RTK Query is a powerful data fetching and caching tool that is part of the Redux Toolkit package. It lets you define your API endpoints as functions, and then automatically generates React hooks to fetch and update data from those endpoints. It also handles loading states, caching, invalidation, and more. 🙌

In this blog, you will learn how to use RTK Query in a Next.js app. You will see how easy it is to set up your store and API service, how to use the generated hooks in your components, and how to customize your queries and mutations. 💯

By the end of this blog, you will be able to use RTK Query in your own Next.js projects and enjoy the benefits of data fetching and caching done right. 🔥

So, are you ready to learn more about RTK Query? Let's get started! 😊

You can Check the Code Here: https://github.com/Subham-Maity/rtk_query

1. Syntax Check out the docs

// Import the createApi and fetchBaseQuery functions from the RTK Query library
import {createApi, fetchBaseQuery} from "@reduxjs/toolkit/query/react";

// Create an API service using the createApi function
export const productsAPI = createApi({
    // Specify a unique name for the API slice in the Redux store
    reducerPath: "productsAPI",
    // Specify a base query function that will be used to make network requests
    // In this case, we use the fetchBaseQuery function that is a wrapper around the native fetch API
    baseQuery: fetchBaseQuery({
        // Specify the base URL for the API endpoints
        baseUrl: "",
    }),
    // Define the endpoints for the API service using a builder callback
    // The builder provides methods for defining query and mutation endpoints
    endpoints: (builder) => ({}),
});

// Export the auto-generated hooks for the defined endpoints
// The hooks allow us to easily perform queries and mutations in our React components
export const {} = productsAPI;

1. Inside the endpoints callback, we can define our endpoints using the builder object. The builder object provides methods for defining query and mutation endpoints.

//here getProductByName is the name of the endpoint and builder.query is the method to define query endpoints and query is the callback function that will be called when the endpoint is used.
getProductByName: builder.query({
    query: () => ``,
})

//here useGetProductByNameQuery is the name of the hook that will be used to call the endpoint 
// syntax: use + endpoint name(First letter capital) + Query
export const {useGetProductByNameQuery} = productsAPI;

final

import {createApi, fetchBaseQuery} from "@reduxjs/toolkit/query/react";

export const productsAPI = createApi({
    reducerPath: "productsAPI",
    baseQuery: fetchBaseQuery({
        baseUrl: "",
    }),
    endpoints: (builder) => ({
        getProductByName: builder.query({
            query: () => ``,
        }),
    }),
});

export const {useGetProductByNameQuery} = productsAPI;

1. Define the base URL for the API endpoints

//this will be the base url for the endpoints
baseUrl: "https://jsonplaceholder.typicode.com"

//This will be the endpoint
query: () => `users`

final

import {createApi, fetchBaseQuery} from "@reduxjs/toolkit/query/react";

export const productsAPI = createApi({
    reducerPath: "productsAPI",
    baseQuery: fetchBaseQuery({
        baseUrl: "https://jsonplaceholder.typicode.com",
    }),
    endpoints: (builder) => ({
        getProductByName: builder.query({
            query: () => `users`,
        }),
    }),
});

export const {useGetProductByNameQuery} = productsAPI;

1. Create store and use it in the provider then wrap the layout with the provider

import {configureStore} from "@reduxjs/toolkit";

export const store = configureStore({
    reducer: {},
});

ReduxProvider.tsx

"use client";
import React from "react";

import {store} from "../store";
/* Core */
import {Provider} from "react-redux";

/* Instruments */

export const ReduxProvider = (props: React.PropsWithChildren) => {
    return <Provider store={store}>{props.children}</Provider>;
};

