MVC Validation

 var currentAddress = bingRepository.ToDatabaseAddress(model.CurrentAddress, LocationTypes.Current, out errorString);

//If currentAddress is null and error message value was found, set error in errorstring.then add below lines

                if (!string.IsNullOrEmpty(errorString))
                {
                    string wrongAddressErrorString = errorString;
                    ModelStateDictionary modelState = new ModelStateDictionary();
                    modelState.AddModelError(string.Empty, string.IsNullOrWhiteSpace(wrongAddressErrorString) ? "Not  update error" : wrongAddressErrorString);
                    return false;
                }