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.

"extract all the List from List in one single List" What? What do you want to extract? Can you please re-formulate? — MakePeaceGreatAgain, Dec 11 '15 at 15:35
*i need to extract all the List* isnt `Activities` already all the list? — Ňɏssa Pøngjǣrdenlarp, Dec 11 '15 at 15:36
Is this the same as the following? http://stackoverflow.com/questions/720609/merge-two-object-lists-with-linq — Jarrett Robertson, Dec 11 '15 at 15:36
Possible duplicate of [How to merge a list of lists with same type of items to a single list of items?](http://stackoverflow.com/questions/1191054/how-to-merge-a-list-of-lists-with-same-type-of-items-to-a-single-list-of-items) — Dzyann, Dec 11 '15 at 15:39

Hamid Pourjam · Accepted Answer · 2015-12-11T15:40:27.520

4

You can use SelectMany

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

edited Dec 11 '15 at 15:40

answered Dec 11 '15 at 15:36

Hamid Pourjam

For completeness of the answer You might consider adding comprehension syntax version. – Grzegorz Sławecki Dec 11 '15 at 15:45
What is comprehension syntax? You mean query syntax? – Robert McKee Dec 11 '15 at 16:48

score 1 · Answer 2 · answered Dec 11 '15 at 15:36

1

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

answered Dec 11 '15 at 15:36

Perfect28

2 Answers2