Build an API for your front end using Pages Functions

In this tutorial, you will build a full-stack Pages application. Your application will contain:

• A front end, built using Cloudflare Pages and the React framework.
• A JSON API, built with Pages Functions, that returns blog posts that can be retrieved and rendered in your front end.

If you prefer to work with a headless CMS rather than an API to render your blog content, refer to the headless CMS tutorial.

​​ Build your front end

To begin, create a new Pages application using the React framework.

​​ Create a new React project

In your terminal, create a new React project called blog-frontend using the create-react-app command. Go into the newly created blog-frontend directory and start a local development server:

Create a new React application
$ npx create-react-app blog-frontend
$ cd blog-frontend
$ npm start

​​ Set up your React project

To set up your React project:

1. Install the React Router Open external link in the root of your blog-frontend directory.

With npm:

$ npm install react-router-dom@6

With yarn:

$ yarn add react-router-dom@6

2. Clear the contents of src/App.js. Copy and paste the following code to import the React Router into App.js, and set up a new router with two routes:

src/App.js
import { Routes, Route } from 'react-router-dom';

import Posts from './components/posts';
import Post from './components/post';

function App() {
  return (
    <Routes>
      <Route path="/" element={<Posts />} />
      <Route path="/posts/:id" element={<Post />} />
    </Routes>
  );
}

export default App;

3. In the src directory, create a new folder called components.
4. In the components directory, create two files: posts.js, and post.js. These files will load the blog posts from your API, and render them.
5. Populate posts.js with the following code:

src/components/posts.js
import React, { useEffect, useState } from 'react';
import { Link } from "react-router-dom";

const Posts = () => {
    const [posts, setPosts] = useState([]);

    useEffect(() => {
        const getPosts = async () => {
            const resp = await fetch('/api/posts');
            const postsResp = await resp.json();
            setPosts(postsResp);
        };

        getPosts();
    }, []);

    return (
        <div>
            <h1>Posts</h1>
            {posts.map(post => (
                <div key={post.id}>
                    <h2>
                        <Link to={`/posts/${post.id}`}>{post.title}</Link>
                    </h2>
                </div>
            ))}
        </div>
    );
};

export default Posts;

6. Populate post.js with the following code:

src/components/post.js
import React, { useEffect, useState } from 'react';
import { Link, useParams } from 'react-router-dom';

const Post = () => {
    const [post, setPost] = useState({});
    const { id } = useParams();

    useEffect(() => {
        const getPost = async () => {
            const resp = await fetch(`/api/post/${id}`);
            const postResp = await resp.json();
            setPost(postResp);
        };

        getPost();
    }, [id]);

    if (!Object.keys(post).length) return <div />;

    return (
        <div>
            <h1>{post.title}</h1>
            <p>{post.text}</p>
            <p>
                <em>Published {new Date(post.published_at).toLocaleString()}</em>
            </p>
            <p>
                <Link to="/">Go back</Link>
            </p>
        </div>
    );
};

export default Post;

​​ Build your API

You will now create a Pages Functions that stores your blog content and retrieves it via a JSON API.

​​ Write your Pages Function

To create the Pages Function that will act as your JSON API:

1. Create a functions directory in your blog-frontend directory.
2. In functions, create a directory named api.
3. In api, create a posts.js file in the api directory.
4. Populate posts.js with the following code:

functions/api/posts.js
import posts from './post/data'

export function onRequestGet() {
    return Response.json(posts)
}

This code gets blog data (from data.js, which you will make in step 8) and returns it as a JSON response from the path /api/posts.

5. In the api directory, create a directory named post.
6. In the post directory, create a data.js file.
7. Populate data.js with the following code. This is where your blog content, blog title, and other information about your blog lives.

functions/api/post/data.js
const posts = [
    {
        id: 1,
        title: 'My first blog post',
        text: 'Hello world! This is my first blog post on my new Cloudflare Workers + Pages blog.',
        published_at: new Date('2020-10-23'),
    },
    {
        id: 2,
        title: 'Updating my blog',
        text: "It's my second blog post! I'm still writing and publishing using Cloudflare Workers + Pages :)",
        published_at: new Date('2020-10-26'),
    },
];

export default posts

8. In the post directory, create an [[id]].js file.
9. Populate [[id]].js with the following code:

[[id]].js
import posts from './data'

export function onRequestGet(context) {
    const id = context.params.id

    if (!id) {
        return new Response('Not found', { status: 404 })
    }

    const post = posts.find(post => post.id === Number(id))

    if (!post) {
        return new Response('Not found', { status: 404 })
    }

    return Response.json(post)
}

[[id]].js is a dynamic route which is used to accept a blog post id.

​​ Deploy

After you have configured your Pages application and Pages Function, deploy your project using the Wrangler or via the dashboard.

​​ Deploy with Wrangler

In your blog-frontend directory, run wrangler pages deploy to deploy your project to the Cloudflare dashboard.

$ wrangler pages deploy blog-frontend

​​ Deploy via the dashboard

To deploy via the Cloudflare dashboard, you will need to create a new Git repository for your Pages project and connect your Git repository to Cloudflare. This tutorial uses GitHub as its Git provider.

​​ Create a new repository

Create a new GitHub repository by visiting repo.new Open external link . After creating a new repository, prepare and push your local application to GitHub by running the following commands in your terminal:

$ git init
$ git remote add origin https://github.com/<YOUR-GH-USERNAME>/<REPOSITORY-NAME>
$ git add .
$ git commit -m "Initial commit"
$ git branch -M main
$ git push -u origin main

​​ Deploy with Cloudflare Pages

Deploy your application to Pages:

1. Log in to the Cloudflare dashboard Open external link and select your account.
2. In Account Home, select Workers & Pages > Create application > Pages > Connect to Git.
3. Select the new GitHub repository that you created and, in the Set up builds and deployments section, provide the following information:

After configuring your site, begin your first deploy. You should see Cloudflare Pages installing blog-frontend, your project dependencies, and building your site.

By completing this tutorial, you have created a full-stack Pages application.

​​ Related resources

• Learn about Pages Functions routing