Shiono Yoshihide

Posted on Oct 12, 2019

Learn the Redux Architecture by Creating the Minimal TODO App on top of NEXT.js

#react #redux #typescript #nextjs

In this article, I'll explain the React Redux architecture by creating so simple TODO app which has just only two features (ADD TODO and DELETE TODO).

This is a step by step guide of the example repo here:

saltyshiomix / nextjs-redux-todo-app

A minimal todo app with NEXT.js on the redux architecture

Features

Minimal but well structured
No CSS, only TypeScript
We can learn these stacks:
- next
- react
- redux and react-redux
- redux-thunk
- reselect
- recompose

Usage

# installation
$ git clone https://github.com/saltyshiomix/nextjs-todo-app.git
$ cd nextjs-todo-app
$ yarn (or `npm install`)

# development mode
$ yarn dev (or `npm run dev`)

# production mode
$ yarn build (or `npm run build`)
$ yarn start (or `npm start`)

View on GitHub

The Point of View

Minimal features
- Add TODO
- Delete TODO
Only TypeScript
- No database
- No CSS
We can learn these stacks:
- next
- react
- redux and react-redux
- redux-thunk
- reselect
- recompose

Folder Structures

NEXT.js Structures

.
├── components
│   ├── page.tsx
│   └── todo.tsx
├── next-env.d.ts
├── pages
│   ├── _app.tsx
│   └── index.tsx
└── tsconfig.json

Redux Structures

.
├── actions
│   └── index.ts
├── components
│   ├── page.tsx
│   └── todo.tsx
├── constants
│   └── actionTypes.ts
├── containers
│   └── page.tsx
├── reducers
│   ├── index.ts
│   └── todo.ts
├── selectors
│   └── index.ts
└── store.ts

Whole Structures

.
├── actions
│   └── index.ts
├── components
│   ├── page.tsx
│   └── todo.tsx
├── constants
│   └── actionTypes.ts
├── containers
│   └── page.tsx
├── next-env.d.ts
├── package.json
├── pages
│   ├── _app.tsx
│   └── index.tsx
├── reducers
│   ├── index.ts
│   └── todo.ts
├── selectors
│   └── index.ts
├── store.ts
└── tsconfig.json

Step 1: Hello World

$ mkdir test-app
$ cd test-app

After that, populate package.json and pages/index.tsx:

package.json

{
  "name": "test-app",
  "scripts": {
    "dev": "next"
  }
}

pages/index.tsx

export default () => <p>Hello World</p>;

And then, run the commands below:

# install dependencies
$ npm install --save next react react-dom
$ npm install --save-dev typescript @types/node @types/react @types/react-dom

# run as development mode
$ npm run dev

That's it!

Go to http://localhost:3000 and you'll see the Hello World!

Step 2: Build Redux TODO App (suddenly, I see)

I don't explain Redux architecture! lol

Just feel it, separation of the state and the view.

Define Features (ActionTypes and Actions)

Define the id of the action type in the constants/actionTypes.ts:

export const TODO_ONCHANGE = 'TODO_ONCHANGE';
export const TODO_ADD = 'TODO_ADD';
export const TODO_DELETE = 'TODO_DELETE';

And in the actions/index.ts, we define the callbacks to the reducers:

(Just define arguments and return data. Actions won't handle its state.)

import {
  TODO_ONCHANGE,
  TODO_ADD,
  TODO_DELETE,
} from '../constants/actionTypes';

export const onChangeTodo = (item) => ({ type: TODO_ONCHANGE, item });

export const addTodo = (item) => ({ type: TODO_ADD, item });

export const deleteTodo = (item) => ({ type: TODO_DELETE, item });

State Management (Reducers)

In the reducers/todo.ts, we define the initial state and how to handle it:

import {
  TODO_ONCHANGE,
  TODO_ADD,
  TODO_DELETE,
} from '../constants/actionTypes';

export const initialState = {
  // this is a TODO item which has one "value" property
  item: {
    value: '',
  },
  // this is a list of the TODO items
  data: [],
};

export default (state = initialState, action) => {
  // receive the type and item, which is defined in the `actions/index.ts`
  const {
    type,
    item,
  } = action;

  switch (type) {
    case TODO_ONCHANGE: {
      // BE CAREFUL!!!
      // DON'T USE THE REFERENCE LIKE THIS:
      //
      //     state.item = item;
      //     return state; // this `state` is "previous" state!
      //
      // Please create a new instance because that is a "next" state
      //
      return Object.assign({}, state, {
        item,
      });
    }

    case TODO_ADD: {
      // if the `item.value` is empty, return the "previous" state (skip)
      if (item.value === '') {
        return state;
      }

      return Object.assign({}, state, {
        // clear the `item.value`
        item: {
          value: '',
        },
        // create a new array instance and push the item
        data: [
          ...(state.data),
          item,
        ],
      });
    }

    case TODO_DELETE: {
      // don't use `state.data` directly
      const { data, ...restState } = state;

