dynamic routes param value is not defined for server side render when literal dynamic route value is provided as the pathname

Bug report

Describe the bug

When using dynamic routes the param value is not defined when navigating to a page whose pathname is the string literal value for the dynamic route.

From the dynamic routes example:

Given a page defined as pages/post/[pid].js, navigating to /post/[pid] will not set the pid param value for the server side render if getInitialProps is defined for the page.

If getInitialProps is not provided, then the router correctly extracts the pid param. When getInitialProps is provided, the router does not extract the pid param, and the context argument for getInitialProps will not include pid in the query attribute.

Note: This only occurs for the server side render. When navigating client side, everything works as expected.

To Reproduce

Steps to reproduce the behavior, please provide code snippets or a repository:

1. Go to https://3q2nu.sse.codesandbox.io/
2. Click on the [day] link
3. Observe the values for router and gIP (both are [day] as expected)
4. Reload the page (https://3q2nu.sse.codesandbox.io/days/[day])
5. Observe the values for router and gIP (both are undefined)

codesandbox: https://codesandbox.io/s/romantic-raman-3q2nu

Note: Removing DayPage.getInitialProps from the sandbox above will cause the router value to be correct both when navigating on the client and on the sever side render.

Expected behavior

The query param value should always be set.

Given a page defined as pages/post/[pid].js, navigating to /post/[pid] should set the pid param value to [pid] in both server and client side contexts.

Screenshots

If applicable, add screenshots to help explain your problem.

System information

• OS: [macOs]
• Browser [N/A]
• Version of Next.js: [9.5.3, present on latest]
• Version of Node.js: [12.x]

[rmsheppard]

I’m having same issue. When using dynamic routes /pages/account/info/[tab]

When I reload the page as such localhost:3000/account/info/user. The correct page is displayed however the querystring tab is not passed to the page. That is at least how I expected it to work. If I do use the useRouter hook it does provide a router object with the correct querystring params. I could be wrong but it seems like a bug. Also this documentation doesn’t seem correct:

Unless you mean the query object on the router.

[JonatanLindstrom]

Do we have any updates on this? I’m seeing the same issue in v11.1.0. Would be good with a native solution rather than having to write a function to run in each getServerSideProps that depends on the params existence.