Normalizing State with createEntityAdapter in React Redux

Last Updated on May 2, 2022 by Pupli

We can read how to “normalize” state from here, but simply we can do it  by keeping items in an object keyed by item IDs. This gives us the ability to look up any item by its ID without having to loop through an entire array. However, writing the logic to update normalized state by hand was long and tedious. Writing “mutating” update code with Immer makes that simpler, but there’s still likely to be a lot of repetition – we might be loading many different types of items in our app, and we’d have to repeat the same reducer logic each time.

Redux Toolkit includes a createEntityAdapter API that has prebuilt reducers for typical data update operations with normalized state. This includes adding, updating, and removing items from a slice. createEntityAdapter also generates some memoized selectors for reading values from the store.

createEntityAdapter is a function that generates a set of prebuilt reducers and selectors for performing CRUD operations on a normalized state structure containing instances of a particular type of data object. These reducer functions may be passed as case reducers to createReducer and createSlice. They may also be used as “mutating” helper functions inside of createReducer and createSlice.


import {createEntityAdapter, createSlice} from "@reduxjs/toolkit";
import {RootState} from "../../app/store";

export type BookState = { bookId: number, bookTitle: string, };

const booksAdapter = createEntityAdapter<BookState>({
    selectId: model => model.bookId,
    sortComparer: (a, b) => a.bookTitle.localeCompare(b.bookTitle),

export const booksSlice = createSlice({
    name: "books",
    initialState: booksAdapter.getInitialState,
    reducers: {
        addOne: booksAdapter.addOne,

export const booksActions = booksSlice.actions;
export const booksSelectors = booksAdapter.getSelectors<RootState>(
    (state) => state.books

export default booksSlice.reducer;


import {useAppSelector, useAppDispatch} from '../../app/hooks';
import {BookState, booksActions, booksSelectors} from "./booksSlice";
import {useState} from "react";

function Books() {

    const dispatch = useAppDispatch();
    const books = useAppSelector(booksSelectors.selectAll);
    const [bookTitle, setBookTitle] = useState("");

    const addHandler = () => {
        const newBook: BookState = {
            bookId: Math.floor(Math.random() * 1000),
            bookTitle: bookTitle

    return (

            <div className="mx-2 my-2">
                <input type="text" placeholder="Books Title" className="input input-bordered w-full max-w-xs"
                       value={bookTitle} onChange={event => setBookTitle(}/>
                <button className="btn mx-2" onClick={addHandler}>Add</button>

                {, index) => (
                    <li key={value.bookId}>Title : {value.bookTitle}, Id : {value.bookId}</li>

export default Books;