When paired with a custom server setPreviewData is not working

[cidicles]

Bug report

Describe the bug

When using a custom server the setPreviewData function is not setting the cookies as expected. If next start or next dev is used the cookies will be set.

To Reproduce

1. Create a next site using a custom server.
2. Follow the instructions for preview mode
3. Visit the /api/preview route

Expected behavior

The __next_preview_data and __prerender_bypass cookies are set.

System information

• OS: macOS
• Version of Next.js: 9.5.3
• Version of Node.js: 10.15.0

[SamStenton]

Hey so I had this same issue when using express as my custom server on localhost. When I inspected the request that sets setPreviewData it was complaining that the cookie not being set over HTTPS.

Workaround:

...

res.setPreviewData({})

// Remove secure requirement for Cookies if on localhost
if(process.env.NODE_ENV === 'development') {
	const cookies = res.getHeader('Set-Cookie');
  	res.setHeader('Set-Cookie', cookies.map((cookie) => cookie.replace('Secure;', '')))
}

...

I'm going to dig into a cleaner way of handling this.

Edit

Looks like this is an issue with https://github.com/vercel/next.js/blob/canary/packages/next/next-server/server/api-utils.ts#L473

Logging out the value of process.env.NODE_ENV outputs undefined

[ambrauer]

Just ran into this one as well. In my case for the workaround, I also had to set the SameSite cookie to Lax.

  if(process.env.NODE_ENV === 'development') {
    const cookies = res.getHeader('Set-Cookie') as string[];
    res.setHeader('Set-Cookie', cookies.map((cookie) => cookie.replace('Secure;', '').replace('SameSite=None', 'SameSite=Lax')))
  }