Using Next.js's Server-side Rendering method

Just like the Static Generation, SSR (Server-side Rendering) is another way of data fetching supported in Next.js. The difference between SSR and SSG is that in SSR the data gets fetched for every request, while in SSG the data used to be fetched on build-time. This method is good for pages that have dynamic data, data that changes often.

When the user requests a SSR page, the server fetches the data (queries the DB, uses third-party APIs etc...), generates the HTML, and then gets it back to the browser. Compared to the SSG, the requests in SSR are slower, but that's the price to pay to have dynamic data.

To apply the SSR method in Next.js, we need to export a getServerSideProps method from our page:

1// pages/index.tsx
2
3import type { GetServerSideProps } from 'next'
4
5...
6
7export const getServerSideProps: GetServerSideProps<Props> = async (context) => {
8  return {
9    props: {
10      ...
11    }
12  }
13}

The context object is similar to SSG's context, but it also includes:

• req: the HTTP IncomingMessage object, plus additional parsing helpers
• res: the HTTP response object
• query: an object representing the query string

Unlike SSG, with SSR we don't need to provide a method similar to the getStaticPaths, because every request generates an HTML file, so no HTML files need to be generated at build-time.