[Blazor] Double routing not working

[ichensky]

1. Create page(change a little bit from basic blazor web app template) that accept several routes:

@page "/fetchdata"
@page "/fetchdata/{page:int}"

and implement simple pagination(several buttons that implement onclick event, which change number of elements of WeatherForecast[] arr and call then UriHelper.NavigateTo($"/fetchdata/{page}"))

2. Lunch app, go from menu to the page /fetchdata, then to the pages: /fetchdata/1, fetchdata/3, /fetchdata/5, etc routing works ok, page rendered, data changed at page and url in browser.
3. If you try to go from page (with number), for ex. /fetchdata/5 to the page: /fetchdata (click on menu item)->
   url in browser will be changed as expected, but page wouldn't be rendered(changed).
   --
   If you go from page for ex. /fetchdata/5 to the page: /fetchdata/0 url in browser will be changed and page will be rendered as expected.

[mkArtakMSFT]

Thank you for filing this issue. In order for us to investigate this issue, please provide a minimalistic repro project that illustrates the problem.

[javiercn]

This is not supported. You can achieve the same thing by using an optional parameter /fetchdata/{page:int?}

[ichensky]

@javiercn
It is not possible to achive this thing with /fetchdata/{page:int?}, becuase threre will be exception:

"System.InvalidOperationException: Invalid template '/fetchdata/{page:int?}'. The character '?' in parameter segment '{page:int?}' is not allowed."

Also, in the documentation: https://docs.microsoft.com/en-us/aspnet/core/blazor/routing?view=aspnetcore-3.0
It is written that multiple route supported by Blazor.

[javiercn]

Maybe I got the syntax wrong.

Reopening for further investigation.

[SteveSandersonMS]

Thanks for reporting it. This is a duplicate of a known issue: #7419

We did fix it at one point, but had to revert the fix after discovering it caused worse issues. I agree we still do need to find a working fix.