Question

I’m getting the error ‘Object reference not set to an instance of an object.’ when trying to reference a HiddenField (lvEditProjectSteps_hdnStepStatusId for future reference) from the EditItem during the OnItemUpdating event after the Update event fires in a ListView. This only occurs on the FIRST item in the ListView. I checked the source and the HTML is being rendered properly.

ANY insight is appreciated! Thanks in advance…

Source error:

var lvEditProjectSteps_hdnStepStatusId = (HiddenField) lvEditProjectSteps.EditItem.FindControl('lvEditProjectSteps_hdnStepStatusId'); 

Here’s the aspx side of the ListView:

<asp:ListView ID='lvEditProjectSteps' runat='server'   OnItemDataBound='lvEditProjectSteps_OnItemDataBound'    OnItemUpdating='lvEditProjectSteps_OnItemUpdating'    DataSourceID='odsEditProjectStep'    DataKeyNames='Id'>   <LayoutTemplate>     <table class='standard-box-style' style='width:800px'>       <thead>         <tr>           <th>&nbsp;</th>           <th>&nbsp;</th>           <th>Created</th>           <th>Updated</th>         </tr>       </thead>       <tbody>         <asp:PlaceHolder ID='itemPlaceHolder' runat='server' />       </tbody>     </table>   </LayoutTemplate>   <ItemTemplate>     <tr>       <td style='width:50px'<%# (Container.DisplayIndex % 2 == 0)?'':' class=\'row-alternating\'' %>>         <asp:ImageButton ID='lvEditProjectSteps_btnEdit' runat='server'            ImageUrl='~/admin/images/icons/edit.gif'            AlternateText='Edit'            SkinID='interfaceButton'           CommandName='Edit' />         <asp:HiddenField ID='lvEditProjectSteps_hdnId' runat='server' Value='<%# Bind('Id')%>' />         <asp:HiddenField ID='lvEditProjectSteps_hdnStepStatusId' runat='server' Value='<%# Bind('StepStatusId')%>' />         <asp:HiddenField ID='lvEditProjectSteps_hdnStepStatusStepId' runat='server' Value='<%# Bind('StepStatus_StepId')%>' />       </td>       <td style='width:30px'<%# (Container.DisplayIndex % 2 == 0)?'':' class=\'row-alternating\'' %>><asp:Image ID='imgStatus' runat='server' /></td>       <td style='width:75px'<%# (Container.DisplayIndex % 2 == 0)?'':' class=\'row-alternating\'' %>><asp:Literal ID='litTsCreated' runat='server' /></td>       <td style='width:75px'<%# (Container.DisplayIndex % 2 == 0)?'':' class=\'row-alternating\'' %>><asp:Literal ID='litTsUpdated' runat='server' /></td>     </tr>   </ItemTemplate>   <EditItemTemplate>     <tr>       <td style='width:50px'<%# (Container.DisplayIndex % 2 == 0)?'':' class=\'row-alternating\'' %>>         <asp:ImageButton ID='lvEditProjectSteps_btnUpdate' runat='server'            ImageUrl='~/admin/images/icons/save.png'            AlternateText='Save'            SkinID='interfaceButton'           CommandName='Update'            ValidationGroup='EditProjectStepsSave' />         <asp:ImageButton ID='lvEditProjectSteps_btnCancel' runat='server'            ImageUrl='~/admin/images/icons/cancel.png'            AlternateText='Cancel'            SkinID='interfaceButton'           CommandName='Cancel' />         <asp:HiddenField ID='lvEditProjectSteps_hdnId' runat='server' Value='<%# Bind('Id')%>' />         <asp:HiddenField ID='lvEditProjectSteps_hdnStepStatusId' runat='server' Value='<%# Bind('StepStatusId')%>' />         <asp:HiddenField ID='lvEditProjectSteps_hdnStepStatusStepId' runat='server' Value='<%# Bind('StepStatus_StepId')%>' />       </td>       <td style='width:180px' colspan='3'<%# (Container.DisplayIndex % 2 == 0)?'':' class=\'row-alternating\'' %>>         <div><strong>Status</strong></div>         <div class='radiobuttonlist-status'>           <asp:RadioButtonList ID='lvEditProjectSteps_rblStatus' runat='server'                  RepeatDirection='Horizontal'                 AutoPostBack='true'             OnSelectedIndexChanged='lvEditProjectSteps_rblStatus_OnSelectedIndexChanged'>             <asp:ListItem Value='1'><img src='/images/icon/project-status/1.png' alt='Error' /></asp:ListItem>             <asp:ListItem Value='2'><img src='/images/icon/project-status/2.png' alt='In Progress' /></asp:ListItem>             <asp:ListItem Value='3'><img src='/images/icon/project-status/3.png' alt='Complete' /></asp:ListItem>           </asp:RadioButtonList>           <asp:RequiredFieldValidator ID='valRequired_lvEditProjectSteps_rblStatus' runat='server'              ControlToValidate='lvEditProjectSteps_rblStatus'              SetFocusOnError='true'             Display='Dynamic'              ErrorMessage='<br />^ required ^'              ValidationGroup='EditProjectStepsSave' />         </div>       </td>     </tr>   </EditItemTemplate> </asp:ListView> 

