RSS Feed with Next.js

A good blog needs an RSS feed, even if hardly anyone seems to use an RSS reader anymore.
This article will explain how to create a RSS feed for a static blog.
In this example we will use contentlayer,
but it should work with other data sources too.

Feed generator

First we need a script to create the feed from our posts.
The script will load the generated posts from the contentlayer directory.

import { allPosts } from "../.contentlayer/generated/index.mjs";

I had to specify the whole path including the extension, otherwise node threw errors at me.

After that we use the feed library to create the feed and
to convert our posts into RSS items.
First we have to install the library and install date-fns as well.
We need date-fns later to simplify working with dates.

pnpm add -D feed date-fns

# or with yarn
yarn add -D feed date-fns

# or with npm
npm install --save-dev feed date-fns

Than we can create the feed and specify some information about our blog e.g.:

• title
• description
• url
• language

This could look as follows.

import { Feed } from "feed";

const feed = new Feed({
  title: "Example blog",
  description: "Description for the awesome example blog",
  id: "https://blog.example.com",
  link: "https://blog.example.com",
  language: "en",
  favicon: "https://blog.example.com/favicon.ico",
  copyright: "All rights reserved 2022, Your Name",
  author: {
    name: "Your Name",
    email: "[e-mail]",
    link: "https://blog.example.com",
  },
});

Now we can convert our blog posts to feed items.
We start by sorting the posts by their date.
Then we convert each post to a RSS item and add it to the feed.

import { compareDesc, parseISO } from "date-fns";

allPosts
  .sort((a, b) => compareDesc(new Date(a.date), new Date(b.date)))
  .forEach((post) => {
    const url = `https://example.com/posts/${post._raw.flattenedPath}`;
    feed.addItem({
      id: url,
      link: url,
      title: post.title,
      description: post.summary,
      date: parseISO(post.date),
      category: post.tags.map((name) => ({ name })),
      image: post.coverImage,
      author: [{
        name: "Your Name",
        email: "[e-mail]",
        link: "https://blog.example.com",
      }],
    });
  });

The feed does not contain the content of our posts. If we want to include the content we can attach it as HTML.
Now we should have everything in place and we can write the feed to the public directory:

import { writeFileSync } from "fs";

writeFileSync("./public/rss.xml", feed.rss2(), { encoding: "utf-8" })

The complete script should like the following.

import { compareDesc, parseISO } from "date-fns";
import { Feed } from "feed";
import { writeFileSync } from "fs";
import { allPosts } from "../.contentlayer/generated/index.mjs";

const feed = new Feed({
  title: "Example blog",
  description: "Description for the awesome example blog",
  id: "https://blog.example.com",
  link: "https://blog.example.com",
  language: "en",
  favicon: "https://blog.example.com/favicon.ico",
  copyright: "All rights reserved 2022, Your Name",
  author: {
    name: "Your Name",
    email: "[e-mail]",
    link: "https://blog.example.com",
  },
});

allPosts
  .sort((a, b) => compareDesc(new Date(a.date), new Date(b.date)))
  .forEach((post) => {
    const url = `https://example.com/posts/${post._raw.flattenedPath}`;
    feed.addItem({
      id: url,
      link: url,
      title: post.title,
      description: post.summary,
      date: parseISO(post.date),
      category: post.tags.map((name) => ({ name })),
      image: post.coverImage,
      author: [{
        name: "Your Name",
        email: "[e-mail]",
        link: "https://blog.example.com",
      }],
    });
  });

writeFileSync("./public/rss.xml", feed.rss2(), { encoding: "utf-8" });

Discoverability

In order for RSS readers to find our feed, we can help them with a link tag in the head of our page.
For Next.js 13 and the app directory, the root layout is the right place for the link tag, since that is how it's included in every page.

import { FC, PropsWithChildren } from "react";

const RootLayout: FC<PropsWithChildren> = ({ children }) => (
  <html lang="en">
    <head>
      <link rel="alternate" type="application/rss+xml" title="example.com rss feed" href="/rss.xml" />
    </head>
    <body>{children}</body>
  </html>
);

export default RootLayout;

Build

Now it's time to add our feed generator to the build:

{
  "scripts": {
    "build": "next build && node scripts/rss.mjs"
  }
}

Whenever our page is build using the build script, our RSS feed gets build afterwards.
The order is important, because contentlayer have to run first in order to generate the posts.

Git

Because our RSS feed is generated, we should exclude it from our repository:

/node_modules
/.next/
.contentlayer
public/rss.xml

If we would not do that, we would see changes to the rss.xml every time we work on our posts.