How to get the StringLength from DataAnnotations

Question

After updating the suggestion I'm still getting the error

Tried both with .SingleOrDefault() or FirstOrDefault()

I need to retrieve the StringLength annotation value and here is my code but I'm getting the following error.

I have tried to implement pretty much the same code from here but getting the error:

Sequence contains no elements

    public static class DataAnnotation
    {
        public static int GetMaxLengthFromStringLengthAttribute(Type modelClass, string propertyName)
        {
            int maxLength = 0;
            var attribute = modelClass.GetProperties()
                            .Where(p => p.Name == propertyName)
                            .Single()
                            .GetCustomAttributes(typeof(StringLengthAttribute), true)
                            .Single() as StringLengthAttribute;

            if (attribute != null)
                maxLength = attribute.MaximumLength;

            return 0;
        }
    }

//calling:

int length = DataAnnotation.GetMaxLengthFromStringLengthAttribute(typeof(EmployeeViewModel), "Name");


public class EmployeeViewModel
{         
    [StringLength(20, ErrorMessage = "Name cannot be longer than 20 characters.")] 
    public string Name{ get; set; }
}

Answer 1

You can get the answer from When you get theLINQ Error “Sequence contains no elements”, this is usually because you are using the First() or Single() command rather than FirstOrDefault() and SingleOrDefault().

So you need to try using SingleOrDefault() instead of Single() like

var attribute = modelClass.GetProperties()
                            .Where(p => p.Name == propertyName)
                            .SingleOrDefault()
                            .GetCustomAttributes(typeof(StringLengthAttribute), true)
                            .SingleOrDefault() as StringLengthAttribute;

Answer 2

I able to figured out, tested and its working great, in case if anybody else is looking!

  StringLengthAttribute strLenAttr = typeof(EmployeeViewModel).GetProperty(name).GetCustomAttributes(typeof(StringLengthAttribute), false).Cast<StringLengthAttribute>().SingleOrDefault();
  if (strLenAttr != null)
  {
     int maxLen = strLenAttr.MaximumLength;
  }