Retrieve a list B from a list A

Question

I have two classes.

class Lead
{
    public List<Activity> Activities { get; set; }
}

class Activity
{
    public long ActivityId { get; set; }
}

Now I need to extract all the List<Activity> from List<Lead> in one single List<Activity>.

List<Lead> leads;
List<Activity> Activities = leads.[--Some Linq Code--];

Any help & suggestion are welcome.

Answer 1

You can use SelectMany

var allActivities = leads.SelectMany(x=>x.Activities);

Answer 2

Use SelectMany and ToList :

List<Activity> Activities = leads.SelectMany(s => s.Activities).ToList();