How to get a distinct list from a List of objects?

Question

I have a List someList.

class MyClass
{
    public int Prop1...
    public int Prop2...
    public int Prop3...
}

Answer 1

I know it's been a while, but I needed the simplest answer and at this time (with .NET 4.5.1) I found the following to be the most straight-forward answer I could get to:

IEnumerable allIds = waitingFiles.Values.Select(wf => wf.groupId).Distinct();

My situation is that I have a ConcurrentDictionary that looks something like: ConcurrentDictionary

The ConcurrentDictionary Values property is basically my List.

*FileModel has a groupId that isn't necessarily unique (though, obviously the key (long) that I use to add the FileModel object into the dictionary is unique to the FileModel).

*Named for clarity in the example.

The point is that I have a large number of FileModels (imagine 100) in the ConcurrentDictionary and within those 100 FileModels there are 5 different groupIds.

At this point I just need a list of the distinct groupId.

So, again if I just had a list of FileModel the code would look like the following:

IEnumerable  allIds = allFileModel.Select(fm => fm.groupId).Distinct();