Using Linq to return a Comma separated string

Question

I have a class in my application

public class ProductInfo
{
  public int ProductId {get;set;}
  public int ProductType{get;set;}
}

I want to write a linq query which can return me a list of ProductIds in a comma separated format where ProductType is equal to certain number ?

I tried using string.join with my Linq statement but it didn't seem to work.

Answer 1

var s = string.Join(",", products.Where(p => p.ProductType == someType)
                                 .Select(p => p.ProductId.ToString()));