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Redux store value set in callback

new to react-redux.I am facing a problem while working with redux store.
Data for store is loaded from API.Flow of my code is as follows:
app.js:
import React from 'react';
import { Provider } from 'react-redux';
import store from './store';
import Schema from './components/Schema';
import './styles/bootstrap.css';
import './styles/main.css';
export default class App{
constructor(props) {
super(props);
this.state = { store: {}};
}
componentWillMount(){
store(storeObject => {
this.setState({store: storeObject});
});
}
render(){
return <Provider store={ this.state.store }><Schema /></Provider>
}
}
store/index.js:
export default function(next) {
getInitialState(function(initialState) {
store = createStore(Reducers, initialState, compose(applyMiddleware(...middleware), extension));
console.log(store);//returning correct store value
next(store);
});
};
main.js:
import React from 'react';
import { render } from 'react-dom';
import { AppContainer } from 'react-hot-loader';
import App from './app.js';
const dom = document.getElementById('root');
render(
<AppContainer>
<App />
</AppContainer>,
dom
);
it is giving following error.

The store function which I guess is a reference to the getStore function doesn't return anything which means that App doesn't return anything hence the exception.
Because getStore does an async operation, you'll have to do something like this:
export default class App extends Component{
componentWillMount(){
store(storeObject => {
this.setState({store: storeObject});
});
}
render(){
return <Provider store={ this.state.store }><Schema /></Provider>
}
}

Print value from props, which is delivered to the component from redux by mapStateToProps

Problem:
I can't display the value from the state of redux, which is delivered by mapStateToProps function to the component.
Project structure:
Create-react-app CLi application built the project.
Inside of the src/ I have the following code structure
Necessary code:
The main page which we are interacting with looks like this:
Underneath it is planned to post the result of the clicking on the buttons.
So how do I bind the redux state and actions to those two components: Calculator and ResultLine?
Let me show the index.js code, where I create the store:
import React from "react";
import ReactDOM from "react-dom";
import { Provider } from "react-redux";
import { createStore } from "redux";
import reducers from './reducers/';
import App from './components/App';
ReactDOM.render(
<Provider store={createStore(reducers)}>
<App />
</Provider>,
document.getElementById("root")
);
There are only three actions:
import {CALCULATE, ERASE, PUT_SYMBOL} from "./types";
export const putSymbol = (symbol) => {
return {
type: PUT_SYMBOL,
payload: symbol
}
};
export const calculate = () => {
return {
type: CALCULATE
}
};
export const erase = () => {
return {
type: ERASE
}
};
And in the App.js I pass reducers, which are binded to those actions to the Calculator component:
import React, {Component} from 'react';
import Calculator from './Calculator';
import ResultLine from "./ResultLine";
import {calculate, erase, putSymbol} from "../actions/index";
import {connect} from "react-redux";
class App extends Component {
render() {
return (
<div>
<Calculator
onSymbolClick={this.props.onSymbolClick}
onEqualsClick={this.props.onEqualsClick}
onEraseClick={this.props.onEraseClick}/>
<br/>
<ResultLine result={this.props.result}/>
</div>
);
}
}
const mapStateToProps = (state) => {
console.log('mapState', state.calc.line);
return {
result: state.line
}
};
const mapDispatchToProps = {
onSymbolClick: putSymbol,
onEqualsClick: calculate,
onEraseClick: erase
};
export default connect(mapStateToProps, mapDispatchToProps)(App);
And that works fine. Whenever I click the button the state changes, and I observe it in the console log, called in mapStateToProps function.
So I expect, that I can deliver result prop to the Result line easily, and I pass it into the ResultLine component as a parameter. So, let's look at that element:
import React from 'react';
const ResultLine = ({result}) => {
return (
<p>{result}</p>
);
};
export default ResultLine;
And I can see no changes in a result line. Maybe, something wrong with the React/Redux lifecycle management and ResultLine component just does not update on changes in state?

There's an error on mapStateToProps.
Instead of:
const mapStateToProps = (state) => {
return {
result: state.line
}
}
Please use:
const mapStateToProps = (state) => {
return {
result: state.calc.line // calc was missing here
}
}

--How do I get access to my container/store in this top level file?

