Simple LinQ question: convert [][] to []

Question

I would like to get collection or list of Item objects, but I get array of arrays now.

Item[][] s = employees.Select(e => e.Orders.Select(o => new Item(e.ID, o.ID)).ToArray()).ToArray();

Can anyone select me solution to do it?

P.S. just LinQ solution :)

score 5 · Accepted Answer · answered Apr 15 '10 at 11:10

5

You need to use SelectMany to concatenate result sets.

var items = employees.SelectMany(e => e.Orders.Select(o => new Item(e.ID, o.ID)));

answered Apr 15 '10 at 11:10

Nick Larsen

score 5 · Answer 2 · answered Apr 15 '10 at 11:19

5

For what it's worth, this can be written somewhat more succinctly and clearly in LINQ syntax:

var s = from e in employees
        from o in e.Orders
        select new Item(e.ID, o.ID);

answered Apr 15 '10 at 11:19

Will Vousden

1

While I agree with this, instead of changing the syntax used, I would have argued that `Orders` should have a reference back to `Employee` and there is no need for `Item`. – Nick Larsen Apr 15 '10 at 11:43
+1. Note that this syntax is actually translated into SelectMany. Use whatever you find more readable. The generated code is exactly the same. – Niki Apr 15 '10 at 14:57

score 3 · Answer 3 · answered Apr 15 '10 at 11:10

3

answered Apr 15 '10 at 11:10

Niki

score 3 · Answer 4 · edited May 23 '17 at 11:55

3

Have a look at Enumerables.SelectMany(), see the example in this Stack Overflow question.

edited May 23 '17 at 11:55

Community

answered Apr 15 '10 at 11:11

Paul Ruane

4 Answers4