Logging Umbraco Api errors with a custom action filter

How to log exceptions in Umbraco Api Controller?

In this short article, I am going to present a simple technique for logging exceptions in UmbracoApi with ActionFilters.

There are many ways to handle exceptions in Umbraco CMShowever, logging using filters has quite a benefits:

  • Short implementation time
  • Can be applied globally or only on individual endpoints
  • Works asynchronously

Filter implementation

First, you should create UmbracoCustomLoggingAttribute class extending ActionFilterAttribute and override OnActionExecutedAsync method.

Now, we can access the HttpActionExecutedContext object and the inspect “Exception” property.

When the exception property is not empty – just log the exception with a built-in logger for further diagnosis.

public sealed class UmbracoCustomLoggingAttribute : ActionFilterAttribute
   public override Task OnActionExecutedAsync(HttpActionExecutedContext actionExecutedContext, CancellationToken cancellationToken)
      if (actionExecutedContext.Exception != null)
         Current.Logger.Error<UmbracoCustomLoggingAttribute>(actionExecutedContext.Exception, "An unexpected error has occurred");

      return base.OnActionExecutedAsync(actionExecutedContext, cancellationToken);

Using the filter

Once the attribute is ready, it’s possible to decorate any UmbracoApiController with a new filter as follows:

public class TestUmbracoApiController : UmbracoApiController
   public IHttpActionResult EndpointA(string id)
      return Json("Hello from Endpoint A");

   public IHttpActionResult EndpointB(string id)
      return Json("Hello from Endpoint B");

Thanks to this, each error will be logged for further investigation. Naturally, you can put attributes on specific methods as you like and log errors only for chosen endpoints. When using filters, we have a choice and flexibility.

Configure the logging middleware with the right level

 Tip! if you run the site in a production environment, it is worth setting the appropriate login level. Keep logging levels as high as possible to get better overall performance.

Umbraco 8 allows you to easily save logs using the popular Serilog library.

To set the logging level to “Error” and above with Serilog you need to:

  • Go to \config directory
  • Find serilog.config file and open the configuration file
  • Go to <appSettings> section
  • Set “serilog:minimum-level” value as “Error” (serilog supports many log levels such as Verbose, Debug, Information, Warning, Error, Fatal)
<?xml version="1.0" encoding="utf-8" ?>
        <!-- VALID Values: Verbose, Debug, Information, Warning, Error, Fatal -->
        <add key="serilog:minimum-level" value="Error" />

Final words

In the end, good luck to you, and Happy Umbraco logging!­čśë

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