Copy specific rows from One DataTable to another DataTable using LINQ

Question

Below is my code in which I am trying to copy 3 Columns "BATCH NUM", "QTY" and "PROD ID" from one to another. Problem is that "BATCH NUM", "QTY" are copied but "PROD ID" column is not copied.

var newDt = dt.AsEnumerable()
              .GroupBy(r => r.Field<string>("BATCH NUM"))
              .Select(g =>
              {
                  var row = dt.NewRow();

                  row["BATCH NUM"] = g.Key;
                  row["QTY"] = g.Sum(r => Convert.ToInt32(r.Field<string>("QTY")) + Convert.ToInt32(r.Field<string>("BONUS")));
                  row["PROD ID"] = g.Select(r => r.Field<string>("PROD ID"));
                  return row;
              }).CopyToDataTable();

How can I copy "PROD ID" to DataTable?

Answer 1

Using Select on PROD ID means you are trying to store collection of string in a column which supports storing a string value. This will by default calls ToString method on a collection and results in System.Linq... string value in a column.

You want to use appropriate function to get all values in the column:

var newDt = dt.AsEnumerable()
              .GroupBy(r => r.Field<string>("BATCH NUM"))
              .Select(g =>
              {
                  var row = dt.NewRow();

                  row["BATCH NUM"] = g.Key;
                  row["QTY"] = g.Sum(r => Convert.ToInt32(r.Field<string>("QTY")) + Convert.ToInt32(r.Field<string>("BONUS")));
                  row["PROD ID"] = String.Join(",", g.Select(x => x.Field<string>("PROD ID")).Distinct());
                  return row;
              }).CopyToDataTable();