Missing trailing backslash after pathBase when Path is empty

[rbans96]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Found a bug that backslash is missing after PathBase, if Path is empty.

Expected Behavior

If pathBase is non empty and Path is empty, then add a trailing backslash after pathBase in the route url.

Actual url: /twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com?_type=Patient&_count=500&ct=er97f5lRTbShgbGOqaGBuaGFqbGJiZmhibmRobGZUSwAAAD%2F%2Fw%3D%3D

Expected url: /twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com/?_type=Patient&_count=500&ct=er97f5lRTbShgbGOqaGBuaGFqbGJiZmhibmRobGZUSwAAAD%2F%2Fw%3D%3D

The issue is here

aspnetcore/src/Http/Http.Extensions/src/UriHelper.cs

Line 36 in 481e472

string combinePath = (pathBase.HasValue || path.HasValue) ? (pathBase + path).ToString() : "/";

Steps To Reproduce

• Search URl: https://localhost:44349/twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com/?_type=Patient&_count=500
  _Host: localhost:44349, basePath: /twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com, Path: Empty, Query parameter: type=Patient&count=500
• In our implementation, we are calling AspnetCore UrlHelper.RouteUrl() to get the route url
• Further debugging, LinkGeneratorExtensions.GetPathByRouteValues -> GetPathByAddress() -> DefaultLinkGenerator.GetPathByEndpoints() -> TryProcessTemplate() fetches pathBase as ""/twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com" and Path as ""(empty)
• UriHelper.BuildRelative constructs the url as below
  /twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com?_type=Patient&_count=500&ct=er97f5lRTbShgbGOqaGBuaGFqbGJiZmhibmRobGZUSwAAAD%2F%2Fw%3D%3D

Expected url: /twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com/?_type=Patient&_count=500&ct=er97f5lRTbShgbGOqaGBuaGFqbGJiZmhibmRobGZUSwAAAD%2F%2Fw%3D%3D

Exceptions (if any)

No response

.NET Version

No response

Anything else?

No response

[Tratcher]

Search URl: https://localhost:44349/twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com/?_type=Patient&_count=500
_Host: localhost:44349, basePath: /twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com, Path: Empty, Query parameter: type=Patient&count=500

This seems wrong, Path should be "/" at this stage. This likely causes the later issues. Where are you reporting this from?

The UriHelper code is correct, it should not add a trailing slash when Path is empty. The real issue is that Path should not be empty.

[rbans96]

Thanks for the reply. Potentially then problem could be somewhere before it hit the UriHelper that fetched the Path as empty instead of '/'- DefaultLinkGenerator.GetPathByEndpoints() -> TryProcessTemplate() fetches pathBase as ""/twci369916wu2hsws-twci369916wu2hsws.fhir.mshapis.com" and Path as ""(empty)

[amcasey]

@Tratcher Why is the UriHelper code converting everything to strings? It looks like PathString specifically supports addition of PathString and QueryString and those helpers seem to massage the slashes.

i.e. Why isn't it?

string combinePath = (pathBase.HasValue || path.HasValue) ? (pathBase + path) : new PathString("/");
return combinePath + query + fragment;

[Tratcher]

That should be equivalent. However it's unrelated to this issue, the problem happens before UriHelper is even called. Why is Path empty instead of "/"?