Table of Contents
Table of Contents
Implementing Sorting

Enable Sortting

To enable sortting, the following properties must be set correctly:

Property Required Remarks
GridColumn.AllowSort Required Sortting can be enabled on each individual column. Set a column's AllowSort to True to enable sorting on that column.
ColumnHeaderAscImage Optional Optional image to be displayed on a column header to indicate items are sorted in ascending order.
ColumnHeaderDescImage Optional Optional image to be displayed on a column header to indicate items are sorted in descending order.
ColumnHeaderSortImageOffset Optional The sort image offset relative to the right edge of the column header. The default value is 20. You may need to adjust this value to fit your design.

You can also set one of the grid column's SortOrder to either Ascending or Descending to indicate the grid can be sorted.

Handling Sorting Event

EO.Web Grid automatically handles sorting event in client mode. When the grid is in server mode or callback mode, you must handle ColumnSort event. Typically you would repoulate the grid with the new sort order. The following code demonstrates how to repopulate the grid inside ColumnSort event:
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//Populate the grid
private void LoadGridData(EO.Web.GridColumn sortColumn)
{
    //Deciding sort orders
    string sortField = "PostedAt";
    string sortOrder = "DESC";
    if (sortColumn != null)
    {
        sortField = sortColumn.DataField;
        sortOrder = sortColumn.SortOrder == EO.Web.SortOrder.Ascending ? "ASC" : "DESC";
    }
    string sortOrderReverse = sortOrder == "ASC" ? "DESC" : "ASC";

    using (DemoDB db = new DemoDB())
    {    
        //Only fetch data for the current page from the database.
        //This is achieved by utilizing the "TOP n" clause supported
        //by Access/SQL Server database combined with sort orders.
        //Similar but different mechanism maybe needed with other
        //type of database engines.
        string sql1 = string.Format(
            "SELECT TOP {0} * FROM Topics ORDER BY {1} {2}", 
            (Grid1.CurrentPage + 1) * Grid1.PageSize, sortField, sortOrder);

        string sql2 = string.Format(
            "SELECT TOP {0} * FROM ({1}) ORDER BY {2} {3}",
            Grid1.PageSize, sql1, sortField, sortOrderReverse);

        string sql3 = string.Format(
            "SELECT * FROM ({0}) ORDER BY {1} {2}",
            sql2, sortField, sortOrderReverse);

        OleDbDataReader reader = db.ExecuteReader(sql3);
        Grid1.DataSource = reader;
        Grid1.DataBind();
    }
}

private void Grid1_ColumnSort(object sender, EO.Web.GridColumnEventArgs e)
{
    LoadGridData(e.Column);
}