I was reading a book about Linq, and saw that the Distinct method has an overload that takes a comparer. This would be a good solution to a problem I have where I want to get the distinct entities from a collection, but want the comparison to be on the entity ID, even if the other properties are different.
According to the book, if I have a Gribulator entity, I should be able to create a comparer like this...
private class GribulatorComparer : IComparer<Gribulator> {
public int Compare(Gribulator g1, Gribulator g2) {
return g1.ID.CompareTo(g2.ID);
}
}
...and then use it like this...
List<Gribulator> distinctGribulators
= myGribulators.Distinct(new GribulatorComparer()).ToList();
However, this gives the following compiler errors...
'System.Collections.Generic.List' does not contain a definition for 'Distinct' and the best extension method overload 'System.Linq.Enumerable.Distinct(System.Collections.Generic.IEnumerable, System.Collections.Generic.IEqualityComparer)' has some invalid arguments
Argument 2: cannot convert from 'LinqPlayground.Program.GribulatorComparer' to 'System.Collections.Generic.IEqualityComparer'
I've searched around a bit, and have seen plenty of examples that use code like this, but no complaints about compiler errors.
What am I doing wrong? Also, is this the best way of doing this? I want a one-off solution here, so don't want to start changing the code for the entity itself. I want the entity to remain as normal, but just in this one place, compare by ID only.
Thanks for any help.