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How to update react context provider state on button click

WebContext.js
import React, { createContext, Component } from 'react';
export const WebContext = createContext();
class WebContextProvider extends Component {
state = {
inputAmount: 1,
};
render() {
return <WebContext.Provider value={{ ...this.state }}>{this.props.children}</WebContext.Provider>;
}
}
export default WebContextProvider;
App.js
const App = () => {
return (
<WebContextProvider>
<UpdateBtn />
</WebContextProvider>
);
};
export default App;
UpdateBtn.js
const UpdateBtn = () => {
return (
<Div>
<Button onClick={} />
</Div>
);
};
export default UpdateBtn;
How do I update the inputAmount state present in WebContext.js on button click in UpdateBtn.js? App.js is the parent component for UpdateBtn.js Also, How can I convert the WebContext.js into a functional component?

You should pass the function in Provider which you can call to update the value:
WebContext.js
import React, { createContext, Component } from 'react';
export const WebContext = createContext();
class WebContextProvider extends Component {
state = {
inputAmount: 1,
};
render() {
return (
<WebContext.Provider
value={{
data: ...this.state, // all data now in context.data field
update: () => { // we added this callback
this.setState((state) => ({
inputAmount: state.inputAmount + 1,
}));
},
}}
>
{this.props.children}
</WebContext.Provider>
);
}
}
export default WebContextProvider;
App.js
const App = () => {
return (
<WebContextProvider>
<UpdateBtn />
</WebContextProvider>
);
};
export default App;
UpdateBtn.js
const UpdateBtn = () => {
const context = useContext(WebContext); // we use hook to get context value
return (
<Div>
<Button onClick={context.update} />
</Div>
);
};
export default UpdateBtn;
or
const UpdateBtn = () => {
// or we can use Consumer to get context value
return (
<Div>
<WebContext.Consumer>
{context => <Button onClick={context.update} />}
</WebContext.Consumer>
</Div>
);
};
export default UpdateBtn;

An alternative approach might be to use a reducer to update your state. For example:
export const initialState = {
inputValue: 1
}
export function reducer(state, action) {
const { type, payload } = action;
switch (type) {
case 'updateInputValue': {
return { ...state, inputValue: payload };
}
default: return state;
}
}
Import those into your provider file:
import { initialState, reducer } from './reducer';
and use useReducer to create a store:
export function WebContextProvider({ children }) {
const store = useReducer(reducer, initialState);
return (
<WebContext.Provider value={store}>
{children}
</WebContext.Provider>
);
}
You can then import the context into the component that needs it and use useContext to get at the state and dispatch method. On the click of the button you can dispatch a new value to the store to update inputValue.
export default function UpdateButton() {
const [ { inputValue }, dispatch ] = useContext(WebContext);
function handleClick(e) {
dispatch({
type: 'updateInputValue',
payload: inputValue + 1
});
}
return (
<div>
<div>{inputValue}</div>
<button onClick={handleClick}>Click</button>
</div>
);
};
I've created a full demo to show you how it works in harmony.

How to refresh state using React, Redux, and redux-form

Fairly new to these technologies and am at wit's end. I've got two components; a parent which contains a form (using redux-form) and writes a new record to a database, and a child which lists some data.
The only thing I can't get to work is refreshing that child list when the form submit completes. If I refresh the page, the new data is visible. From what I had read, it was my understanding that by wiring up redux-form, that my state would refresh automatically...or something like that. Am I even going about this the right way? Here's everything...
My index reducer:
import { combineReducers } from 'redux';
import { reducer as formReducer } from "redux-form";
import ItemsReducer from "../reducers/items";
const rootReducer = combineReducers({
form: formReducer,
items: ItemsReducer
});
export default rootReducer;
My items reducer:
import { GET_ALL_ITEMS } from "../actions/items";
export default (state = {}, action) => {
switch (action.type) {
case GET_ALL_ITEMS:
return action.payload.data;
default:
return state;
}
}
My actions:
import axios from "axios";
export const GET_ALL_ITEMS = "GET_ALL_ITEMS";
export const SAVE_ITEM = "SAVE_ITEM";
const ROOT_API_URL = "http://myapi:3000/api";
export function getAllItems() {
let request = axios.get(`${ROOT_API_URL}/items`);
return {
type: GET_ALL_ITEMS,
payload: request
};
}
export function saveItem(item, callback) {
let request = axios
.post(`${ROOT_API_URL}/item`, item)
.then(() => callback());
return {
type: SAVE_ITEM,
payload: request
};
}
The (abbreviated) parent (list and form):
import ItemsList from "./items_list";
...
onSubmit = (item) => {
let { saveItem } = this.props;
saveItem(item, () => {
// this is successful
});
}
...
//the list in render()
<div>
<ItemsList />
</div>
...
//redux-form wired up at bottom
export default reduxForm({
form: "EditItemForm",
})(connect(null, { saveItem })(Items));
The child component:
import React, { Component } from "react";
import { connect } from "react-redux";
import { Link } from "react-router-dom";
import { getAllItems } from "../actions/items";
class Shows extends Component {
componentDidMount() {
this.props.getAllItems();
}
render() {
return(
<div className="body-content-partial">
{this.renderItems()}
</div>
);
}
renderItems() {
let { items } = this.props;
return items.map(item => {
return(
<a href="#" key={item.id}>
<div className="list-item-noavatar list-lines-div">
<div className="list-title">
{item.name}
</div>
<div className="status-div">
<span className="status-indicator"></span>
{item.active}
</div>
</div>
</a>
);
});
}
}
function mapStateToProps(state) {
return { items: state.items };
}
export default connect(mapStateToProps, { getAllItems })(Items);

