Redux to a Next JS App

First set up your next js application

yarn create next-app next-redux

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Next we install the desired packages

yarn add redux redux-thunk next-redux-wrapper react-redux

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After that installation, create a redux folder in the root of your project, inside that folder add a types.js and store.js files, also add folders for actions and reducers.

In the types file, lets add a single type; for setting the name of the user

export const SET_NAME = "SET_NAME"

In the reducers folder, add a main.js file, In this file we will create a reducer that will manage the main state of our app.

In this file we will initialize a main state with only one value for the name that defaults to guest. Then we will use a switch statement to detect the passed in action and value, the state gets updated based on the value received.

import * as t from "../types";

const main = (state = {
    name: "guest",
}, action) => {
  switch(action.type){
    case t.SET_NAME:
      return { 
        ...state,
        name: action.payload
      };
    default:
      return {...state};
    }
}

export default main;

In the same reducers folder, we will add a rootReducer.js file, this file will combine all our reducers into one, it is most useful when you have multiple reducer files, for this article i will only be using a single reducer file, which is my main reducer.

import { combineReducers } from "redux"
import main from "./main"

const rootReducer = combineReducers({
  main: main
})

export default rootReducer;

Next, we move to our store.js file

In this file we will create our redux store using redux and next-redux-wrapper, we will also add redux-thunk to allow us have extra functions before dispatching new values to our state.

import { createStore, applyMiddleware, compose } from "redux"
import thunk from "redux-thunk"
import { createWrapper } from "next-redux-wrapper"
import rootReducer from "./reducers/rootReducer"

const middleware = [thunk]

const makeStore = () => createStore(rootReducer, compose(applyMiddleware(...middleware)))

export const wrapper = createWrapper(makeStore)

Now we will create our set name action, create a main.js file in the actions folder, inside it we will have a function that specifies the set name type with a new name value.

import * as t from "../types";
import axios from "axios";
import { request } from "../../util/request";

export const setInfo = (name) => dispatch => {
  dispatch({
    type: t.SET_NAME,
    payload: name
  });
}

Now move to your _app.js file, it should look like;

import '../styles/globals.css'

function MyApp({ Component, pageProps }) {
  return <Component {...pageProps} />
}

export default MyApp

Update it to look like;

import React from "react"
import { wrapper } from "../redux/store"

const MyApp = ({ Component, pageProps}) => (
  <Component {...pageProps} />
)

export default wrapper.withRedux(MyApp);

We’ve wrapped the app in the redux wrapper we created in our store file and passed props to it.
In our index.js, take out all the page content and leave an input box asking for a name.

return (
    <div className={styles.container}>
      <p>Enter a Name :</p>
      <input 
        type="text">

        </input>
        <button>
          Submit
        </button>
    </div>
  )

Next we add some state management for updating and storing the value of our form using useState, we also link our index page to our redux state and finally connect the actions using mapDispatchToProps and the state using mapStateToProps, the final index.js should look like below

import { useState } from 'react'
import { connect } from "react-redux"
import { setInfo } from "../redux/actions/main"
import styles from '../styles/Home.module.css'

function Home(props) {
  const { name, setInfo } = props
  const [newName, setName] = useState("")

  return (
    <div className={styles.container}>
      <p>Enter a Name {name}:</p>
      <input 
        type="text" 
        value={newName} 
        onChange={(e) => setName(e.target.value)}>

        </input>
        <button onClick={() => setInfo(newName)}>
          Submit
        </button>
    </div>
  )
}

const mapStateToProps = state => {
 return { name: state.main.name }
}

const mapDispatchToProps = {
  setInfo
}

export default connect(mapStateToProps, mapDispatchToProps)(Home)

To be able to debug with Redux Dev Tools, update your store.js code to;

import { createStore, applyMiddleware, compose } from "redux"
import thunk from "redux-thunk"
import { createWrapper } from "next-redux-wrapper"
import rootReducer from "./reducers/rootReducer"

const middleware = [thunk]

const composeEnhancers =
  typeof window === 'object' &&
  window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ ?   
    window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__({}) : compose;

const enhancer = composeEnhancers(applyMiddleware(...middleware));

const makeStore = () => createStore(rootReducer, enhancer)

export const wrapper = createWrapper(makeStore)

Your home page should now look like the below image, and changing the name should update the value of “guest”.

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