I'm just getting started with React/Redux and have everthing working fine with Redux when I test it.
However, I am not able to connect it into my actual application.
I assume I should use connect(), but I don't know how/where to.
// libraries
import React from 'react';
import ReactDOM from 'react-dom';
// redux
import { Provider } from 'react-redux';
import store from './redux/store';
import './redux/test.js';
import {connect} from 'react-redux'
class App extends React.Component {
constructor(props, test) {
super(props);
}
render () {
return (
<div id = 'contents'>
</div>
)
}
}
const app = document.getElementById('app');
ReactDOM.render(
<Provider store={store}>
<App></App>
</Provider>
, app);

You need to connect your component App.
By example let's assume you have value in your reducer named reducer in your store :
// libraries
import React from 'react';
import ReactDOM from 'react-dom';
// redux
import { Provider } from 'react-redux';
import store from './redux/store';
import './redux/test.js';
import {connect} from 'react-redux'
class App extends React.Component {
constructor(props, test) {
super(props);
}
render () {
// You can use data from props
return (
<div id = 'contents'>
{this.props.data}
</div>
)
}
}
const mapStateToProps = (state, ownProps) => {
// Bind your store state to the component data
return {
date: state.reducer.value,
};
}
const mapDispatchToProps = (dispatch) => {
// Bind actions to your component
}
const ConnectedApp = connect(mapStateToProps, mapDispatchToProps)(App);
const app = document.getElementById('app');
ReactDOM.render(
<Provider store={store}>
<ConnectedApp></ConnectedApp >
</Provider>
, app);

so what you need is to wrap App with the function returned by connect:
const AppWithRedux = connect()(App);
ReactDOM.render(
<Provider store={store}>
<AppWithRedux/>
</Provider>,
app);
But you can find a good example about how to integrate redux with react in the following link:
http://redux.js.org/docs/basics/UsageWithReact.html

state.getStore() or mapStateToProps - React.js / Redux

So I'm building my first Redux project to learn it. I just got it to output updated state in the middleware logger so that was great.
Now I am trying to have the component update based on the updated state.
Obviously I'm missing some fundamental concept here...I think I'm supposed to mapStateToProps but I just don't understand it.
Isn't there some simple global thing I can use?
How come when I console out store.getState().quote it works but doesn't update the component?
QUOTE COMPONENT
import React from 'react';
import { connect } from 'react-redux';
import { applyMiddleware, createStore } from 'redux';
import thunk from 'redux-thunk';
import promise from 'redux-promise';
import createLogger from 'redux-logger';
import quoteReducer from './reducers/quoteReducer';
const logger = createLogger();
const store = createStore(
quoteReducer,
applyMiddleware(thunk, promise, logger)
);
class quote extends React.Component {
componentWillMount() {
let req = new XMLHttpRequest();
req.responseType = "json";
req.onload = function(){
store.dispatch({type: "ADD_QUOTE", text: req.response.quote, movie: req.response.author});
}.bind(this)
req.open("GET", "http://localhost:3001/quote");
req.send();
}
render(){
return (
<div id="quote">
<h1> "{store.getState().quote}" </h1>
<h2> -{store.getState().author} </h2>
</div>
)
}
}
export default connect()(quote);
REDUCER
const quoteReducer = (state = {quote: "", author: ""}, action) => {
switch (action.type) {
case 'ADD_QUOTE':
return {
quote: action.text,
author: action.movie
}
default:
return state
}
}
export default quoteReducer;
ACTION
export const addQuote = (text, movie) => {
return {
type: "ADD_QUOTE",
text,
movie
}
}
APP.JS
import React, { Component } from 'react';
import Quote from './quote';
import AnswerInput from './answerInput';
import logo from './logo.svg';
import './App.css';
import './quote.css';
import './answerInput.css';
import './assets/styles/global.css';
class App extends Component {
render() {
return (
<div className="App">
<Quote />
<AnswerInput />
</div>
);
}
}
export default App;
INDEX.JS
import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';
import { Provider } from 'react-redux';
import { createStore } from 'redux';
import quoteReducer from './reducers/quoteReducer.js';
import './index.css';
let store = createStore(quoteReducer);
ReactDOM.render(
<Provider store={store}>
<App />
</Provider>,
document.getElementById('root')
);

