How to handle empty variables in a try/catch block?

Question

So I have button that sends a POST request along with two variables, an outbox ID called oid, and an email. The controller takes in the variables and performs a method call, the end goal would be to send a JSON response back depending on whether it fails or succeeds.

I have the following written for the controller:

public ActionResult ResendEmail(int oid, string email = null)
{
    try
    {
        Outbox.ResendEmail(oid, email);
        return Json(new { success = true, message = "Email has been queued to be resent", status = (int)HttpStatusCode.OK });
    }
    catch (Exception)
    {
        return Json(new { success = false, message = "An error occurred when attempting to resend the email", status = (int)HttpStatusCode.InternalServerError });
    }
}

Problem here, is that 1. If the oid and/or email is empty, the method call for Outbox.ResendEmail(oid, email) will still be called and a success json response will be returned. I'm also unsure if this is a proper way to use try/catch.

Feels like I should re-write how i'm handling this. Maybe an if statement to check for an existing oid and email followed by a try/catch?

Answer 1

The try/catch is useful for handling exceptions. If Outbox.ResendEmail() throws an exception, then the try/catch will do its thing.

However, if Outbox.ResendEmail() will not throw an exception when given an incorrect oid or an incorrect, empty, or null email, then you need something else, such as an if-statement.

In addition, it probably is not appropriate to return a 500 error due to invalid parameters. It's not really a server error if the user passes a null email address.

I would recommend something like the following:

public ActionResult ResendEmail(int oid, string email = null)
{
    // If you have a way to validate the oid, then use that instead of just checking for 0:
    if (oid == 0)
    {
        return // one of the 400 level responses
    }

    // Do you have a way to validate the email address?
    // If so, probably do that here, depending on how Outbox.ResendEmail() behaves
    if (string.IsNullOrWhiteSpace(email))
    {
        return // one of the 400 level responses
    }

    try
    {
        Outbox.ResendEmail(oid, email);
        return Json(new { success = true, message = "Email has been queued to be resent", status = (int)HttpStatusCode.OK });
    }
    catch (Exception)
    {
        return Json(new { success = false, message = "An error occurred when attempting to resend the email", status = (int)HttpStatusCode.InternalServerError });
    }
}