSelectedTask(ganttTask) {
return { type: actionTypes.setSelectedTask, ganttTask };
}
Error:

Make sure you import your Home component using import Home from '...' as opposed to import { Home } from '...', otherwise you'd be grabbing the unconnected component. In general, I would also avoid exporting the unconnected component.

Change this:
render() {
return (
<div className="fill">
<Gantt data={this.state.data} links={this.state.links} />
</div>
);
}
To
render() {
return (
<div className="fill">
<Gantt data={this.props.data} links={this.state.links} />
</div>
);
}
Your data is comming from your props (redux), not from your state.

How to pass in an instance variable from a React component to its HOC?

I typically use component composition to reuse logic the React way. For example, here is a simplified version on how I would add interaction logic to a component. In this case I would make CanvasElement selectable:
CanvasElement.js
import React, { Component } from 'react'
import Selectable from './Selectable'
import './CanvasElement.css'
export default class CanvasElement extends Component {
constructor(props) {
super(props)
this.state = {
selected: false
}
this.interactionElRef = React.createRef()
}
onSelected = (selected) => {
this.setState({ selected})
}
render() {
return (
<Selectable
iElRef={this.interactionElRef}
onSelected={this.onSelected}>
<div ref={this.interactionElRef} className={'canvas-element ' + (this.state.selected ? 'selected' : '')}>
Select me
</div>
</Selectable>
)
}
}
Selectable.js
import { Component } from 'react'
import PropTypes from 'prop-types'
export default class Selectable extends Component {
static propTypes = {
iElRef: PropTypes.shape({
current: PropTypes.instanceOf(Element)
}).isRequired,
onSelected: PropTypes.func.isRequired
}
constructor(props) {
super(props)
this.state = {
selected: false
}
}
onClick = (e) => {
const selected = !this.state.selected
this.setState({ selected })
this.props.onSelected(selected)
}
componentDidMount() {
this.props.iElRef.current.addEventListener('click', this.onClick)
}
componentWillUnmount() {
this.props.iElRef.current.removeEventListener('click', this.onClick)
}
render() {
return this.props.children
}
}
Works well enough. The Selectable wrapper does not need to create a new div because its parent provides it with a reference to another element that is to become selectable.
However, I've been recommended on numerous occasions to stop using such Wrapper composition and instead achieve reusability through Higher Order Components. Willing to experiment with HoCs, I gave it a try but did not come further than this:
CanvasElement.js
import React, { Component } from 'react'
import Selectable from '../enhancers/Selectable'
import flow from 'lodash.flow'
import './CanvasElement.css'
class CanvasElement extends Component {
constructor(props) {
super(props)
this.interactionElRef = React.createRef()
}
render() {
return (
<div ref={this.interactionElRef}>
Select me
</div>
)
}
}
export default flow(
Selectable()
)(CanvasElement)
Selectable.js
import React, { Component } from 'react'
export default function makeSelectable() {
return function decorateComponent(WrappedComponent) {
return class Selectable extends Component {
componentDidMount() {
// attach to interaction element reference here
}
render() {
return (
<WrappedComponent {...this.props} />
)
}
}
}
}
The problem is that there appears to be no obvious way to connect the enhanced component's reference (an instance variable) to the higher order component (the enhancer).
How would I "pass in" the instance variable (the interactionElRef) from the CanvasElement to its HOC?

I came up with a different strategy. It acts roughly like the Redux connect function, providing props that the wrapped component isn't responsible for creating, but the child is responsible for using them as they see fit:
CanvasElement.js
import React, { Component } from "react";
import makeSelectable from "./Selectable";
class CanvasElement extends Component {
constructor(props) {
super(props);
}
render() {
const { onClick, selected } = this.props;
return <div onClick={onClick}>{`Selected: ${selected}`}</div>;
}
}
CanvasElement.propTypes = {
onClick: PropTypes.func,
selected: PropTypes.bool,
};
CanvasElement.defaultProps = {
onClick: () => {},
selected: false,
};
export default makeSelectable()(CanvasElement);
Selectable.js
import React, { Component } from "react";
export default makeSelectable = () => WrappedComponent => {
const selectableFactory = React.createFactory(WrappedComponent);
return class Selectable extends Component {
state = {
isSelected: false
};
handleClick = () => {
this.setState({
isSelected: !this.state.isSelected
});
};
render() {
return selectableFactory({
...this.props,
onClick: this.handleClick,
selected: this.state.isSelected
});
}
}
};
https://codesandbox.io/s/7zwwxw5y41
I know that doesn't answer your question. I think you're trying to let the child get away without any knowledge of the parent.
The ref route feels wrong, though. I like the idea of connecting the tools to the child. You can respond to the click in either one.
Let me know what you think.

