Data transfer object with O(1) lookup

Hi I want to use a datatransfer object that is got by reading a database using NHibenrate and that has like 1000 records and I need to use this DTo carefully wherein based on a certain key i select a value. My DTO will be seomthing like this.

public class DTO
{
    string name;
    int id;
    int schoolId;
    double value;
} 

Now the problem is I get this as an enumerable.. Now from this enumerable based on the schoolid id and name i need to select a value which I do as of now as follows:

 DtoList.Where(x=>x.name="name" && x.id=1 && x.schoolId=2).First();

Now the problem with this is it is an O(n) lookup and I want it to be O(1) which can be done by using an IDictionary.

I am wondering if I can make this DTO implement IDitcionary and then do the same. \

Is that possible? I think this is more from a c# perspective.

Also from an NHibernate perspective how this will work o开发者_开发技巧ut.

If you construct the list once and then look it up multiple times, maybe it's worth creating another object, which will consist of a dictionary, and create it from a collection of DTOs:

struct Key
{
    string Name;
    int Id;
    int SchoolId;
}

class DictionaryObject
{
   IDictionary<Key, double> _dict;

   public DictionaryObject(IEnumerable<Dto> dtoList)
   {
      _dict = dtoList.ToDictionary(
             o => new Key { Name = o.Name, Id = o.Id, SchoolId = o.SchoolId },
             o => o.Value);
   }

   double GetValue(string Name, int Id, int SchoolId)
   {
      // if the key exists then...
      return _dict[new Key { Name = Name, Id = Id, SchoolId = SchoolId }];
   }

   ...
}