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Dynamic Group By and Count
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BringerOD View Drop Down
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Joined: 27-Aug-2010
Location: USA
Posts: 35 		Post Options Post Options   Quote BringerOD Quote  Post ReplyReply Direct Link To This Post Topic: Dynamic Group By and Count
    Posted: 15-Sep-2011 at 9:41am
Does anyone know how to get a groupby count from a dynamic query?  I can group by a field, I just can't get it's count without pulling all the records down.   I just want the group field and how many there are.

This works, but only returns the key.
var selector = new AnonymousProjectionSelector().Combine("Key");


This does not.  I was only guessing anyway.
var selector = new AnonymousProjectionSelector().Combine("Key").Combine("Key.Count","Count");


Code

      public void ReadDistinctValuesAndCounts(object sender, QueryGroupsEventArgs e)
      {
         var query = BuildWhereClause(e.CollectionView, e.GroupPath, _baseQuery);
         query = BuildSortClause(e.CollectionView, query);
         var groupByField = e.ChildGroupPropertyName;
         var groupBy = new ProjectionSelector(groupByField);
   
var selector = new AnonymousProjectionSelector().Combine("Key");
         ITypedEntityQuery groupByQuery = query.GroupBy(groupBy).Select(selector);
         
         var result = groupByQuery.Execute();

       }
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BringerOD View Drop Down
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Posts: 35 		Post Options Post Options   Quote BringerOD Quote  Post ReplyReply Direct Link To This Post Posted: 15-Sep-2011 at 3:28pm

I figured out a way to do it using this

http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx

It’s a way to do linq queries dynamically.

var result = query.GroupBy(“FieldToGroup”,"it").Select("new(Key as Name, Count() as Total)");

Bryan
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DenisK View Drop Down
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Joined: 25-Aug-2010
Posts: 715 		Post Options Post Options   Quote DenisK Quote  Post ReplyReply Direct Link To This Post Posted: 15-Sep-2011 at 8:16pm
Hi Bryan;

Is this the type of query that you want to do dynamically?

query.GroupBy(g => g.CategoryID).Select(s => new { Name = s.Key, Total = s.Count() });

if so, this is how you would do it,

var groupBySelector = new AnonymousProjectionSelector().Combine("CategoryID");
var selectSelector = new ProjectionSelector("Key", "Name").Combine("Count()", "Total");

var q0 = query.GroupBy(groupBySelector).Select(selectSelector);


Edited by DenisK - 15-Sep-2011 at 8:26pm
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BringerOD View Drop Down
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Posts: 35 		Post Options Post Options   Quote BringerOD Quote  Post ReplyReply Direct Link To This Post Posted: 15-Sep-2011 at 8:23pm
That looks like it would do it.
 
I did not think to add a select field of "Count()".
 
Thanks
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