Just as you did on DOM element for CanvasElement, Ref can be attached to class component as well, checkout the doc for Adding a Ref to a Class Component
export default function makeSelectable() {
return function decorateComponent(WrappedComponent) {
return class Selectable extends Component {
canvasElement = React.createRef()
componentDidMount() {
// attach to interaction element reference here
console.log(this.canvasElement.current.interactionElRef)
}
render() {
return (
<WrappedComponent ref={this.canvasElement} {...this.props} />
)
}
}
}
}
Also, do checkout Ref forwarding if you need child instance reference in ancestors that's multiple levels higher in the render tree. All those solutions are based on assumptions that you're on react 16.3+.
Some caveats:
In rare cases, you might want to have access to a child’s DOM node from a parent component. This is generally not recommended because it breaks component encapsulation, but it can occasionally be useful for triggering focus or measuring the size or position of a child DOM node.
While you could add a ref to the child component, this is not an ideal solution, as you would only get a component instance rather than a DOM node. Additionally, this wouldn’t work with functional components. https://reactjs.org/docs/forwarding-refs.html

I've now come up with an opinionated solution where the HoC injects two callback functions into the enhanced component, one to register the dom reference and another to register a callback that is called when an element is selected or deselected:
makeElementSelectable.js
import React, { Component } from 'react'
import PropTypes from 'prop-types'
import movementIsStationary from '../lib/movement-is-stationary';
/*
This enhancer injects the following props into your component:
- setInteractableRef(node) - a function to register a React reference to the DOM element that should become selectable
- registerOnToggleSelected(cb(bool)) - a function to register a callback that should be called once the element is selected or deselected
*/
export default function makeElementSelectable() {
return function decorateComponent(WrappedComponent) {
return class Selectable extends Component {
static propTypes = {
selectable: PropTypes.bool.isRequired,
selected: PropTypes.bool
}
eventsAdded = false
state = {
selected: this.props.selected || false,
lastDownX: null,
lastDownY: null
}
setInteractableRef = (ref) => {
this.ref = ref
if (!this.eventsAdded && this.ref.current) {
this.addEventListeners(this.ref.current)
}
// other HoCs may set interactable references too
this.props.setInteractableRef && this.props.setInteractableRef(ref)
}
registerOnToggleSelected = (cb) => {
this.onToggleSelected = cb
}
componentDidMount() {
if (!this.eventsAdded && this.ref && this.ref.current) {
this.addEventListeners(this.ref.current)
}
}
componentWillUnmount() {
if (this.eventsAdded && this.ref && this.ref.current) {
this.removeEventListeners(this.ref.current)
}
}
/*
keep track of where the mouse was last pressed down
*/
onMouseDown = (e) => {
const lastDownX = e.clientX
const lastDownY = e.clientY
this.setState({
lastDownX, lastDownY
})
}
/*
toggle selected if there was a stationary click
only consider clicks on the exact element we are making interactable
*/
onClick = (e) => {
if (
this.props.selectable
&& e.target === this.ref.current
&& movementIsStationary(this.state.lastDownX, this.state.lastDownY, e.clientX, e.clientY)
) {
const selected = !this.state.selected
this.onToggleSelected && this.onToggleSelected(selected, e)
this.setState({ selected })
}
}
addEventListeners = (node) => {
node.addEventListener('click', this.onClick)
node.addEventListener('mousedown', this.onMouseDown)
this.eventsAdded = true
}
removeEventListeners = (node) => {
node.removeEventListener('click', this.onClick)
node.removeEventListener('mousedown', this.onMouseDown)
this.eventsAdded = false
}
render() {
return (
<WrappedComponent
{...this.props}
setInteractableRef={this.setInteractableRef}
registerOnToggleSelected={this.registerOnToggleSelected} />
)
}
}
}
}
CanvasElement.js
import React, { PureComponent } from 'react'
import { connect } from 'react-redux'
import { bindActionCreators } from 'redux'
import PropTypes from 'prop-types'
import flowRight from 'lodash.flowright'
import { moveSelectedElements } from '../actions/canvas'
import makeElementSelectable from '../enhancers/makeElementSelectable'
class CanvasElement extends PureComponent {
static propTypes = {
setInteractableRef: PropTypes.func.isRequired,
registerOnToggleSelected: PropTypes.func
}
interactionRef = React.createRef()
componentDidMount() {
this.props.setInteractableRef(this.interactionRef)
this.props.registerOnToggleSelected(this.onToggleSelected)
}
onToggleSelected = async (selected) => {
await this.props.selectElement(this.props.id, selected)
}
render() {
return (
<div ref={this.interactionRef}>
Select me
</div>
)
}
}
const mapStateToProps = (state, ownProps) => {
const {
canvas: {
selectedElements
}
} = state
const selected = !!selectedElements[ownProps.id]
return {
selected
}
}
const mapDispatchToProps = dispatch => ({
selectElement: bindActionCreators(selectElement, dispatch)
})
const ComposedCanvasElement = flowRight(
connect(mapStateToProps, mapDispatchToProps),
makeElementSelectable()
)(CanvasElement)
export default ComposedCanvasElement
This works, but I can think of at least one significant issue: the HoC injects 2 props into the enhanced component; but the enhanced component has no way of declaratively defining which props are injected and just needs to "trust" that these props are magically available
Would appreciate feedback / thoughts on this approach. Perhaps there is a better way, e.g. by passing in a "mapProps" object to makeElementSelectable to explicitly define which props are being injected?