      // `[...data]` means a new instance of the `data` array
      // and filter them and remove the target TODO item
      const updated = [...data].filter(_item => _item.value !== item.value);

      return Object.assign({}, restState, {
        data: updated,
      });
    }

    // do nothing
    default: {
      return state;
    }
  }
};

And next, define reducers/index.ts which combines all reducers:

(currently only one reducer, yet)

import { combineReducers } from 'redux';
import todo, { initialState as todoState } from './todo';

export const initialState = {
  todo: todoState,
};

export default combineReducers({
  todo,
});

Create the Store

We define the one store so that we can access any states from the store.

And pass the store to the page: with the NEXT.js, pages/_app.tsx is one of the best choices.

store.ts

import thunkMiddleware from 'redux-thunk';
import {
  createStore,
  applyMiddleware,
  compose,
  Store as ReduxStore,
} from 'redux';
import { createLogger } from 'redux-logger';
import reducers, { initialState } from './reducers';

const dev: boolean = process.env.NODE_ENV !== 'production';

export type Store = ReduxStore<typeof initialState>;

export default (state = initialState): Store => {
  const middlewares = dev ? [thunkMiddleware, createLogger()] : [];
  return createStore(reducers, state, compose(applyMiddleware(...middlewares)));
};

pages/_app.tsx

import { NextPageContext } from 'next';
import App from 'next/app';
import withRedux from 'next-redux-wrapper';
import { Provider } from 'react-redux';
import store, { Store } from '../store';

interface AppContext extends NextPageContext {
  store: Store;
}

class MyApp extends App<AppContext> {
  render() {
    const { store, Component, ...props } = this.props;
    return (
      <Provider store={store}>
        <Component {...props} />
      </Provider>
    );
  }
}

export default withRedux(store)(MyApp);

Compose the Pages

First, define selectors to avoid deep nested state:

import { createSelector } from 'reselect';

export const selectState = () => state => state.todo;

export const selectTodoItem = () =>
  createSelector(
    selectState(),
    todo => todo.item,
  );

export const selectTodoData = () =>
  createSelector(
    selectState(),
    todo => todo.data,
  );

Second, use that selectors and pass them to the container with the actions:

containers/page.ts

import { connect } from 'react-redux';
import { createSelector } from 'reselect';
import {
  compose,
  pure,
} from 'recompose';
import {
  onChangeTodo,
  addTodo,
  deleteTodo,
} from '../actions';
import {
  selectTodoItem,
  selectTodoData,
} from '../selectors';
import Page from '../components/page';

export default compose(
  connect(
    createSelector(
      selectTodoItem(),
      selectTodoData(),
      (item, data) => ({ item, data }),
    ),
    {
      onChangeTodo,
      addTodo,
      deleteTodo,
    },
  ),
  pure,
)(Page);

Third, implement the page component:

components/page.tsx

import React from 'react';
import { compose } from 'recompose';
import Todo from './todo';

const Page = (props) => {
  // defined in the `containers/page.ts`, so the `props` is like this:
  //
  // const {
  //   item,
  //   data,
  //   onChangeTodo,
  //   addTodo,
  //   deleteTodo,
  // } = props;
  //
  return <Todo {...props} />;
};

export default compose()(Page);

Implement components/todo.tsx:

import React from 'react';
import { compose } from 'recompose';

const Todo= (props) => {
  const {
    item,
    data,
    onChangeTodo,
    addTodo,
    deleteTodo,
  } = props;

  return (
    <React.Fragment>
      <h1>TODO</h1>
      <form onSubmit={(e) => {
        e.preventDefault();
        addTodo({
          value: item.value,
        });
      }}>
        <input
          type="text"
          value={item.value}
          onChange={e => onChangeTodo({
            value: e.target.value,
          })}
        />
        <br />
        <input
          type="submit"
          value="SUBMIT"
          style={{
            display: 'none',
          }}
        />
      </form>
      <hr />
      {data.map((item, index) => (
        <p key={index}>
          {item.value}
          {' '}
          <button onClick={() => deleteTodo(item)}>
            DELETE
          </button>
        </p>
      ))}
    </React.Fragment>
  );
};

export default compose()(Todo);

Rewrite `pages/index.tsx`

Finally, update pages/index.tsx like this:

import {
  NextPageContext,
  NextComponentType,
} from 'next';
import { compose } from 'recompose';
import { connect } from 'react-redux';
import Page from '../containers/page';
import { addTodo } from '../actions';
import { Store } from '../store';

interface IndexPageContext extends NextPageContext {
  store: Store;
}

const IndexPage: NextComponentType<IndexPageContext> = compose()(Page);

IndexPage.getInitialProps = ({ store, req }) => {
  const isServer: boolean = !!req;

  // we can add any custom data here
  const { todo } = store.getState();
  store.dispatch(addTodo(Object.assign(todo.item, {
    value: 'Hello World!',
  })));

  return {
    isServer,
  };
}

export default connect()(IndexPage);

`TODO_ONCHANGE`:

`TODO_ADD`:

`TODO_DELETE`:

Conclusion

Practice makes perfect.

