string IDataErrorInfo.this[string columnName] { get { string result = null; if (columnName == "ProfileName") { if (ProfileName.IsNullOrTimmedEmpty()) { result = "Please provide a non empty profile name."; } } if (columnName == "Password") { if (Password.IsNullOrTimmedEmpty()) { result = "Please provide a non empty password."; } } if (columnName == "PasswordRepetition") { if (PasswordRepetition.IsNullOrTimmedEmpty()) { result = "Please provide a non empty password repetition."; } if (PasswordRepetition != Password) { result = "Password repetition does not match the password."; } } return(result); } }