The answer from #Konstantin Vitkovsky is sort of right, but not exactly.
There's a few problems with your original example:
First, your quote component should have a capitalized name, like Quote. React and JSX use capitalization to know whether you're trying to render a component or an individual tag. First letter uppercase means it's a component, first letter lowercase means it must be a tag.
Second, your component is currently accessing the store directly, and calling store.getState() in its render method. This will work the first time, but because your component has no idea when the store updates, it will not trigger a re-render. (Also, in React, ideally a render() method should only render things based on this.props and this.state.)
Third, you are calling the React-Redux connect method at the end of your file, but you're not actually using it in any way.
Finally, you definitely shouldn't refer to the store directly in the component. You should render a <Provider store={store}> component at the top of your component tree, which will make the store accessible to any connected component inside of it.
As #Konstantin Vitkovsky said, your component will not know that the store has been updated unless your component subscribes to the store. However, that is exactly what connect already does for you. Every time the store updates, the wrapper component generated by connect will re-run the mapStateToProps function you gave it, and pass the data that you return into your "real" component.
So, for your example, your code should look roughly like this:
import React, {Component} from "react";
import ReactDOM from "react-dom";
import {Provider, connect} from "react-redux";
const store = createStore(rootReducer);
// Normally the store definition and the component would be
// defined in different files
class Quote extends Component {
render() {
const {quote, author} = this.props;
return (
<div id="quote">
<h1>{quote}</h1>
<h2>{author}</h2>
</div>
);
}
}
const mapStateToProps = (state) => {
return {
quote : state.quote,
author : state.author
};
}
const ConnectedQuote = connect(mapStateToProps)(Quote);
ReactDOM.render(
<Provider store={store}
<Quote />
</Provider>,
document.getElementById("root")
);
I'd encourage you to read through the Redux docs thoroughly - they contain a lot of good information. Also, I keep a big list of links to high-quality tutorials and articles on React, Redux, and related topics, at https://github.com/markerikson/react-redux-links . It's specifically intended to be a great starting point for anyone trying to learn the ecosystem.

I ended up getting some help from a contact and this is the code that worked!
import React from 'react';
import { connect } from 'react-redux';
import { addQuote } from './actions';
const mapStateToProps = (state) => {
const { quote } = state;
return quote; //This would be the job for selectors (from advanced redux tutorial)
}
const mapDispatchToProps = (dispatch) => ({
addQuote(req) {
const { quote, author } = req.response;
dispatch(addQuote(quote, author)); // Use the action creator
}
})
class Quote extends React.Component {
componentWillMount() {
let req = new XMLHttpRequest();
req.responseType = "json";
req.onload = function(){
this.props.addQuote(req);
}.bind(this)
req.open("GET", "http://localhost:3001/quote");
req.send();
// the whole bit above is best replaced with a redux-fetch middleware
}
render(){
const {quote, author} = this.props;
return (
<div id="quote">
<h1> "{quote}" </h1>
<h2> -{author} </h2>
</div>
)
}
}
const ConnectedQuote = connect(mapStateToProps, mapDispatchToProps)(Quote);
export default ConnectedQuote;

