Month: October 2022

To handle exceptions on Controller/Action level Exception Filters are used.

[TypeFilter(typeof(SampleExceptionFilter))]
public class ExceptionController : Controller

Exception Filters are implemented using IExceptionFilter with OnExcetion method override to handle exceptions.

Exception Filters can be applied to Controller and Action level.

Further read:

https://learn.microsoft.com/en-us/aspnet/core/mvc/controllers/filters?view=aspnetcore-7.0#exception-filters

https://learn.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.mvc.filters.iexceptionfilter?view=aspnetcore-7.0

To add global exception handling in ASP.NET Core just use configuration method:

app.UseExceptionHandler

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/error-handling?view=aspnetcore-6.0#exception-handler-lambda

Pretty much everything. Default ASP.NET Core request handling pipeline is consisting of bunch of middlewares:

• Authentication
• Authorization
• CORS
• HTTP Logging
• MVC
• Static Files
• other

Whole list of built-in middlewares can be found here:

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/middleware/?view=aspnetcore-7.0#built-in-middleware

There is possibility to write custom middleware too.

There are 2 ways of writing OWIN middleware in ASP.NET Core.

• Pure OWIN – usefull if you want to integrate with OWIN compatible module but not written in C#
• ASP.NET Core OWIN middleware

ASP.NET Core Middleware:

This type of middleware can be:

• delegate of Func<HttpContext, Func<Task>, Task>
• class with IMiddleware imlementation

app.Use(async (context, next) =>
{
    // Do work that can write to the Response.
    await next.Invoke();
    // Do logging or other work that doesn't write to the Response.
});

Pure OWIN Middleware:

This rather would be used to integrate with OWIN middlewares written in different language, so that ASP.NET Core implementation directly is not possible.

• delegate of type Func<IDictionary<string, object>, Task>
• must set keys of owin.ResposeBody and owin.ResponseHeaders

usage in ASP.NET Core pipeline:

public void Configure(IApplicationBuilder app)
{
    app.UseOwin(pipeline =>
    {
        pipeline(next => DelegateTask);
    });
}

Further read:

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/middleware/?view=aspnetcore-6.0

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/owin?view=aspnetcore-6.0