C# LINQ - Group by

Question

I would like to Sum grouped items. I would like to do keep simple LINQ syntax.

What I need to fix in the code to get items for key. I am trying like "g[g.Key].Count()", which doesn't work.

public class Order
{
    public string Id { get; set; }
    public string Name { get; set; }
    public string Group { get; set; }
}

public class Group
{
    public string GroupId { get; set; }
    public string Count { get; set; }
}     


**var groupedOrd = orders.GroupBy(f => f.Group);**
List<Group> groups = new List<Group>();
foreach(var g in groupedOrd)
{
   groups.Add(new Group() { GroupId = g.Key, Count = g[g.Key].Count() });
}

Does this answer your question? [Group by in LINQ](https://stackoverflow.com/questions/7325278/group-by-in-linq) — nilsK, Jun 10 '20 at 13:29

Guru Stron · Accepted Answer · 2020-06-10T14:05:29.737

6

GroupBy returns IEnumerable of IGrouping<TKey,TElement> which implements IEnumerable<T> so you can just do g.Count():

var groups  = groupedOrd
    .Select(g => new Group { GroupId = g.Key, Count = g.Count() } )
    .ToList();

Also your Group.Count property is a string for some reason, so you will need to change it to int or do g.Count().ToString()

edited Jun 10 '20 at 14:05

answered Jun 10 '20 at 13:22

Guru Stron

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2

Technically the result of `GroupBy` is a `IEnumerable>` and `IGrouping` is `IEnuemrable` which is why you can do the `g.Count()`. – juharr Jun 10 '20 at 13:26
@juharr, yes, was adding links and signatures, thank you. – Guru Stron Jun 10 '20 at 13:27

C# LINQ - Group by

1 Answers1