Log User Activity on ASP.NET MVC Application

I just stumbled on these 2 posts by Rion Williams that describe a very straightforward way of doing this:

Implementing Audit Trails using ASP.NET MVC ActionFilters

Creating Advanced Audit Trails using ActionFilters in ASP.NET MVC

The advanced post is really great as you can store the request's data and further filter that data.

I'll implement this right now in my app.

@Rory's idea is excelent. PostSharp is just what you need for this, you might consider coupling it with ASP.net Health Monitoring

You could try using a PostSharp aspect to perform the logging for you, it's multi-cast functionality might come in handy for something like that. If it's not an option, then a Module would probably be the easiest to implement (assuming you can get the required user information at that point in the pipeline).

Warning: This was written in 2009 for MVC .NET RC1 and may not be syntactically correct anymore.

Action Filter Attributes are perfect for this, just put a call to [YourAttributeName] at the top of your controller (or if you have an Application Controller which your other controllers inherit from, you only need it once in your application).

For example:

namespace the_name_space
{
    [Log]
    public class ApplicationController : Controller
    {

From this point onwards this attribute will be called before each action is run in your controller(s), you can also specify this on just an action by calling [Log] just before it in the same fashion.

To get the logging functionality which you require, you will most likely want to override OnResultExecuting and OnResultExecuted, both of which are pretty self explanatory.

For example:

public class LogAttribute : ActionFilterAttribute
{
    protected DateTime start_time;

    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        start_time = DateTime.Now;
    }

    public override void OnResultExecuted(ResultExecutedContext filterContext)
    {
        RouteData route_data = filterContext.RouteData;
        TimeSpan duration = (DateTime.Now - start_time);
        string controller = (string)route_data.Values["controller"];
        string action = (string)route_data.Values["action"];
        DateTime created_at = DateTime.Now;
        //Save all your required values, including user id and whatnot here.
        //The duration variable will allow you to see expensive page loads on the controller, this can be useful when clients complain about something being slow.
    }
}