Pre-rendering and Data Fetching

Implement getStaticProps

First, install gray-matter which lets us parse the metadata in each markdown file.

npm install gray-matter

Next, we’ll create a simple library for fetching data from the file system.

  • Create a top-level directory called lib, and…
  • Create a file called posts.js inside with the following contents:
import fs from 'fs'
import path from 'path'
import matter from 'gray-matter'

const postsDirectory = path.join(process.cwd(), 'posts')

export function getSortedPostsData() {
  // Get file names under /posts
  const fileNames = fs.readdirSync(postsDirectory)
  const allPostsData = => {
    // Remove ".md" from file name to get id
    const id = fileName.replace(/\.md$/, '')

    // Read markdown file as string
    const fullPath = path.join(postsDirectory, fileName)
    const fileContents = fs.readFileSync(fullPath, 'utf8')

    // Use gray-matter to parse the post metadata section
    const matterResult = matter(fileContents)

    // Combine the data with the id
    return {
  // Sort posts by date
  return allPostsData.sort((a, b) => {
    if ( < {
      return 1
    } else {
      return -1

Now, let's import getSortedPostsData inside pages/index.js:

import { getSortedPostsData } from '../lib/posts'

Then, add getStaticProps to pages/index.js and call getSortedPostsData inside.

export async function getStaticProps() {
  const allPostsData = getSortedPostsData()
  return {
    props: {

By returning allPostsData inside the props object, the blog posts will be passed to the Home component. To see this, modify the component definition to take { allPostsData }:

export default function Home ({ allPostsData }) { ... }

To display the data, add another <section> tag at the bottom of this component:

export default function Home({ allPostsData }) {
  return (
    <Layout home>
      <section className={utilStyles.headingMd}></section>
      <section className={`${utilStyles.headingMd} ${utilStyles.padding1px}`}>
        <h2 className={utilStyles.headingLg}>Blog</h2>
        <ul className={utilStyles.list}>
          {{ id, date, title }) => (
            <li className={utilStyles.listItem} key={id}>
              <br />
              <br />

You should now see the blog data if you access http://localhost:3000.

Congratulations! We’ve successfully fetched external data (from the file system) and pre-rendered the index page with this data.

Let’s talk about some tips for using getStaticProps on the next page.