Layout.tsx

import "./globals.css";
import type {Metadata} from "next";
import {Inter} from "next/font/google";
import React from "react";
import {ReduxProvider} from "@/redux/Provider/ReduxProvider";

const inter = Inter({subsets: ["latin"]});

export const metadata: Metadata = {
    title: "Create Next App",
    description: "Generated by create next app",
};

export default function RootLayout({
                                       children,
                                   }: {
    children: React.ReactNode;
}) {
    return (
        <html lang="en">
        <ReduxProvider>
            <body className={inter.className}>{children}</body>
        </ReduxProvider>
        </html>
    );
}

1. Inside the store reducer add the api reducer

//Generate the reducer as a specific top-level key in the store
[productsAPI.reducerPath]
:
productsAPI.reducer

final

//store.ts
import {configureStore} from "@reduxjs/toolkit";
import {productsAPI} from "@/redux/slice/api";

export const store = configureStore({
    reducer: {
        [productsAPI.reducerPath]: productsAPI.reducer,
    },
});

1. After the reducer use the middleware

// Adding the api middleware enables caching, invalidation, polling,and other useful features of `rtk-query`.
middleware: (getDefaultMiddleware) =>
    getDefaultMiddleware().concat(productsAPI.middleware)

setupListeners(store.dispatch);

// takes an optional callback as the 2nd arg for customization
setupListeners(store.dispatch);

final

//store.ts
import {configureStore} from "@reduxjs/toolkit";
import {productsAPI} from "@/redux/slice/api";

export const store = configureStore({
    reducer: {
        [productsAPI.reducerPath]: productsAPI.reducer,
    },
    middleware: (getDefaultMiddleware) =>
        getDefaultMiddleware().concat(productsAPI.middleware),
});
setupListeners(store.dispatch);

1. Now we can use the hook in our component

Open page.tsx

//Once a service has been defined, you can import the hooks to make a request.
const data = useGetProductByNameQuery("");
console.log(data);

Now destruct the data and use it in the component

const {data} = useGetProductByNameQuery("");
console.log(data);

You can see the data in the console of the browser page.tsx

"use client";

import {useGetProductByNameQuery} from "@/redux/slice/api";

export default function Home() {
    const {data} = useGetProductByNameQuery("");

    return (
        <main>
            <h1>Home</h1>
            <p>rtk-query data: {JSON.stringify(data)}</p>
        </main>
    );
}

1. Now you can iterate over the data and show it in the component

make a type.ts

// types.ts
export interface UserData {
    id: number;
    name: string;
    username: string;
    email: string;
    address: {
        street: string;
        suite: string;
        city: string;
        zipcode: string;
        geo: {
            lat: string;
            lng: string;
        };
    };
    phone: string;
    website: string;
    company: {
        name: string;
        catchPhrase: string;
        bs: string;
    };
}

"use client";

import {useGetProductByNameQuery} from "@/redux/slice/api";
import {UserData} from "@/app/types";

export default function Home() {
    const {data} = useGetProductByNameQuery("");
    //usually happens when the API call hasn't finished fetching the data yet
    //To resolve this issue, you need to ensure that you're handling the loading state correctly. One way to do this is by checking whether the data is present before trying to map over it. 
    if (!data) {
        return <div>Loading...</div>;
    }
    return (
        <div>
            {data.map((item: UserData) => (
                <div key={item.id}>
                    <h2>{item.name}</h2>
                    <p>{item.email}</p>
                    <p>{item.company.catchPhrase}</p>
                    <p>{item.address.city}</p>
                </div>
            ))}
        </div>);
}

Check out the preview here

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Thank you for reading this blog and stay tuned for more. If you have any questions or feedback, feel free to leave a comment below or contact me directly. I would love to hear from you. 🙌

If you are looking for a freelance web developer who can help you with your projects, you can also contact me. I have experience in working with Next.js, RTK Query, and other modern web technologies. I can help you build fast, scalable, and user-friendly web applications. 💯

You can reach me by sending an email to codexam.personal@gmail.com or by filling out this [contact form]. I will get back to you as soon as possible. 😊

I look forward to hearing from you and collaborating with you on your projects. 🙌

Until next time, happy coding! 👋