Linq Implementation With Dynamic GroupBy Clause - linq

Question

In the bellow Linq Statement, i am facing an error in "Select" while trying to fetch, datatable field like "ID" and assign it to row["ID"].
//row["ID"] = g.Field<decimal>("ID");
Error Message:
System.Linq.IGrouping<string,System.Data.DataRow> does not contain a definition for 'Field'
var x = groupedDataRow
.AsEnumerable()
.Select(g =>
{
var row = dataTable.NewRow();
//row["ID"] = g.Field<decimal>("ID");
row["AMT"] = g.Sum(r => r.Field<decimal>("AMT"));
row["PERCENTAGE"] = g.Sum(r => r.Field<decimal>("PERCENTAGE"));
return row;
}).CopyToDataTable();
How retrieve datatable field like "ID" so that it could be assigned to row["ID"] in the Select statement?
Linq Example
public class Program
{
static StringBuilder stringBuilder = new StringBuilder();
public static String GroupData(DataRow dataRow)
{
String[] columnNames = new[] {"ID","COL1", "COL2"};
stringBuilder.Remove(0, stringBuilder.Length);
foreach (String column in columnNames)
{
stringBuilder.Append(dataRow[column].ToString());
}
return stringBuilder.ToString();
}
public static void Main()
{
DataTable dataTable = new DataTable("MyTable");
DataColumn dc2 = dataTable.Columns.Add("ID", typeof(decimal));
dataTable.Columns.Add("AMT", typeof(decimal));
dataTable.Columns.Add("PERCENTAGE", typeof(decimal));
dataTable.Columns.Add("COL1", typeof(String));
dataTable.Columns.Add("COL2", typeof(String));
dataTable.Rows.Add(000, 400,100,"sss","vvv");
dataTable.Rows.Add(888, 400, 100,"qqq","fff");
dataTable.Rows.Add(000, 300, 100,"eee","aaa");
dataTable.Rows.Add(000, 300, 100,"eee","aaa");
dataTable.Rows.Add(000,400,100,"sss","vvv");
EnumerableDataRowList<DataRow> enumerableRowCollection = new EnumerableDataRowList<DataRow>(dataTable.Rows);
Func<DataRow, String> groupingFunction = GroupData;
var groupedDataRow = enumerableRowCollection.GroupBy(groupingFunction);
var x = groupedDataRow.AsEnumerable()
.Select(g =>
{
var row = dataTable.NewRow();
//row["ID"] = g.Field<decimal>("ID");
row["AMT"] = g.Sum(r => r.Field<decimal>("AMT"));
row["PERCENTAGE"] = g.Sum(r => r.Field<decimal>("PERCENTAGE"));
return row;
}).CopyToDataTable();
foreach(DataRow row in x.Rows)
{
Console.WriteLine(row["ID"].ToString() + " " + row["COL1"].ToString() + " " + row["COL2"].ToString() + " " + row["AMT"].ToString() + " " + row["PERCENTAGE"].ToString()) ;
}
}
class EnumerableDataRowList<T> : IEnumerable<T>, IEnumerable
{
IEnumerable dataRows;
internal EnumerableDataRowList(IEnumerable items)
{
dataRows = items;
}
IEnumerator<T> IEnumerable<T>.GetEnumerator()
{
foreach (T dataRow in dataRows)
yield return dataRow;
}
IEnumerator IEnumerable.GetEnumerator()
{
IEnumerable<T> iEnumerable = this;
return iEnumerable.GetEnumerator();
}
}

Answer 1

It's because g is an IGrouping which doesn't have a Field member.
You could maybe try something like:
var x = groupedDataRow.AsEnumerable()
.Select(g =>
{
var row = dataTable.NewRow();
row["ID"] = g.Select(r => r.Field<decimal>("ID")).FirstOrDefault();
row["AMT"] = g.Sum(r => r.Field<decimal>("AMT"));
row["PERCENTAGE"] = g.Sum(r => r.Field<decimal>("PERCENTAGE"));
return row;
}).CopyToDataTable();
or
var x = groupedDataRow.AsEnumerable()
.Select(g =>
{
var row = dataTable.NewRow();
row["ID"] = g.First().Field<decimal>("ID");
row["AMT"] = g.Sum(r => r.Field<decimal>("AMT"));
row["PERCENTAGE"] = g.Sum(r => r.Field<decimal>("PERCENTAGE"));
return row;
}).CopyToDataTable();
It should be safe to use g.First() because a group is only a group if it contains any items.