How to account for an argument to my method being `null` instead of an `int`

Question

I need to know how to account for an argument to my method being null instead of an int .

I have this method which is supposed to receive an int

    [HttpGet]
    public ActionResult UpdateUser(int userId){ }

However when ever the session times out and I log back in while in the middle of calling this method it receives a null instead of an int.

This causes this error:

The parameters dictionary contains a null entry for parameter 'userId' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult UpdateUser(Int32)' in 'Controllers.UserController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Parameter name: parameters

I need a way to account for receiving a null argument.

So far I have tried overloading the method with a nullable int type like this

    [HttpGet]
    public ActionResult UpdateUser(int? userId){ }

but this just ends up receiving every UpdateUser() call and converting the value to null.

Any suggestions?

Answer 1

The signature for the overload, which won't be supplied the userId is probably:

[HttpGet]
public ActionResult UpdateUser(){ }

i.e. no userId was supplied, rather than it being supplied with a null value.

I say "probably" as it is possible that your request does in fact have the parameter/argument specified with no value.

If this is the case, you should probably use just the one signature:

[HttpGet]
public ActionResult UpdateUser(int? userId){ }

With a check...

if (userId.HasValue)
{
    // ok... you can use userId.Value
}
else
{
    // not ok...
}