C# Override OnActionExecutingAsync Web API call

Question

I'm trying to implement some logging around my web api calls. Nothing too fancy, but I'm still learning async/await and would like the logging to happen without disrupting performance.

Here's an example of what I'd like to implement, just not totally sure how to do it.

public class Logging : ActionFilterAttribute
{
    public override async Task OnActionExecutingAsync(HttpActionContext actionContext, CancellationToken cancellationToken)
    {
        // DoLoggingHere();   ????
        base.OnActionExecutingAsync(actionContext, cancellationToken);
        // OrDoLoggingHere();  ????

        // Also, what does the return look like if any?
    }

    public override Task OnActionExecutedAsync(HttpActionExecutedContext actionExecutedContext, CancellationToken cancellationToken)
    {
        // This method should/could complete before the logging completes.
        base.OnActionExecutedAsync(actionExecutedContext, cancellationToken);

        // Might log here too.
    }
}

Basically I don't want any of my logging to get in the way of the HTTP call. It should be transparent.

Looking for any help!

Possible duplicate of [How and When to use \`async\` and \`await\`](https://stackoverflow.com/questions/14455293/how-and-when-to-use-async-and-await) — Liam, Mar 19 '18 at 16:14

score 2 · Answer 1 · answered Mar 02 '16 at 15:53

2

You can await the call, so that thread is returned to pool for more incoming requests and then do logging after the call completes:

var result = await base.OnActionExecutingAsync(actionContext, cancellationToken);
// logging code here

return result;

answered Mar 02 '16 at 15:53

Ehsan Sajjad

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Could base.OnActionExecutedAsync() be called before my logging finishes? – Richard.Davenport Mar 02 '16 at 16:04
your logging will be done after OnActionExecuting returns some result back, as we are awaiting it, and yes it will complete before OnActionExecuted gets called – Ehsan Sajjad Mar 02 '16 at 16:05
I'm asking for the opposite. I would like to see OnActionExecuted be called first, then my logging. – Richard.Davenport Mar 02 '16 at 16:17
then you have to await ``base.OnActionExecuted`` and after that logging code to be executed – Ehsan Sajjad Mar 02 '16 at 16:25
await base.OnActionExecutingAsync(actionContext, cancellationToken); returns a void, cannot get the result like this var result = ... – gandalf Sep 25 '18 at 14:11

C# Override OnActionExecutingAsync Web API call

1 Answers1