Linq Dynamic group by statement

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I have datatable with 3 cols ( carType, colour, owner). Query below is grouping on 2 cols ( carType, colour).My question is how can i make the grouping portion more dynamic by using reflection. my idea is add the grouping col in to array, then use the reflection on the query grouping part. however i was struck at the reflection..

XML

var gcols = new string[] { "CarType", "Colour" };
           var result = dt.AsEnumerable()
                                .GroupBy(x => new
                                {
                                    carType = x.Field<string>("carType"),
                                    colour = x.Field<string>("colour")
                                })
                                .Select(x => new
                                {
                                    CarType = x.Key.carType,
                                    Colour = x.Key.colour,
                                    count = x.Count()
                                })
                               .OrderBy(x => x.CarType).ToList();

Posted 15-Apr-13 4:05am

Tina Ng

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Nicolas Lips · Answer 1 · 2014-02-04T00:19:00

The .QueryByCube() function provided by AdaptiveLINQ (www.adaptivelinq.com) is designed to make this kind of query (multi-dimesensional analysis query).
It doesn't use dynamic LINQ but transforms the query based on grouping criteria expressed by the selection.

For example, you can write:

"Count by type":

C#

dt.QueryByCube(yourCubeDefinition)
  .Select(x => new {
    Type = x.Type,
    Count = c.Count
  })

"Count by color":

C#

dt.QueryByCube(yourCubeDefinition)
  .Select(x => new {
    Color = x.Color,
    Count = c.Count
  })

"Count by type and color":

C#

dt.QueryByCube(yourCubeDefinition)
  .Select(x => new {
    Type = x.Type,
    Color = x.Color,
    Count = c.Count
  })

Faisal(mfrony) · Answer 2 · 2013-04-15T05:45:00

XML

var gcols = new string[] { "CarType", "Colour" };
         var result = dt.AsEnumerable()
                              .GroupBy(x => new[]
                              {
                                  x.Field<string>(gcols.FirstOrDefault()),
                                  x.Field<string>(gcols.LastOrDefault())
                              })
                              .Select(x => new
                              {
                                  CarType = x.Key.Where(p=>p.Contains(gcols.FirstOrDefault())),
                                  Colour = x.Key.Where(p=>p.Contains(gcols.LastOrDefault())),
                                  count = x.Count()
                              })
                             .OrderBy(x => x.CarType).ToList();

Linq Dynamic group by statement

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