Should I cast the value returned from User.Identity.GetUserId() to make it a GUID?

Question

I created the following class:

public class Config
{
    public Guid UserId { get; set; }
    public string AdminJSON { get; set; }
    public string UserJSON { get; set; }
}

When I query the data I am using:

Config config = await db.Configs.FindAsync(User.Identity.GetUserId());

Is this the correct way to do the find. It seems that User.Identity.GetUserId() returns a string. Should I be casting this to return a GUID.

I also have another problem with this:

UserId = User.Identity.GetUserId()   

This also fails. I tried to do a cast by adding (Guid) before the User.Identity.GetUserId() however this gives a message saying Error 1 Cannot convert type 'string' to 'System.Guid'

It errors out as it cannot

Answer 1

You need to use Guid.Parse(User.Identity.GetUserId()) or better fail proof method

Guid userId;
bool worked=Guid.TryParse(User.Identity.GetUserId(),out userId);
if(worked) 
{
    //go ahead
}
else 
{
    throw new Exception("Invalid userid"); 
}

Answer 2

It seems like a bad idea to convert to a type that is stricter than that handed to you by a third party library. For this reason alone I would keep UserId as a string. If you find it becomes a performance problem you can always optimize it later.

If you're just starting out with asp.net Identity I would strongly suggest using a default project as it is already wired up.

Here are some articles that helped me when I first got started:

• http://www.codeproject.com/Articles/674760/Code-First-Migration-and-Extending-Identity-Accoun
• http://www.asp.net/mvc/tutorials/mvc-5/create-an-aspnet-mvc-5-app-with-facebook-and-google-oauth2-and-openid-sign-on