C# How to use DataAnnotations StringLength and SubString to remove text

Question

I have a model classes that has a description property with a data annotation attribute of StringLength and length is set to 100 characters. When this property is more than 100

Answer 1

Create a view model that doesn't have a data annotation for the length, then you can map it to the entity model and truncate the value if it's longer than 100.

Answer 2

You could always check the attribute value using reflection, though that approach is not the best if you can get around it - it's not pretty:

var attribute = typeof(ModelClass).GetProperties()
                                  .Where(p => p.Name == "Description")
                                  .Single()
                                  .GetCustomAttributes(typeof(StringLengthAttribute), true) 
                                  .Single() as StringLengthAttribute;

Console.WriteLine("Maximum Length: {0}", attribute.MaximumLength);    

Answer 3

Why all the hassle? Why not

private string _description = string.Empty;

[StringLength(100, ErrorMessage = "Description Max Length is 100")]
public string Description 
{  
    get { return _description; }
    set { _description = value.Substring(0,100); };  // or something equivalent
}