context.req is missing in getStaticProps

Feature request

Is your feature request related to a problem? Please describe.

For my website I’ve built up some APIs via /pages/api for the various data fetching needs that my application has. Sometimes I want to hit those endpoints via the client, and other times via the server, and often at build time using getStaticProps. Unfortunately, at the moment I cannot call those API methods from the getStaticProps method.

My initial instinct was to try:

export const getStaticProps = async () => {
    const data = await fetch('/api/mydata');
}

But that gives me TypeError: Only absolute URLs are supported. It makes sense because you must provide a hostname to fetch() when it’s run at build time. How do I give it the hostname of whatever the current server is (localhost during development, but my production server on production)… Not sure.

Describe the solution you’d like

Ideally I could use the code above to fetch data from my API inside getStaticProps. Or alternatively, if context.req was exposed in getStaticProps then I could do something like this to figure out my current hostname:

// This doesn't work.
export const getStaticProps = async (context) => {
    const data = await fetch(context.req.headers.host + '/api/mydata');
}

However the above code doesn’t work because context.req doesn’t exist when using getStaticProps.

Describe alternatives you’ve considered

For now, I’ve had to go with something like this:

export const getStaticProps = async (context) => {
    const URL = process.env.NODE_ENV === 'production' ? 'https://mydeployedsite.com' : 'http://localhost:3000';
    const data = await fetch(URL + '/api/mydata');
}

[0x6a68]

@Timer IMO this documentation leads to the same confusion; https://swr.vercel.app/docs/with-nextjs#pre-rendering

[Timer]

You can refactor your API endpoint into a getData method and just the req/res wrapper!