What is the relationship between getStaticPaths and getStaticProps in Next.js?

In Next.js, getStaticPaths and getStaticProps are two functions used for server-side rendering (SSR) and static site generation (SSG) to pre-render pages.

• getStaticPaths:

  • The getStaticPaths function is used to specify dynamic routes that should be pre-rendered to HTML at build time.
  • It is typically used with dynamic routes where the number of possible paths is not known in advance, such as pages that depend on data fetched from an external API or a database.
  • getStaticPaths returns an object containing two keys:
    • paths: An array of possible values for the dynamic segments in the URL.
    • fallback: A boolean value indicating whether to show a fallback page (404 page) for paths that have not been generated at build time.

• getStaticProps:

  • The getStaticProps function is used to fetch data at build time and pre-render a page with that data.
  • It allows you to fetch data from any data source, including APIs, databases, or files.
  • The data returned from getStaticProps is serialized to JSON before being sent to the component as props.
  • getStaticProps is a per-page function, meaning that it's exported from a page (or a component) and not from a regular utility file.

Relationship:

• getStaticPaths and getStaticProps are often used together in Next.js when dealing with dynamic routes.
• getStaticPaths determines the possible values for the dynamic parameters in the URL, while getStaticProps fetches the necessary data for each possible value.
• getStaticPaths is required when using getStaticProps with dynamic routes. It tells Next.js which paths it needs to pre-render.
• The values returned by getStaticPaths are used to determine which pages Next.js will statically generate at build time.
• getStaticProps is then called for each path returned by getStaticPaths to fetch the necessary data and pre-render the page.

In summary, getStaticPaths sets the paths that Next.js should pre-render, while getStaticProps fetches the data for each path during the pre-rendering process.