dynamic datagrid

[cindy]

I am sorry I can't tell if the first message posted, sorry if this is a
repost truly.


I have a dynamic datagrid. I have custom classes for the controls

public class CreateEditItemTemplateDDL : ITemplate {
DataTable dtBind;
string strddlName;
string strSelectedID;
string strDataValueField;
string strDataTextField;

public CreateEditItemTemplateDDL(string DDLName,string DataValueField,string

DataTextField,string SelectedValueField,DataTable DDLSource){
dtBind=DDLSource;
strDataValueField=DataValueField;
strDataTextField=DataTextField;
strSelectedID=SelectedValueField;
this.strddlName=DDLName;}
public void InstantiateIn(Control objContainer){
DropDownList ddl = new DropDownList();
ddl.DataBinding+=new EventHandler(ddl_DataBinding);
objContainer.Controls.Add(ddl);}

private void ddl_DataBinding(object sender, EventArgs e){
DropDownList ddl= (DropDownList)sender;
ddl.ID=strddlName;
ddl.DataSource=dtBind;
ddl.DataValueField=strDataValueField;
ddl.DataTextField=strDataTextField;
for (int i=0;i<dtBind.Rows.Count;i++){
if(strSelectedID == dtBind.Rows[strDataValueField].ToString())

{
ddl.SelectedIndex=i; }
}}}

I do a creategrid and display the grid from dataset after load
I can get the selected values from hidden fields.

MY Problem

How can the user select a new value in the first drop down list and change
the

range of possible values in the second drop down list, select the new values

and then update the row back to the database. (I know how to do the update
it

is the display of a new range of values in the second list have the first
list

has an index changed event.) Example the first list from database has 2
values

fruit and vegetable, vegetable is selected for the database row in edit mode

and in the second list where tomato was selected (choices might be lettuce or

tomato.) the choice violates database integrity data needs to have been

repopulated to show the fruit range of choices. User selects value fruit
first

list, I need the second list to repopulate with range of fruits example
orange

and grape, new row at top inserted value is 0 says pick a fruit. I started

with creating an ascx control which is a dropdown list. I can get this
control

to drop on an aspx form with a label, choose a new value and based on event

handler for index changed in the ascx return the new value based on the index

selected to the form label showing the value for the selected list array. I

next put this ascx in the datagrid with

ITemplate temp= Page.LoadTemplate("Controls/StoreSelector.ascx");
tcl5.EditItemTemplate = temp;
//the control id is storeList

I had to first change to ascx code to get this to work, in the databind on
page

load in the ascx I can not do a check for (!(Page.IsPostBack)) because the
list

is displayed only when the row is clicked for edit so if I did that the list

does not populate with any values.

Next how do I get the dropdown list selected value to be the value from the

datagrid underlying datatable for the row. What am I doing inside the ascx

(what public exposure) that I can access the property in the event

itemdatabound of the datagrid to set the selected value? I always get the

first item in the dropdownlist.
I tried putting in the ascx code behind

public string SelectedValue{
get{return storeList.SelectedValue;}
set{storeList.SelectedValue = value;}
}

In the aspx code behind I try to pass a value from datagrid datatable for the

row

private void dgRt2_ItemDataBound(object sender, DataGridItemEventArgs e){
DataGrid dg = (DataGrid)sender;
int cnt = e.Item.ItemIndex + (dg.PageSize * dg.CurrentPageIndex);
DataTable dtBound = (DataTable)dg.DataSource;

if(e.Item.ItemType==ListItemType.EditItem) {
string strZone = dtBound.Rows[cnt]["zonelu"].ToString();
SISWebAdmin.Controls.StoreSelector ddlz =

(SISWebAdmin.Controls.StoreSelector)e.Item.Cells[0].FindControl("storeList");
ddlz.SelectedValue = strZone;}


When I debug I pass the line where I do a cast of the control to the ascx and

do a find control in the datagrid
I have the correct string in the strZone variable from the datatable that I

need to set to but I error on the line ddlz .SelectedValue = strZone

I get the follow error message and stack trace

e1 at SISWebAdmin.WebForm1.dgRt2_ItemDataBound(Object sender,

DataGridItemEventArgs e) in c:\program files\common files\microsoft
shared\web

server extensions\60\template\layouts\siswebadmin\webform1.aspx.cs:line 804
at

System.Web.UI.WebControls.DataGrid.OnItemDataBound(DataGridItemEventArgs e)
at

System.Web.UI.WebControls.DataGrid.CreateItem(Int32 itemIndex, Int32

dataSourceIndex, ListItemType itemType, Boolean dataBind, Object dataItem,

DataGridColumn[] columns, TableRowCollection rows, PagedDataSource

pagedDataSource) at

System.Web.UI.WebControls.DataGrid.CreateControlHierarchy(Boolean

useDataSource) at

System.Web.UI.WebControls.BaseDataList.OnDataBinding(EventArgs e) at

System.Web.UI.WebControls.BaseDataList.DataBind() at

SISWebAdmin.WebForm1.fillgrid(String sFullname, String strZone, String
strArea,

String strTitle) in c:\program files\common files\microsoft shared\web server

extensions\60\template\layouts\siswebadmin\webform1.aspx.cs:line 368Object

reference not set to an instance of an object.SISWebAdmin


For weeks I could not get into news groups, account issues I don't know what

and have posted everywhere, no replies. If there is a better way tell me, I

have 3 dropdowns in dynamic grid that basically depend on each other for
their

range of values. The user in edit mode would theorectically changed the
first

range and need new value selection for second then third before the row can
be