Thank you for your reading!

Top comments (8)

Jatto Abdulqahhar • Nov 23 '19

Hi, Nice article. Thank you.

I would like to use redux dev tools with this in development, but I am finding it difficult to setup.
Here is the link to the tool documentation. github.com/zalmoxisus/redux-devtoo...

Can you help take a look?

Jatto Abdulqahhar • Nov 23 '19

Thanks, I have figured this out.

What I did!

Added the 'redux-devtools-extension' package (yarn add redux-devtools-extension)
Import the composeWithDevTools (import { composeWithDevTools } from 'redux-devtools-extension';)
Create a composeEnhancers (const composeEnhancers = composeWithDevTools({});)
wrap the applyMiddleware function with the composeEnhancers Function (composeEnhancers(applyMiddleware(...middlewares)))

Update Store.ts file

import thunkMiddleware from 'redux-thunk';
import {
  createStore,
  applyMiddleware,
  Store as ReduxStore,
} from 'redux';
import { createLogger } from 'redux-logger';
import { composeWithDevTools } from 'redux-devtools-extension';
import reducers, { initialState } from './reducers';

const dev: boolean = process.env.NODE_ENV !== 'production';

export type Store = ReduxStore<typeof initialState>;

const composeEnhancers = composeWithDevTools({});

export default (state = initialState): Store => {
  const middlewares = dev ? [thunkMiddleware, createLogger()] : [];
  return createStore(
    reducers,
    state,
    composeEnhancers(applyMiddleware(...middlewares))
  );
};

Shiono Yoshihide • Nov 24 '19

Yes, you have done right!

Or just replace compose with composeWithDevtools like this commit:

const { composeWithDevTools } = dev ? require('redux-devtools-extension') : require('redux-devtools-extension/logOnlyInProduction');

export default (state = initialState): Store => {
  const middlewares = dev ? [thunkMiddleware, createLogger()] : [];
  return createStore(reducers, state, composeWithDevTools(applyMiddleware(...middlewares)));
};

Jatto Abdulqahhar • Nov 24 '19

Thanks, Do you have an idea of how to include SCSS to this setup?

Shiono Yoshihide • Nov 24 '19

This is a NEXT.js side.
Please see github.com/zeit/next.js/tree/canar...

Mykezero • Oct 12 '19 • Edited

Heard nextjs and redux: will try later tonight. Sounds like a lot of fun! Thanks for posting this!! ^^

Shiono Yoshihide • Oct 13 '19

Thank you for your comment!

If you have any advices, feel free to contact me :)

Muco Rolle Tresor • Jan 25 '20

thanks this was so helpfull

DEV Community

Learn the Redux Architecture by Creating the Minimal TODO App on top of NEXT.js

saltyshiomix / nextjs-redux-todo-app

A minimal todo app with NEXT.js on the redux architecture

Features

Usage

The Point of View

Folder Structures

NEXT.js Structures

Redux Structures

Whole Structures

Step 1: Hello World

Step 2: Build Redux TODO App (suddenly, I see)

Define Features (ActionTypes and Actions)

State Management (Reducers)

Create the Store

Compose the Pages

Rewrite `pages/index.tsx`

`TODO_ONCHANGE`:

`TODO_ADD`:

`TODO_DELETE`:

Conclusion

Top comments (8)

Update Store.ts file

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Building an Authentication Wrapper in React/Next.js + GraphQL 💪

Unwrapping JavaScript ES2024: Key Features Every Developer Should Know

Find your Location With Javascript

Advanced State Management in React

saltyshiomix / nextjs-redux-todo-app

A minimal todo app with NEXT.js on the redux architecture

Features

Usage

The Point of View

Folder Structures

NEXT.js Structures

Redux Structures

Whole Structures

Step 1: Hello World

Step 2: Build Redux TODO App (suddenly, I see)

Define Features (ActionTypes and Actions)

State Management (Reducers)

Create the Store

Compose the Pages

Rewrite pages/index.tsx

TODO_ONCHANGE:

TODO_ADD:

TODO_DELETE:

Conclusion

Update Store.ts file

Read next

Building an Authentication Wrapper in React/Next.js + GraphQL 💪

Unwrapping JavaScript ES2024: Key Features Every Developer Should Know

Find your Location With Javascript

Advanced State Management in React

Rewrite `pages/index.tsx`

`TODO_ONCHANGE`:

`TODO_ADD`:

`TODO_DELETE`: