Get keys as List<> from Dictionary for certain values

Question

While similar to this question which gave me the LINQ for part of my problem, I'm missing something that seems like it must be obvious to avoid the last step of looping through the dictionary.

I have a Dictionary and I want to get a List of keys for just the items for which the value is true. Right now I'm doing this:

Dictionary<long,bool> ItemChecklist;
...


var selectedValues = ItemChecklist.Where(item => item.Value).ToList();

List<long> values = new List<long>();
foreach (KeyValuePair<long,bool> kvp in selectedValues) {
   values.Add(kvp.Key);
}

Is there any way I can go directly to a List<long> without doing that loop?

Answer 1

To do it in a single statement:

var values = ItemChecklist.Where(item => item.Value).Select(item => item.Key).ToList();

Answer 2

Try using Enumerable.Select:

List<long> result = ItemChecklist.Where(kvp => kvp.Value)
                                 .Select(kvp => kvp.Key)
                                 .ToList();