Gridview row editing - dynamic binding to a DropDownList

Question

I'm trying to get an ASP.NET 3.5 GridView to show a selected value as string when being displayed, and to show a DropDownList to allow me to pick a value from a given list of options when being edited. Seems simple enough?

My gridview looks like this (simplified):

<asp:GridView ID="grvSecondaryLocations" runat="server"                DataKeyNames="ID" OnInit="grvSecondaryLocations_Init"                OnRowCommand="grvSecondaryLocations_RowCommand"                OnRowCancelingEdit="grvSecondaryLocations_RowCancelingEdit"               OnRowDeleting="grvSecondaryLocations_RowDeleting"               OnRowEditing="grvSecondaryLocations_RowEditing"                OnRowUpdating="grvSecondaryLocations_RowUpdating"  > <Columns>     <asp:TemplateField>          <ItemTemplate>               <asp:Label ID="lblPbxTypeCaption" runat="server"                                   Text='<%# Eval("PBXTypeCaptionValue") %>' />          </ItemTemplate>          <EditItemTemplate>                       <asp:DropDownList ID="ddlPBXTypeNS" runat="server"                                 Width="200px"                                 DataTextField="CaptionValue"                                 DataValueField="OID" />          </EditItemTemplate>     </asp:TemplateField> </asp:GridView> 

The grid gets displayed OK when not in editing mode - the selected PBX type shows its value in the asp:Label control. No surprise there.

I load the list of values for the DropDownList into a local member called _pbxTypes in the OnLoad event of the form. I verified this - it works, the values are there.

Now my challenge is: when the grid goes into editing mode for a particular row, I need to bind the list of PBX's stored in _pbxTypes.

Simple enough, I thought - just grab the drop down list object in the RowEditing event and attach the list:

protected void grvSecondaryLocations_RowEditing(object sender, GridViewEditEventArgs e) {     grvSecondaryLocations.EditIndex = e.NewEditIndex;      GridViewRow editingRow = grvSecondaryLocations.Rows[e.NewEditIndex];      DropDownList ddlPbx = (editingRow.FindControl("ddlPBXTypeNS") as DropDownList);     if (ddlPbx != null)     {         ddlPbx.DataSource = _pbxTypes;         ddlPbx.DataBind();     }      .... (more stuff) } 

Trouble is - I never get anything back from the FindControl call - seems like the ddlPBXTypeNS doesn't exist (or can't be found).

What am I missing?? Must be something really stupid.... but so far, all my Googling, reading up on GridView controls, and asking buddies hasn't helped.

Who can spot the missing link? ;-)

Answer 1

Quite easy... You're doing it wrong, because by that event the control is not there:

protected void gv_RowDataBound(object sender, GridViewRowEventArgs e) {     if (e.Row.RowType == DataControlRowType.DataRow &&          (e.Row.RowState & DataControlRowState.Edit) == DataControlRowState.Edit)     {          // Here you will get the Control you need like:         DropDownList dl = (DropDownList)e.Row.FindControl("ddlPBXTypeNS");     } } 

That is, it will only be valid for a DataRow (the actually row with data), and if it's in Edit mode... because you only edit one row at a time. The e.Row.FindControl("ddlPBXTypeNS") will only find the control that you want.