In this project, you’ll connect Redux to a React application. You'll configure a Redux store, create Redux reducers and action creators, and use them in a Grocery Store application to add produce to a shopping cart. You'll also learn how to normalize data in a Redux store.

When you finish today's project, your application should have the following features:

• Display all the produce in a list
• Add produce to a cart
• Increment/decrement the quantity of produce in the cart
• Checkout the cart

Clone the starter repository from the Download link below.

Run npm install and npm start to start the development server.

Navigate to http://localhost:3000. You should see the text "Grocery Store". If you click on the "Checkout" button in the navigation bar, it should open a side menu. Since there is no produce listed, you cannot add items to the shopping cart yet.

The Cart, ProduceList, and ProduceDetails are the components you need to connect to the Redux store. Take a look at the code there to familiarize yourself with it.

src/mockData/produce.json provides the mock data that you will use to populate the Redux store. The file has a JSON array of objects. Each object has the following structure:

{
  id: ID,
  name: String,
  liked: Boolean
}

In your preview of the code, make sure to understand how all the components connect (i.e., the parent-child relationships of all the components, the component tree).

npm install the following dependencies:

• redux - the Redux package
• react-redux - for connecting Redux to React

npm install -D the following dev-dependencies:

• redux-logger - a debugging tool for logging all actions dispatched

First thing you need to do is set up and configure the Redux store.

Create a folder called store inside of src. Inside of that folder, create a file called index.js. In this file, you will define the root reducer and a function that will return a Redux store.

Import createStore, combineReducers, applyMiddleware, and compose from redux.

// ./src/store/index.js
import { createStore, combineReducers, applyMiddleware, compose } from "redux";

• createStore - creates a Redux store
• combineReducers - creates one reducer from multiple reducers as slices of state
• applyMiddleware - a store enhancer that will allow you to attach middlewares (a middleware is a function called before any action hits the root reducer)
• compose - another store enhancer that will allow you to use more than one store enhancer

Next, define the rootReducer which will be the root reducer for the Redux store. The rootReducer will just be the return of combineReducers invoked with an empty object for now.

// ./src/store/index.js
// ...
const rootReducer = combineReducers({

});

Now, you are going to create a store enhancer that will be set only when your application is in development. When in development, you want to add the redux-logger middleware and the Redux dev tools extension store enhancer to your store. For redux-logger, you will use applyMiddleware, which returns a store enhancer. The store enhancer for the Redux dev tools extension is set by the extension to a global property, window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__. This store enhancer combines other store enhancers into one, just like compose from redux does.

Set the enhancer variable when in development to use these enhancers like so:

// ./src/store/index.js
// ...
let enhancer;

if (process.env.NODE_ENV !== "production") {
  const logger = require("redux-logger").default;
  const composeEnhancers =
    window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ || compose;
  enhancer = composeEnhancers(applyMiddleware(logger));
}

Let's break this down.

The logger variable is set to the default export of the imported redux-logger package using require instead of ES6 module imports. Why? ES6 module imports must be defined at the very top of the file in the outermost scope and will be loaded in all node environments. However, redux-logger is a development dependency and cannot be loaded in production. Loading it with require is needed if you only want it in a certain node environment.

The composeEnhancers variable is set to the Redux dev tools extension's store enhancer, window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ or the compose function from redux if the extension fails to load or if you don't have the extension installed in your browser.

The Redux compose function takes in store enhancers as its arguments and combines them to create a single store enhancer. The only other store enhancer that you need is the applyMiddleware invoked with the loaded logger. enhancer is set to the combined store enhancer.

Finally, define a function called configureStore that will take in a preloadedState and return the result of createStore invoked with the rootReducer, the preloadedState, and the enhancer. Export the configureStore function as the default export.

// ./src/store/index.js
// ...
const configureStore = (preloadedState) => {
  return createStore(rootReducer, preloadedState, enhancer);
};

export default configureStore;

Now, you need to wrap the React application with the Redux store provider.

Import the configureStore function into the entry file, src/index.js. Import the Provider component from react-redux.

Initialize a variable called store and set it to the return of configureStore (a preloadedState does not need to be passed in, it can be undefined).

In the Root function component, wrap the BrowserRouter component with the Provider component. Pass the prop of store with the value of store into the Provider.

Your entry file should look like this:

// ./src/index.js
import React from 'react';
import ReactDOM from 'react-dom';
import { BrowserRouter } from 'react-router-dom';
import { Provider } from 'react-redux';
import configureStore from './store';
import './index.css';
import App from './App';

const store = configureStore();

function Root() {
  return (
    <Provider store={store}>
      <BrowserRouter>
        <App />
      </BrowserRouter>
    </Provider>
  );
}

ReactDOM.render(
  <React.StrictMode>
    <Root />
  </React.StrictMode>,
  document.getElementById('root')
);

Let's test your setup!

Navigate to http://localhost:3000 and open up the browser's dev tools. In the console, you should see a message about an invalid reducer. That's because the rootReducer isn't combining any reducers yet. Ignore this warning for now.

Open the "Redux" tab in your browser's dev tools. You should not see the message "No store found".

In your entry file, expose the store variable on the window only in development for testing purposes.

// ./src/index.js
// ...
if (process.env.NODE_ENV !== "production") {
  window.store = store;
}

Navigate to http://localhost:3000 and refresh. You should see the store on the window in your browser's dev tools console. If you call store.getState() then you should just get back an empty object.

If you are having issues while testing, check your syntax in your store and entry files.

Commit your setup code!