I see code like the following a lot:
protected void GridView1_RowCreated(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.Header)
if (String.Empty != this.GridView1.SortExpression)
AddSortImage(e.Row);
}
The problem with this is that it fires for each row in the GridView, slowing performance. A better way is the following, which only fires once per GridView binding:
protected void GridView1_DataBound(object sender, EventArgs e)
{
if (String.Empty != this.GridView1.SortExpression)
AddSortImage(GridView1.HeaderRow);
}
The supporting methods are:
void AddSortImage(GridViewRow headerRow)
{
int iCol = GetSortColumnIndex();
if (-1 == iCol)
return;
// Create the sorting image based on the sort direction.
Image sortImage = new Image();
if (SortDirection.Ascending == this.GridView1.SortDirection)
{
sortImage.ImageUrl = @"~\Images\BlackDownArrow.gif";
sortImage.AlternateText = "Ascending Order";
}
else
{
sortImage.ImageUrl = @"~\Images\BlackUpArrow.gif";
sortImage.AlternateText = "Descending Order";
}
// Add the image to the appropriate header cell.
headerRow.Cells[iCol].Controls.Add(new LiteralControl(" "));
headerRow.Cells[iCol].Controls.Add(sortImage);
}
public int GetSortColumnIndex()
{
// Iterate through the Columns collection to determine the index
// of the column being sorted.
foreach (DataControlField field in GridView1.Columns)
{
if (field.SortExpression == this.GridView1.SortExpression)
{
return this.GridView1.Columns.IndexOf(field);
}
}
return -1;
}
I see code like the following a lot:
protected void GridView1_RowCreated(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.Header)
if (String.Empty != this.GridView1.SortExpression)
AddSortImage(e.Row);
}The problem with this is that it fires for each row in the GridView slowing performance. A better way is the following, which only fires once per GridView binding:
protected void GridView1_DataBound(object sender, EventArgs e)
{
if (String.Empty != this.GridView1.SortExpression)
AddSortImage(GridView1.HeaderRow);
}
The supporting methods are:
void AddSortImage(GridViewRow headerRow)
{
int iCol = GetSortColumnIndex();
if (-1 == iCol)
return;
// Create the sorting image based on the sort direction.
Image sortImage = new Image();
if (SortDirection.Ascending == this.GridView1.SortDirection)
{
sortImage.ImageUrl = @"~\Images\BlackDownArrow.gif";
sortImage.AlternateText = "Ascending Order";
}
else
{
sortImage.ImageUrl = @"~\Images\BlackUpArrow.gif";
sortImage.AlternateText = "Descending Order";
}
// Add the image to the appropriate header cell.
headerRow.Cells[iCol].Controls.Add(new LiteralControl(" "));
headerRow.Cells[iCol].Controls.Add(sortImage);
}
public int GetSortColumnIndex()
{
// Iterate through the Columns collection to determine the index
// of the column being sorted.
foreach (DataControlField field in GridView1.Columns)
{
if (field.SortExpression == this.GridView1.SortExpression)
{
return this.GridView1.Columns.IndexOf(field);
}
}
return -1;
}