Reactjs, reducers, language switching

I have just taken over a new reactjs project -- and I am trying to review how language switching has been invoked.
so like there are two links in the footer to do this language switch.
//footer.js
import React from 'react'
import { Link } from 'react-router-dom'
import { connect } from 'react-redux'
import { bindActionCreators } from 'redux'
import { selectLanguage, getLangDetails } from '../../actions/action_language'
import langObject from './Footer.lang'
class Footer extends React.Component {
constructor (props) {
super(props)
this.changeLanguageToGerman = this.changeLanguageToGerman.bind(this)
this.changeLanguageToEnglish = this.changeLanguageToEnglish.bind(this)
}
changeLanguageToGerman () {
this.props.selectLanguage('de')
}
changeLanguageToEnglish () {
this.props.selectLanguage('en')
}
render () {
let activeLang = 'language--active'
let alternativeLang = 'language--hover'
const lang = getLangDetails(this.props.active_language, langObject)
return (
<div>
<footer className='main-footer show-for-medium-only'>
<div className='medium-15 columns'>
<p className='text--white grid__row--offset--15 footer-text'>
<Link to={this.props.deURL} className={`text--white footer-text ${this.props.active_language === 'de' ? activeLang : alternativeLang}`} onClick={this.changeLanguageToGerman}>DE</Link>
|
<Link to={this.props.enURL} className={`text--white footer-text ${this.props.active_language === 'en' ? activeLang : alternativeLang}`} onClick={this.changeLanguageToEnglish}>EN</Link>
</p>
</div>
</footer>
</div>
)
}
}
const mapStateToProps = (state) => {
return {
active_language: state.active_language
}
}
function mapDispatchToProps (dispatch) {
return bindActionCreators({selectLanguage: selectLanguage}, dispatch)
}
const { string, func } = React.PropTypes
Footer.propTypes = {
deURL: string,
enURL: string,
selectLanguage: func,
active_language: string
}
export default connect(mapStateToProps, mapDispatchToProps)(Footer)
// header.js
import React from 'react'
import { connect } from 'react-redux'
import { getLangDetails } from '../../actions/action_language'
import langObject from './Header.lang'
class Header extends React.Component {
render () {
let transparent
transparent = this.props.transparent ? 'transparent' : ''
const lang = getLangDetails(this.props.active_language, langObject)
return (
<div>
<header className={` main_headerbar__landing transition show-for-large-up ${transparent} `}>
<div className='contain-to-grid'>
{lang}
</div>
</header>
</div>
)
}
}
const mapStateToProps = (state) => {
return {
active_language: state.active_language
}
}
const { bool, string } = React.PropTypes
Header.propTypes = {
transparent: bool,
active_language: string
}
export default connect(mapStateToProps)(Header)
--- so these are the header/footer components - and each has a json file that splits into an array of lang.
there is a file that looks like some global js that I think hooks into this - but I am struggling to extend this functionality into the rest of the site components/pages
//action_language.js
export const LANGUAGE_SELECTED = 'LANGUAGE_SELECTED'
export function selectLanguage (language) {
return {
type: LANGUAGE_SELECTED,
payload: language
}
}
export function getLangDetails (language = 'de', langObject) {
const langData = langObject.langs.filter((langVar) => langVar.lang === language)
return langData['0'].lines
}
ok - so here is the first page -- called services. Now what throws me first here is rather than use active_language its now just language.
//services.js
import React from 'react'
import Header from '../HeaderLanding/Header'
import Footer from '../Footer/Footer'
import NoBundle from './NoBundle'
import HowTiles from './HowTiles'
import CarouselTiles from './CarouselTiles'
import YourAdvantages from './YourAdvantages'
import InformationTiles from './InformationTiles'
import ContactTiles from './ContactTiles'
import { connect } from 'react-redux'
import { bindActionCreators } from 'redux'
import { selectLanguage, getLangDetails } from '../../actions/action_language'
// language file
import langObject from './services.lang.json'
// services css
import './services.css'
// getting the distinct URLs from the lang files
const deURL = langObject.langs[0].pageURL
const enURL = langObject.langs[1].pageURL
const Spacers = () => (
<div>
<div className='row show-for-large-up' style={{ height: '250px' }} />
<div className='row show-for-medium-only' style={{ height: '150px' }} />
<div className='row show-for-small-only' style={{ height: '80px' }} />
</div>
)
class Services extends React.Component {
constructor (props) {
super(props)
this.language = props.match.params.langURL
}
componentWillMount () {
document.getElementById('body').className = 'overlay-background-services'
this.updateLanguage()
}
updateLanguage () {
console.log('updatelang', this.language)
if (this.language === 'de' || !this.language) {
this.props.selectLanguage('de')
} else {
this.props.selectLanguage('en')
}
}
componentWillUnmount () {
document.getElementById('body').className = ''
}
render () {
const lang = getLangDetails(this.language, langObject)
return (
<div>
<Header transparent />
<Spacers />
<NoBundle lang={lang} />
<HowTiles />
<CarouselTiles />
<YourAdvantages />
<InformationTiles />
<ContactTiles />
<Footer deURL={deURL} enURL={enURL} />
</div>
)
}
}
const mapStateToProps = (state) => {
return {
language: state.language
}
}
function mapDispatchToProps (dispatch) {
return bindActionCreators({selectLanguage: selectLanguage}, dispatch)
}
const { func, string, object } = React.PropTypes
Services.propTypes = {
selectLanguage: func,
langURL: string,
params: object,
match: object
}
export default connect(mapStateToProps, mapDispatchToProps)(Services)

