How to use GroupBy using Dynamic LINQ
Solution 1
There is default it
defined, you can use it to return matched elements:
var mydataGrouped = mydata.GroupBy("Shop", "it");
To iterate through results you should additionally Select
elements to name it and use dynamic
s:
var mydataGrouped = mydata.GroupBy("Shop", "it").Select("new (it.Key as Shop, it as Albums)");
foreach (dynamic group in mydataGrouped)
{
foreach (dynamic album in group.Albums)
{
Console.WriteLine(album.Author);
}
}
Solution 2
You may construct the group by expression dynamically or give a try to this Dynamic LINQ library presented on ScottGu's page:
http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx
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Marcel
I am a passionate and experienced software engineer based in London. www.marcelheeremans.com
Updated on July 04, 2022Comments
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Marcel almost 2 years
I am trying to do a GroupBy using Dynamic LINQ but have trouble getting it to work.
This is some sample code illustrating the problem:
List<dtoMyAlbum> listAlbums = new List<dtoMyAlbum>(); for (int i = 0; i < 5000; i++) { dtoMyAlbum album = new dtoMyAlbum { Author = "My Author", BookID = i, CurrSymbol = "USD", Price = 23.23, Shop = i % 3 == 0 ? "TESCO" : "HMV" }; listAlbums.Add(album); } IQueryable<dtoMyAlbum> mydata = listAlbums.AsQueryable(); int count = mydata.Count(); //var mydataGrouped = mydata.GroupBy(a => a.Shop); // <-- this works well (but is not dynamic....) var mydataGrouped = mydata.GroupBy("Shop"); // <-- does not compile but is kind of what I want... foreach (var group in mydataGrouped) { //count = group.Count(); }
I realise that I am missing the 'elementSelector' in the GroupBy overload but all I want to do is to end up with (in this case) two sets of dtoMyAlbum objects so I wish to select ALL elements for all sets...
How would I go about this?
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Marcel over 10 yearsThat is brilliant and seems to work but how would I iterate over the resulting groups?
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Bassam Alugili over 10 yearsjust use ToList(); and If you have a new type than you have to select them new {shop... etc.}
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Marcel over 10 yearsNot sure I understand - the groups are of type IGrouping - there is nowhere an option to do a ToList...
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Marcel over 10 yearsThat works well thanks, but seems pretty inefficient since I have to create new List<T>'s out of the result in order to pass them on. Is there another way (like ToList<>)?
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Marcel over 10 yearsgot pointed by someone to stackoverflow.com/questions/12396813/…
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Raj over 8 yearsThanks. That was helpful.