Question

I have a class with this structure:

public class BusinessObject
{
    public int Column1 { get; set; }
    public int Column2 { get; set; }
    public string Column3 { get; set; }
    public int Column4 { get; set; }   
}

and I have a collection of objects of this type call BusinessObjectCollection. If I want an array of values that are distinct for only Column2… what must I do?

What if I dont know the property that I need… so if i have ColumnTitle as a String… and whatever the value of ColumnTitle… I want the distinct values for that property

Answer 1

Assuming you want the result to be an IEnumerable<BusinessObject>, so that Column2 is only used for implementing distinctness, there are two options:

• Implement IEqualityComparer<BusinessObject> in a way which uses Column2, and pass that into Distinct

• Use DistinctBy from MoreLINQ:

  var distinct = original.DistinctBy(x => x.Column2);
  

Obviously the second is simpler, but it does require an extra library (or copying just the code for DistinctBy).