Creating Custom Exception Filters

Creating Custom Exception Filters in Asp.Net Core Web API with Examples & Tips

Exception filters are used to catch and process errors in Asp.Net Core Web API applications. They are used to log errors and modify the response sent to the client. Exception filters provide a way to write global error handling logic and can be used to perform additional operations like sending an email or writing to a log file.

Creating Custom Exception Filters

To create a custom exception filter, you can use the IExceptionFilter interface. This interface contains an OnException method which is invoked when an exception is thrown. This method takes an ExceptionContext object which contains the exception, the HttpContext, and the action result.

The following is an example of a custom exception filter:

public class CustomExceptionFilter : IExceptionFilter
{
    public void OnException(ExceptionContext context)
    {
        if (context.Exception is HttpException)
        {
            // Perform some action
        }
    }
}

To register the filter in the Asp.Net Core pipeline, you can add it to the ConfigureServices method:

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc(options =>
    {
        options.Filters.Add(new CustomExceptionFilter());
    });
}

Using Exception Filters

Exception filters can be applied to specific controllers or actions by adding the TypeFilterAttribute attribute:

[TypeFilter(typeof(CustomExceptionFilter))]
public class HomeController : Controller
{
    // ...
}

Tips for Creating Custom Exception Filters

• 
  Always remember to register your custom exception filter in the Asp.Net Core pipeline.
  


• 
  Use the ExceptionContext class to access the exception, the HttpContext, and the action result.
  


• 
  If you want to modify the response sent to the client, you can use the Result property of the ExceptionContext class.
  


• 
  If you want to log the exception, you can use the Logger property of the ExceptionContext class.