c# - Intercept all WebApi calls before the route matching occurs

Question

I am looking for a way to intercept/grab the request being made before matching to a route. For example, I have multiple controllers and routes set up, but I want some mechanism in which will be hit before the route method is hit. It would be highly preferable if this mechanism were able to get the route params that were sent.

I have been unable to find something similar to what I am looking for (but perhaps not being well versed in Web API I am searching with the wrong keywords).

Answer 1

What you need is action filters. You can apply action filters directly to controllers as attributes, the caveat with Action filters is that at this point the controller route is already known but you can still control (very much like AOP) if the action method can be executed or not:

ASP.NET Web API ActionFilter example

Look at how you can use an action filter, in this case for logging:

public class LogActionFilter : ActionFilterAttribute 
{
    public override void OnActionExecuted(HttpActionExecutedContext actionExecutedContext)
    {
        Log(actionExecutedContext.ActionContext.RequestContext.RouteData);

        base.OnActionExecuted(actionExecutedContext);
    }

    private void Log(System.Web.Http.Routing.IHttpRouteData httpRouteData)
    {
        var controllerName = "controller name";
        var actionName = "action name";
        var message = String.Format("controller:{0}, action:{1}", controllerName, actionName);

    Debug.WriteLine(message, "Action Filter Log");
    }
}

How to log which action method is executed in a controller in webapi

You can also use message handlers, which are executed before the controller is resolved:

HTTP Message Handlers in ASP.NET Web API