Return list of specific property of object using linq

Question

Given a class like this:

public class Stock
{
    public Stock() {}
    public Guid StockID { get; set; }
    public string Description { get; set; }
}

Lets say I now have a List<Stock>. If I would like to retrieve a list of all the StockIDs and populate it into a IEnumerable or IList. Obviously I can do this.

List<Stock> stockItems = new List<Stock>();
List<Guid> ids = new List<Guid>();

foreach (Stock itm in stockItems) 
{
    ids.Add(itm.StockID);
}

But is there some way I could use Linq to achieve the same result? I thought Distinct() might do it but couldn't work out how to achieve the desired result.

score 156 · Accepted Answer · answered Jul 20 '12 at 07:02

156

var list = stockItems.Select(item => item.StockID).ToList();

answered Jul 20 '12 at 07:02

Amiram Korach

13,056
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3

Lol, well now I feel like an idiot. I should have worked that out. Thank you! – Maxim Gershkovich Jul 20 '12 at 07:05
How can I do the inverse process? – Pedro77 Mar 06 '17 at 13:34
@Pedro77 using `.Reverse()`? – Amiram Korach Mar 06 '17 at 13:35

Ivan Golović · Answer 2 · 2012-08-14T20:37:09.280

3

You could also do it like this:

ids = stockItems.ConvertAll<Guid>(o => o.StockID);

edited Aug 14 '12 at 20:37

answered Jul 20 '12 at 07:24

Ivan Golović

8,732
3
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score 1 · Answer 3 · edited Jun 02 '17 at 09:09

1

How about something like this? Can this be simplified?

List<TranCode> alltrans = new List<TranCode>();

foreach (var bh in obj1.obj2WithCollection.obj2Collection)
{
    alltrans.AddRange(bh.obj3WithCollection.Select(e => e.TransactionCode).ToList());
}

edited Jun 02 '17 at 09:09

BartekR

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answered Jun 01 '17 at 22:28

user2259416

21
2

1

Try use the `SelectMany()` function like this `obj1.obj2WithCollection.obj2Collection.SelectMany(bh => bh.obj3WithCollection.Select(e => e.TransactionCode));` See https://stackoverflow.com/questions/1191054/how-to-merge-a-list-of-lists-with-same-type-of-items-to-a-single-list-of-items?utm_medium=organic&utm_source=google_rich_qa&utm_campaign=google_rich_qa – Dennis Rosenbaum Mar 30 '18 at 11:48

Return list of specific property of object using linq

3 Answers3

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