Demonstration of Row Swapping in a Grid View

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Introduction

Once I came across a situation where the client wanted to swap the rows in a GridView. I will show a sample example of doing the same.

Straight to the Program

The datasource is basically a datatable with two columns viz. Name, Address:

DataTable dtsource = new DataTable();

//Adding columns to datatable
dtsource.Columns.Add("Name");
dtsource.Columns.Add("Address");

dtsource.Rows.Add("Name1", "Address1");
dtsource.Rows.Add("Name2", "Address2");
dtsource.Rows.Add("Name3", "Address3");
dtsource.Rows.Add("Name4", "Address4");
dtsource.Rows.Add("Name5", "Address5");
dtsource.Rows.Add("Name6", "Address6");
dtsource.Rows.Add("Name7", "Address7");
dtsource.Rows.Add("Name8", "Address8");
dtsource.Rows.Add("Name9", "Address9");
dtsource.Rows.Add("Name10", "Address10");

I consume the same for the GridView at the page load event.

I wrote the swapping logic in the Row Command event since it is the event that gets fired when a control (e.g. Button) is clicked that resides inside the GridView. 

Obviously, the Button’s CommandName as well as the Command Argument need to be set. 

In this case, the CommandName is set to Up & Down respectively while I pass the grid’s row id in the Command Argument.

CommandName="Up" CommandArgument=<%# Container.DataItemIndex %>

The Swap method whose signature is Swap(int rowid, string option) does the row swapping:

/// <summary>
/// Function name: Swap
/// Purpose: Swaps the grid's row
/// </summary>
/// current row id of the grid
/// Up or Down
private void Swap(int rowid, string option)
{
    //Logic
    //e.g.
    // temp  = val1
    // val1 = val2
    //val2 = temp

    if (option == "UP")
    {
        for (int i = 0; i <= 1; i++)
        {
            string temp = grdRowMovementDemo.Rows[rowid - 1].Cells[i].Text;
            grdRowMovementDemo.Rows[rowid - 1].Cells[i].Text = 
			grdRowMovementDemo.Rows[rowid].Cells[i].Text;
            grdRowMovementDemo.Rows[rowid].Cells[i].Text = temp;
        }
    }
    else
    {
        for (int i = 0; i <= 1; i++)
        {
            string temp = grdRowMovementDemo.Rows[rowid].Cells[i].Text;
            grdRowMovementDemo.Rows[rowid].Cells[i].Text = 
			grdRowMovementDemo.Rows[rowid + 1].Cells[i].Text;
            grdRowMovementDemo.Rows[rowid + 1].Cells[i].Text = temp;
        }
    }
}

I wrote the calling function in the RowCommand event of the GridView. It is as under:

int rowid = Convert.ToInt32(e.CommandArgument);

if (e.CommandName == "Up")
{
    if (rowid > 0) // Rowid == 0 indicates that the top most row is reached
    Swap(rowid, "UP");
}

if (e.CommandName == "Down")
{
    if (rowid != grdRowMovementDemo.Rows.Count - 1)	// the bottom most row
						// is reached
    Swap(rowid, "DOWN");
}

Conclusion

I have shown one of the ways by which we can achieve the row movement in the GridView. Any better suggestion/solution is always welcome.

History

• 24^th May, 2009: Initial post