Description
Is there an existing issue for this?
- I have searched the existing issues
Describe the bug
Catch-all route parameter is effectively optional because it matches against all values, including whitespace and empty strings. For example, consider the following API:
var builder = WebApplication.CreateBuilder(args);
builder.Services.AddControllers();
var app = builder.Build();
app.MapControllers();
app.Run();
[ApiController]
[Route("")]
public class TestController : ControllerBase
{
private readonly IApiDescriptionGroupCollectionProvider _apiDescriptionProvider;
public TestController(IApiDescriptionGroupCollectionProvider apiDescriptionProvider)
{
_apiDescriptionProvider = apiDescriptionProvider;
}
[HttpGet("{**catchAllParameter}")]
public IActionResult Get(string catchAllParameter)
{
var parameter = _apiDescriptionProvider
.ApiDescriptionGroups.Items
.SelectMany(group => group.Items)
.First(api => api.RelativePath.EndsWith("{catchAllParameter}"))
.ParameterDescriptions
.First(parameter => parameter.Name == "catchAllParameter");
Console.WriteLine(parameter.IsRequired); // true
return Ok();
}
}This API can be reached in any of the following ways:
- GET / (with or without trailing slash)
- GET /abc
This behavior of catch-all parameter is consistent with the documentation. It is also consistent between Controllers and Minimal API, except that there is currently a regression bug (#58093) in Minimal API in .NET 8 that prevented it from working (it worked fine in .NET 7).
However, in the above code snippet parameter.IsRequired always reports true. This is effectively a lie because the API can be reached without the parameter being set.
While I understand that ApiExplorer is frequently used for OpenAPI generation purposes, and that the OpenAPI specification does not allow for optional path parameters, I think the ASP.NET Core ApiExplorer's behavior should not be driven solely by OpenAPI. Instead, it should faithfully report the actual API's behavior and let some other component be concerned with OpenAPI compatibility when generating the OpenAPI docs.
Expected Behavior
ApiParameterDescription.IsRequired should report false for catch-all route parameters.
Steps To Reproduce
No response
Exceptions (if any)
No response
.NET Version
8.0.10
Anything else?
No response