The Footer component deals with setting the current language by invoking the Redux action creator selectLanguage. Essentially this dispatches an action (you can think of this as a custom event with some corresponding data - the language) to the store that will persist the user's language selection for use elsewhere.
In order to consume the language in other components, that language selection needs to be passed into the component (in this case the Header) from the Redux store.
This is the code of interest in header that does that...
const mapStateToProps = (state) => {
return {
active_language: state.active_language
}
}
export default connect(mapStateToProps)(Header)
Here you are connecting the Header to the store, with a function that describes how the store should map values into props on your react component. state.active_language is where the language that the user has selected is stored, and this is telling it to be passed as a prop called active_language on your Header component
The connect function is a decorator that will create what's know as a Higher Order Component (HOC) which is essentially a component with props or functionality automatically injected into it (decorated in this case with an automatically passed value for the active_language prop from the store)
You can do the same for any other component that need this language setting, or go a step or two further
Instead of passing the active language name, pass the corresponding language itself...
import { getLangDetails } from '../../actions/action_language'
import langObject from './Header.lang'
const mapStateToProps = (state) => {
return {
active_language: getLangDetails(state.active_language, langObject)
}
}
export default connect(mapStateToProps)(Header)
OR better yet write another HOC that wraps any component you pass with this info...
import { getLangDetails } from '../../actions/action_language'
export default const injectLanguage = (component, langObject) => connect((state) => ({
language: getLangDetails(state.active_language, langObject)
})
)(component)
Then in subsequent components with a language prop, decorate with this
import injectLanguage from './some/where'
import langObject from './MyLanguageDetailsAwareComponent.lang'
class MyLanguageDetailsAwareComponent extends React.Component {
render() {
return this.props.language
}
}
export default injectLanguage(MyLanguageDetailsAwareComponent, langObject)