LINQ to DataSet case insensitive group by

Question

I have a data table and I want to perform a case insensitive group by over a column of data table (say Column1 of type string). I observed that normally LINQ to DataSet perform case sensitive comparison. For example if Column1 is having two values say Test and test, after applying group by it returns two seperate rows with values Test and test. The query is as follows:

var countGroupQuery = from table in dataTable.AsEnumerable()
                      group table by table.Field<string>(Column1) into groupedTable
                      select new
                      {
                          value = groupedTable.Key,
                          count = groupedTable.Count()
                      };

so, is there any method exist to perform case in-sensitive group by so that in above example I get only one row with one value either Test or test? Also I dont want to use ToUpper or ToLower methods because it actually changes the values to either upper case or lower case.

group table by table.Field<string>(Column1).ToUpper() into groupedTable

Thanks,

Answer 1

This MSDN article has some information on datasets and case sensitivity..

You can control the case sensitivity of filtering, searching, and sorting by setting the dataset's CaseSensitive property.

Answer 2

You can't do this from a query expression, but you can do it with dot notation:

var query = dataTable.AsEnumerable()
                     .GroupBy(x => table.Field<string>(Column1),
                              StringComparer.InvariantCultureIgnoreCase)
                     .Select(groupedTable => new
                             {
                                 value = groupedTable.Key,
                                 count = groupedTable.Count()
                             });

You can even use a more complicated overload of GroupBy to do it in one call:

var query = dataTable.AsEnumerable()
                     .GroupBy(x => table.Field<string>(Column1),
                              (key, group) => { value = key, 
                                                count = group.Count() },
                              StringComparer.InvariantCultureIgnoreCase));

Obviously that's using the invariant culture - you could also use the current culture or ordinal rules.