How to retrieve the original endpoint from within a exception handler?

[nicystalker]

Is there a way to retrieve the endpoint from which the error/exception originates?

I tried using, for exemple, this snippet:

app.UseExceptionHandler(exceptionHandlerApp => exceptionHandlerApp.Run(context =>
{
    var endpoint = context.GetEndpoint();
    return Results.Problem().ExecuteAsync(context);
}));

But endpoint is null, and also in this way:

app.UseExceptionHandler("/error");
app.Map("/error", (HttpContext context) =>
{
    var endpoint = context.GetEndpoint();
});

But endpoint here is "/error" itself.

Debugging the code, I found out that HttpContext.Items contains one element in its dictionary. This entry has a key "__OriginalEndpoint" whose corresponding value is, well, the original endpoint, which is exactly what I would like to retrieve:

It was introduced here: #52652 (comment)

It seems like a internal thing, so I'll avoid using it.

---

I have all my endpoints following this pattern:

        RouteGroupBuilder group = app
            .MapGroup("/v1")
            .WithOpenApi()
            .AllowAnonymous()
            .WithTags("Transactions");

        group
            .MapPost("/transactions", Create);

        // other endpoints in the group

---

I've referred to:

• https://learn.microsoft.com/en-us/aspnet/core/fundamentals/minimal-apis/handle-errors?view=aspnetcore-8.0;
• https://learn.microsoft.com/en-us/aspnet/core/fundamentals/routing?view=aspnetcore-8.0#endpoint-metadata;
• https://learn.microsoft.com/en-us/aspnet/core/fundamentals/minimal-apis/min-api-filters?view=aspnetcore-8.0;

---

To add context, I need this to migrate our exception handler from Fast Endpoints to Minimal API, more details here: FastEndpoints/FastEndpoints#875; I considered using EndpointFilter, but using exception handler seemed more natural, and I don't have to add an EndpointFilter to each group--just catch all errors.

[nicystalker]

To achieve something similar to the internal __OriginalEndpoint I created a middleware that checks for a specific part of the route pattern, since it has a predictable prefix:

app.Use((context, next) =>
{
    if (context.GetEndpoint() is RouteEndpoint endpoint &&
        endpoint.RoutePattern.PathSegments[0].Parts[0] is RoutePatternLiteralPart { Content: "api" })
    {
        context.Items.Add("OriginalEndpoint", endpoint);
    }

    return next(context);
});