jqgrid footervalue not correct if rows is empty - asp.net

Question

I have a jqgrid (ver 4.6.0.0), I show a grant total on footer of a amount column. If user insert a new row or delete a row, it should recalculate the total amount, and show it on footer. It works fine until the grid is empty(no any rows), I mean if user delete the last row on grid, the code still calculate the correct amount ( 0 ), but the footer still show the total amount it was, not 0.
Here is my code:
protected void Jqgrid1_DataRequested(object sender, JQGridDataRequestedEventArgs e)
{
DataSet _ds = (DataSet)Session["myApplicationForm"];
DataTable dt1 = _ds.Tables[1] as DataTable;
CalcVoucherAmt(dt1);
}
private void CalcVoucherAmt(DataTable _dt)
{
decimal amtSum = 0;
foreach (DataRow dr in _dt.Rows)
{
amtSum += obj2decimal(dr["DETAIL_AMT"]);
}
Jqgrid1.Columns.FromDataField("DETAIL_AMT").FooterValue = amtSum.ToString();
}
protected void Jqgrid1_RowAdding(object sender, Trirand.Web.UI.WebControls.JQGridRowAddEventArgs e)
{
DataSet _ds = (DataSet)Session["myApplicationForm"];
DataTable dt1 = _ds.Tables[1] as DataTable;
dt1.PrimaryKey = new DataColumn[] { dt1.Columns["DATA_SEQ"] };
DataRow row = dt1.NewRow();
row["UNIQ_KEY"] = System.Guid.NewGuid().ToString();
row["DETAIL_AMT"] = amt; //user input
dt1.Rows.InsertAt(row, dt1.Rows.Count);
Session["myApplicationForm"] = _ds;
Jqgrid1.DataSource = dt1;
Jqgrid1.DataBind();
}
protected void Jqgrid1_RowEditing(object sender, Trirand.Web.UI.WebControls.JQGridRowEditEventArgs e)
{
DataSet _ds = (DataSet)Session["myApplicationForm"];
DataTable dt1=_ds.Tables[1] as DataTable;
dt1.PrimaryKey = new DataColumn[] { dt1.Columns["DATA_SEQ"] };
DataRow rowEdited = dt1.Rows.Find(e.RowKey);
rowEdited["DETAIL_AMT"] = amt; //user input
Session["myApplicationForm"] = _ds;
Jqgrid1.DataSource = dt1;
Jqgrid1.DataBind();
}
protected void Jqgrid1_RowDeleting(object sender, JQGridRowDeleteEventArgs e)
{
DataSet _ds = (DataSet)Session["myApplicationForm"];
DataTable dt1 = _ds.Tables[1] as DataTable;
dt1.PrimaryKey = new DataColumn[] { dt1.Columns["DATA_SEQ"] };
DataRow rowToDelete = dt1.Rows.Find(e.RowKey);
if (rowToDelete != null)
dt1.Rows.Remove(rowToDelete);
}
and in aspx, the code is
<cc1:JQGrid ID="Jqgrid1" runat="server" Height="100%" Width="100%" AutoWidth="true" PagerSettings-PageSizeOptions="[]"
OnRowAdding="Jqgrid1_RowAdding"
OnRowEditing="Jqgrid1_RowEditing"
OnDataRequested="Jqgrid1_DataRequested"
OnRowDeleting="Jqgrid1_RowDeleting">
</cc1:JQGrid>
any idea?

Answer 1

Why you decide that jqGrid "should recalculate the total amount" automatically? If you insert a row using or delete a row you can specify callback which will be called at the end of Add/Delete operation. Inside of the callback you can use getCol to recalculate the total amount and to use footerData to set new value in the footer.
Alternatively you can trigger reloadGrid which will sort new data correctly, recalculate the total amount and to place it on the footer row. Both ways will work.
The code which you posted seems to have mo relation to jqGrid. It don't show which editing mode and how you use to Add/Delete rows. So I can't give you more detailed implementation tips.