How to convert List<long?> to ISet<long>

Question

There is a methods which is accepting a parameter of type List<long?>, I need to assign it to someTestModel ids, which are of type ISet<long>.

public void testM1(List<long?> testIds)
{
    var request = new someTestModel { ids= testIds };
}

Answer 1

There's two things we'd need here:

• a concrete type to implement ISet<T> - presumably HashSet<T> will suffice
• to change from long? to long - presumably by just ignoring any that are null

So, something like:

var hash = new HashSet<long>();
foreach(var id in testIds) {
    if(id.HasValue) hash.Add(id.Value);
}
var request = new someTestModel{ ids = hash};

?