React + Redux: Component does not update

Trying out React + Redux, and probably am doing something obviously stupid, because a component that fires an action to fetch data over the network does not get updated (re-rendered) when the data is fetched.
Here are the relevant bits of my code:
The top-level index.js serving as an entry point for the app:
import React from 'react';
import ReactDOM from 'react-dom';
import { Provider } from 'react-redux';
import { createStore, applyMiddleware } from 'redux';
import { Router, browserHistory } from 'react-router';
import reduxPromise from 'redux-promise';
import createLogger from 'redux-logger';
const logger = createLogger();
import routes from './routes';
import reducers from './reducers';
const createStoreWithMiddleware = applyMiddleware(reduxPromise, logger)(createStore);
ReactDOM.render(
<Provider store={createStoreWithMiddleware(reducers)}>
<Router history={browserHistory} routes={routes} />
</Provider>
, document.querySelector('.container'));
Top-level container App:
import React, {Component} from 'react';
import { bindActionCreators } from 'redux';
import { connect } from 'react-redux';
import * as Actions from '../actions';
import Header from '../components/header';
import Showcase from '../components/showcase';
function mapStateToProps(state) {
return {
resources: state.resources
}
}
function mapDispatchToProps(dispatch) {
return {
fetchResources: () => {
dispatch(Actions.fetchResources());
}
}
}
class App extends Component {
render() {
console.log('props in App', this.props);
return (
<div>
<Header/>
<Showcase
fetchResources={this.props.fetchResources}
resources={this.props.resources}
/>
</div>
);
}
}
export default connect(
mapStateToProps,
mapDispatchToProps
)(App)
Component that triggers an action to sends a request for data when it is about to mount and is supposed to show the fetched data:
import React, {Component} from 'react';
import {connect} from 'react-redux';
class Showcase extends Component {
constructor(props) {
super(props);
}
componentWillMount() {
this.props.fetchResources();
}
render() {
console.log('resources', this.props);
return (
<div>
This is showcase
</div>
);
}
}
export default connect(state => ({resources: state.resources}))(Showcase)
Action Creator:
import * as types from '../constants/ActionTypes';
import axios from 'axios';
export function fetchResources() {
return {
type: types.FETCH_FIRST,
payload: axios.get('/sampledata/1.json')
}
}
Reducer for the fetch action:
import * as types from '../constants/ActionTypes';
export default function resourcesReducer (state={}, action) {
switch (action.type) {
case types.FETCH_FIRST:
console.log('about to return', Object.assign (state, {resources: action.payload.data }))
return Object.assign (state, {resources: action.payload.data });
default:
return state
}
};
and finally the root reducer:
import { combineReducers } from 'redux';
import navigationReducer from './navigation-reducer';
import resourcesReducer from './resources-reducer';
const rootReducer = combineReducers({
navigationReducer,
resourcesReducer
});
export default rootReducer;
So, here is what I am observing. The action to request data is successfully triggered, a request is sent, the reducer receives it when the promise is resolved, and updates the state with the fetched data. At this point, I would expect the top-level App component and the Showcase component to detect that the store has updated, and to re-render, but I do not see it in the console.
Also, I am confused by redux-logger’s console output:
Specifically, I am surprized to see that the state contains reducers from the rootReducer — I don't know if it's right (an example on Redux logger Github page shows a state without reducers). It also seems surprising that the prev state as reported by redux-logger contains the same resourcesReducer object as the next state, although intuitively I would expect prev state to be more or less empty.
Could you please point out what I am doing wrong and how to get React components respond to the state changes?
==================================================
UPDATED:
1) Changed the mapStateToProps function in the App component so that it correctly maps to reducer states:
function mapStateToProps(state) {
return {
resources: state.resourcesReducer
}
}
2) Still passing the resources down to the `Showcase component:
render() {
console.log('props in App', this.props);
return (
<div>
<Header navigateActions={this.props.navigateActions}/>
React simple starter
<Showcase
fetchResources={this.props.fetchResources}
resources={this.props.resources}
/>
</div>
);
3) Trying to display resources on the screen by stringifying it to see what’s actually inside this object:
render() {
console.log('resources', this.props);
return (
<div>
This is showcase {JSON.stringify(this.props.resources)}
</div>
);
}
See this on the screen: This is showcase {}. The component does not seem to re-render.
Here’s the screenshot of the console showing that App’s props have updated with the values from the next state. Still, that did not cause the component to re-render:
UPDATED AGAIN: And my javascript-fu was poor, too. I did not quite realize that by returning Object.assign (state, {resources: action.payload.data }); I was in fact mutating the state, and that a simple inversion of arguments would let me achieve what I intended. Thanks to this discussion on SO for enlightenment.

I am surprized to see that the state contains reducers from the rootReducer
This is how it works. Take a closer look at combineReducers().
const rootReducer = combineReducers({
navigationReducer,
resourcesReducer
});
Recognise that it's not a list of parameters; it's a single object parameter. Perhaps it is clearer in verbose syntax:
var rootReducer = combineReducers({
navigationReducer: navigationReducer,
resourcesReducer: resourcesReducer
});
The resourcesReducer key points to the state returned by the resourcesReducer() function. That is, the state variable within the resourcesReducer() is just one part of the entire state.
The functions passed to connect() take the entire state as an argument. What yours should actually look like is this:
export default connect(state => ({
resources: state.resourcesReducer.resources
}))(Showcase);