Reorder records in a dataset

Question

I am trying to sort records in a dataset according to user preferences. I add a button (move up) to increase the selected record by 1 line above, and this is what I have done so far:

private void btnMoveUp_Click(object sender, EventArgs e) { int index = dataGridView1.CurrentRow.Index; if (index >= 1) { var temp = dsWinners.Tables[0].Rows[index]; dsWinners.Tables[0].Rows[index].Delete(); dsWinners.Tables[0].Rows.InsertAt(temp, index - 1); dsWinners.Tables[0].AcceptChanges(); dataGridView1.DataSource = dsWinners.Tables[0]; } } 

but I get the error "This row already belongs to this table." on this line:

 dsWinners.Tables[0].Rows.InsertAt(temp, index - 1); 

I know that I need to use ImportRow (temp) instead of InsertAt (temp, index-1), but the problem is that I do not know how to import it to the desired position. I looked int to THIS , but like the guy who answered the question, he says "Its sloppy and halfway."

Anyway, can I solve this problem? and if so, how can I do this?

Answer 1

Try the following:

 var temp = dsWinners.Tables[0].Rows[index]; \\getting row var newrow = dsWinners.Tables[0].NewRow(); \\ creating new row to insert newrow.ItemArray = temp.ItemArray; \\ copying data from old to new row dsWinners.Tables[0].Rows[index].Delete(); \\deleting old row. dsWinners.Tables[0].Rows.InsertAt(newrow, index - 1); \\ adding new row. 

Answer 2

Instead of deleting a row and adding it again to another position, you can add a column to the table containing the position.

You did not bind the DataGridView to the table itself, but to the DataView, which is sorted by the "Position" column.

In the DataGridView you must add all the columns except the position so that the position does not display.

When you move a row up or down, you change the value of the Position cell with the previous or next row, respectively. Because the DataView is sorted by position, the move is immediately displayed in the DataView.

The following console application shows the basic steps:

 void Main() { // Create a new DataTable DataTable tbl = GetData(); // Add Position column and initialize it tbl.Columns.Add("Position", typeof(int)); for(int i = 0; i < tbl.Rows.Count; i++) tbl.Rows[i]["Position"] = i; PrintView("Original", tbl.DefaultView); // Create a view that is sorted by the Position column var view = new DataView(tbl); view.Sort = "Position"; PrintView("Sorted", view); // No change as the rows are in original order anyway // Move a row SwapPositions(view, 0, 1); // Move first row down PrintView("Swapped", view); } private DataTable GetData() { DataTable tbl = new DataTable(); tbl.Columns.Add("Value", typeof(string)); for(int i = 0; i < 3; i++) tbl.Rows.Add("Text " + i.ToString()); return tbl; } private void PrintView(string header, DataView view) { Console.WriteLine(header); foreach(DataRowView row in view) Console.WriteLine("{0}\t{1}", row["Position"], row["Value"]); } private void SwapPositions(DataView view, int rowIndex1, int rowIndex2) { // Save rows as the change in the Position column is reflected immediately DataRowView row1 = view[rowIndex1]; DataRowView row2 = view[rowIndex2]; // Now swap positions var saveValue = row1["Position"]; row1["Position"] = row2["Position"]; row2["Position"] = saveValue; view.Table.AcceptChanges(); } 

Output:

 Original 0 Text 0 1 Text 1 2 Text 2 Sorted 0 Text 0 1 Text 1 2 Text 2 Swapped 0 Text 1 1 Text 0 2 Text 2 

Answer 3

You can try one more thing. Try replacing the code

 var temp = dsWinners.Tables[0].Rows[index]; 

with the following ::

 var temp = dsWinners.Tables[0].NewRow(); temp.ItemArray = dsWinners.Tables[0].ItemArray; 

This creates a new line and moves it to the specified position instead of switching the existing one.