OK, absolutely fixed it this time. I had to make a call to getAllItems() on the form submit as well as pass it into the dispatch portion of the connect() call, for the redux-form setup. Respectively:
import { saveItem, getAllItems } from "../actions/items";
...
onSubmit = (item) => {
let { saveItem, onSave, getAllItems } = this.props;
saveItem(item, () => {
onSave();
getAllItems();
});
}
...
export default reduxForm({
form: "ItemEditForm",
})(connect(null, { saveItem, getAllItems })(ItemEditForm));

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)

React Redux - Setting Store and Updating UI using Navigation Menu

I'm extremely new to react/redux and very mediocre at Javascript, but I've been struggling with this for over a week now. Here's what I'm trying to do:
Clicking one of the navigation menu items on the left should dispatch an action to set the selected index in the store (at this point the entire store is just a number). When the index is updated it should automatically be reflected in the UI, at least by changing the css class of the selected item, but eventually it should toggle visibility for content components on the right.
Sidebar.js:
import React, { Component } from 'react';
import SidebarItem from './SidebarItem'
import ActionCreators from '../actions'
import { connect } from 'react-redux'
export default class Sidebar extends Component
{
handleClick(index)
{
//Dispatch action here maybe?
this.props.selectedSidebarItem(index);
console.log(this);
}
render()
{
var sidebarItemNames = ["Verify Original Contract", "Evaluate Transfer Terms", "Create Future Customer", "Check Credit", "Generate Agreement", "Finalize Transfer"];
return (
<div>
<div id="sidebar-title">
<div id="sc-logo">
LOGO
</div>
<div>Contract Transfer for:</div>
<div>XYZ</div>
<br />
</div>
<ul className="list-group" id="sidebar-list">
{sidebarItemNames.map(function(n, index)
{
return <SidebarItem key={index} index={index} selectedIndex={this.selectedSidebarItem} name={n} handleClick={this.handleClick(index).bind(this)} />;
})}
</ul>
</div>
)
}
}
function mapDispatchToProps(dispatch) {
return {
selectedSidebarItem: (index) => dispatch(ActionCreators.setSelectedSidebarItem(index))
}
}
const conn = connect(
null,
mapDispatchToProps
)(Sidebar)
SidebarItem.js:
import React, { Component } from 'react';
import ActionCreators from '../actions'
import { connect } from 'react-redux'
export class SidebarItem extends Component {
constructor(props) {
super(props);
}
setSelectedSidebarItem() {
this.props.handleClick(this.props.index);
this.props.selectedSidebarItem(this.props.index);
// const ul = document.getElementById('sidebar-list');
// const items = ul.getElementsByTagName('li');
// for (let i = 0; i < items.length; ++i) {
// items[i].classList.remove('sidebar-item-current');
// }
}
render() {
return (
<li className={"list-group-item sidebar-list-item sidebar-item-todo" + (this.props.index==this.props.selectedIndex? ' sidebar-item-current':'') } onClick={this.setSelectedSidebarItem.bind(this)}><i className="fa fa-circle fa-lg"></i> <span>{this.props.name}</span></li>
)
}
}
Store.js:
import { createStore } from 'redux'
import reducers from './Reducers'
const store = createStore(reducers)
export default store
Reducers.js
const initialState = {
selectedSidebarItem: window.initialPageState,
otherStuff: 5
};
const reducers = (state = initialState, action) => {
switch (action.type) {
case "SET_SELECTED_SIDEBAR_ITEM":
console.log("clicked sidebar index: " + action.index);
var result = Object.assign({}, state, {
selectedSidebarItem: action.index
})
console.log(result);
return result;
default:
return state
}
}
export default reducers
actions.js:
import constants from './constants'
let ActionCreators = {
setSelectedSidebarItem(index) {
var actionObject = {
type: constants.UPDATE_SELECTED_SIDEBAR_ITEM,
index
}
console.log("setting sidebar item", actionObject);
return actionObject
}
}
export default ActionCreators
Constants.js
const constants = {
UPDATE_SELECTED_SIDEBAR_ITEM: "UPDATE_SELECTED_SIDEBAR_ITEM",
ADD_ERROR: "ADD_ERROR",
CLEAR_ERROR: "CLEAR_ERROR"
};
export default constants;
I've tried a few variations of the above and have previously been able to dispatch actions, but am unsure the store is ever updated and nothing is reflected on the UI. Right now I'm getting this error when clicking sidebar items: "Cannot read property 'handleClick' of undefined"
Thanks for any help in advance.

