Can I use .ToString().IsNullOrEmpty() on a StringBuilder object

Question

 /*Class definition*/
public class ConcreteClassModel : BaseModel
{
...
public bool IntersectsWith(ConcreteClassModel ccm)
    {
        ccm.StartDateDT = DateTime.Parse(ccm.StartDate);
        ccm.EndDateDT = DateTime.Parse(ccm.EndDate);
        this.StartDateDT = DateTime.Parse(this.StartDate);
        this.EndDateDT = DateTime.Parse(this.EndDate);

        return !(this.StartDateDT > ccm.EndDateDT || this.EndDateDT < ccm.StartDateDT);
    }
}
/*Inside Controller Method*/
List<ConcreteClassModel> periods = LoadAllByParameters<ConcreteClassModel>(
            ccm.CoverId, x => x.CoverId,
            ccm.SectionId, x => x.SectionId);
var intersectingPeriods =
            periods.Where(x => x.IntersectsWith(ccm));
StringBuilder partReply = intersectingPeriods.Aggregate(new StringBuilder(), (a, b) => a.Append(b));

********if (!partReply.ToString().IsNullOrEmpty())***************************
        {
            string reply =
                "<div id='duplicateErrorDialog' title='Duplication Error'><span> Duplicate Period(s)</br>" +
                partReply + "</span></ div >";

            return Json(reply, JsonRequestBehavior.AllowGet);
        }    
return Json(null, JsonRequestBehavior.AllowGet);

The above seems to work fine and if no duplicate date periods are found the null responce will trigger my javascript to save. However is it ok to use: if (!partReply.ToString().IsNullOrEmpty()) As StringBuilder does not have its own .IsNullOrEmpty() equivalent? Every comment, question etc that I can find relates to Strings only, and cant see anything on MSDN!

Answer 1

In your case, partReply can never be null or empty, because Enumerable.Aggregate throws an InvalidOperationException when there are no input elements. Your code is crashing.

In general cases, you can compare the Length property with 0, e.g.:

if (partReply.Length > 0)