get user's role linq query

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C#

ASP.NET

LINQ

I am trying to build a linq query, which can match up username to its role. I have tested the following code and its giving me no response (no role found) using test api controller.

public  string[] GetRolesForUser(string userName)
{

   // User user = db.api_login.FirstOrDefault(u => u.username.Equals(userName, StringComparison.CurrentCultureIgnoreCase)); //|| u.Email.Equals(username, StringComparison.CurrentCultureIgnoreCase));

    var roles = from r in db.api_login
                where r.role == r.ID &&
                r.username == userName
                    select r.role;
        if (roles != null)
            return roles.ToArray();
        else
            return new string[] { }; ;
}

api_login model class

public partial class api_login
    {
        public string ID { get; set; }
        public string username { get; set; }
        public string password { get; set; }
        public string description { get; set; }
        public string role { get; set; }
    }

Am I missing something? Please help. Many thanks.