in your sidebar.js:
instead of
handleClick={() => this.handleClick(index).bind(this)}
try this:
handleClick={this.handleClick(index).bind(this)}
And in handleClick method you have to dispatch action:
this.props.selectedSidebarItem(index)
Answer update:
import React, { Component } from 'react';
import SidebarItem from './SidebarItem'
import ActionCreators from '../actions'
import { connect } from 'react-redux'
export default class Sidebar extends Component
{
handleClick(index)
{
//Dispatch action here maybe?
this.props.selectedSidebarItem(index);
this.selectedSidebarItem = index;
console.log(this);
}
render()
{
var sidebarItemNames = ["Verify Original Contract", "Evaluate Transfer Terms", "Create Future Customer", "Check Credit", "Generate Agreement", "Finalize Transfer"];
return (
<div>
<div id="sidebar-title">
<div id="sc-logo">
LOGO
</div>
<div>Contract Transfer for:</div>
<div>XYZ</div>
<br />
</div>
<ul className="list-group" id="sidebar-list">
{sidebarItemNames.map(function(n, index)
{
return <SidebarItem key={index} index={index} selectedIndex={this.selectedSidebarItem} name={n} handleClick={this.handleClick(index).bind(this)} />;
})}
</ul>
</div>
)
}
}
function mapDispatchToProps(dispatch) {
return {
selectedSidebarItem: (index) => dispatch(ActionCreators.setSelectedSidebarItem(index))
}
}
const conn = connect(
null,
mapDispatchToProps
)(Sidebar)

Uncaught Invariant Violation: Expected onClick listener to be a function, instead got type object

I'm trying to define the click event listeners of NavigationButtons by injecting them via Redux's connect. However, those functions are not defined properly, even if they pass the propTypes validation. Sample below:
import React, { PropTypes } from "react"
import { connect } from "react-redux"
import { previousPage, nextPage } from "../actions"
const NavigationButtons = ( onPrevPageClick, onNextPageClick, firstPage = false ) => (
<div className="navigation-buttons">
{!firstPage && <div className="previous button" onClick={onPrevPageClick}>Previous Page</div>}
<div className="next button" onClick={onNextPageClick}>Next page</div>
<div className="clearfix"></div>
</div>
);
NavigationButtons.propTypes = {
onPrevPageClick: PropTypes.func.isRequired,
onNextPageClick: PropTypes.func.isRequired
};
const mapStateToProps = ({ page }) => {
return {
firstPage: page == 0
}
};
const mapDispatchToProps = (dispatch) => {
return {
onPrevPageClick: () => {
dispatch(previousPage())
},
onNextPageClick: () => {
dispatch(nextPage())
}
}
};
const NavigationButtonsContainer = connect(
mapStateToProps,
mapDispatchToProps
)(NavigationButtons);
export default NavigationButtonsContainer

The brackets in the function declaration were missing. It should be:
const NavigationButtons = ({ onPrevPageClick, onNextPageClick, firstPage = false })
Instead of:
const NavigationButtons = (onPrevPageClick, onNextPageClick, firstPage = false)