DevForce 2010: Dynamic Group By and Count

Dynamic Group By and Count

Printed From: IdeaBlade
Category: DevForce
Forum Name: DevForce 2010
Forum Discription: For .NET 4.0
URL: http://www.ideablade.com/forum/forum_posts.asp?TID=2960
Printed Date: 13-May-2026 at 6:18pm

Topic: Dynamic Group By and Count

Posted By: BringerOD
Subject: Dynamic Group By and Count
Date 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();

}

Replies:

Posted By: BringerOD
Date 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 - 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

Posted By: DenisK
Date 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);

Posted By: BringerOD
Date 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