我有这个控制器和动作：
[Route("categories")]
public class CategoriesController : Controller
{
[HttpGet("{*category:regex(^[[A-Za-z0-9/]]*$)}")]
public IActionResult ViewObjectsInCategory([FromRoute] string category)
{
return Ok(category ?? ""); // for now, just echo what you inputted
}
}
我打算执行此操作以接受以下网址路由：
/categories /categories/abc /categories/abc/def /categories/abc/def/1234/ghi
从本质上讲，只要是大写字母，小写字母，数字或正斜杠，用户都可以在URL中将/categories放在任意位置（不包括任何内容）。如果用户输入的字符无效，他们应该收到404。
发布的代码将正确路由我列出的所有请求，除了第一个条目（/categories）。当我希望它执行我的动作时，它将返回404。
看看日志，ASP.Net核心绝对拒绝执行我的操作的路线：
info: Microsoft.AspNetCore.Hosting.Internal.WebHost[1]
Request starting HTTP/1.1 GET http://localhost:5000/categories
dbug: Microsoft.AspNetCore.HostFiltering.HostFilteringMiddleware[0]
Wildcard detected, all requests with hosts will be allowed.
dbug: Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware[4]
The request path /categories does not match a supported file type
dbug: Microsoft.AspNetCore.Routing.Matching.DfaMatcher[1001]
1 candidate(s) found for the request path '/categories'
dbug: Microsoft.AspNetCore.Routing.Matching.DfaMatcher[1003]
Endpoint 'MyApp.Controllers.CategoriesController.ViewObjectsInCategory (MyApp)' with route pattern 'categories/{*category:regex(^[A-Za-z0-9/]*$)}' was rejected by constraint 'category':'Microsoft.AspNetCore.Routing.Constraints.RegexInlineRouteConstraint' with value '(null)' for the request path '/categories'
dbug: Microsoft.AspNetCore.Routing.Matching.DfaMatcher[1004]
Endpoint 'MyApp.Controllers.CategoriesController.ViewObjectsInCategory (MyApp)' with route pattern 'categories/{*category:regex(^[A-Za-z0-9/]*$)}' is not valid for the request path '/categories'
dbug: Microsoft.AspNetCore.Routing.EndpointRoutingMiddleware[2]
Request did not match any endpoints
如何使此路由属性既接受“空”值（/categories），又要验证是否存在（如果存在）任何用户输入的值都没有无效字符？