And the code-behind:

protected void lvEditProjectSteps_OnItemDataBound(object sender, ListViewItemEventArgs e) {   if (e.Item.ItemType == ListViewItemType.DataItem)   {     var info = (ProjectStepInfo)DataBinder.GetDataItem(e.Item);      // View Item     var litTsCreated = (Literal)e.Item.FindControl('litTsCreated');     var litTsUpdated = (Literal)e.Item.FindControl('litTsUpdated');     var imgStatus = (Image) e.Item.FindControl('imgStatus');      if (litTsCreated != null) litTsCreated.Text = String.Format('{0:d}', info.TsCreated);     if (litTsUpdated != null) litTsUpdated.Text = String.Format('{0:d}', info.TsCreated);     if (imgStatus != null) imgStatus.ImageUrl = String.Format('/images/icon/project-status/{0}.png', info.StepStatus_StatusId);      // Edit Item     var lvEditProjectSteps_rblStatus = (RadioButtonList) e.Item.FindControl('lvEditProjectSteps_rblStatus');     if (lvEditProjectSteps_rblStatus != null) lvEditProjectSteps_rblStatus.SelectedValue = info.StepStatus_StatusId.ToString();   } } protected void lvEditProjectSteps_OnItemUpdating(object sender, ListViewUpdateEventArgs e) {   if (IsValid)   {     var oController = new Controller();     var lvEditProjectSteps_hdnStepStatusId = (HiddenField) lvEditProjectSteps.EditItem.FindControl('lvEditProjectSteps_hdnStepStatusId');     var lvEditProjectSteps_hdnStepStatusStepId = (HiddenField) lvEditProjectSteps.EditItem.FindControl('lvEditProjectSteps_hdnStepStatusStepId');     var lvEditProjectSteps_rblStatus = (RadioButtonList) lvEditProjectSteps.EditItem.FindControl('lvEditProjectSteps_rblStatus');     var infoStepStatus = oController.StepStatus_SelectOne_StepId_StatusId(Convert.ToInt32(lvEditProjectSteps_hdnStepStatusStepId.Value), Convert.ToInt32(lvEditProjectSteps_rblStatus.SelectedValue));     if (lvEditProjectSteps_hdnStepStatusId != null)     {       e.NewValues['ProjectId'] = Convert.ToInt32(lvEditProjectSteps_hdnProjectId.Value);       e.NewValues['StepStatusId'] = infoStepStatus.Id;     }     else     {       Response.Write('cancel');       e.Cancel = true;     }   }   else   {     Response.Write('cancel, not valid');     e.Cancel = true;   } } protected void lvEditProjectSteps_rblStatus_OnSelectedIndexChanged(object sender, EventArgs e) {   var oController = new Controller();   var rbl = (RadioButtonList)sender;   var lvEditProjectSteps_txtText = (TextBox) rbl.NamingContainer.FindControl('lvEditProjectSteps_txtText');   var lvEditProjectSteps_txtComment = (TextBox)rbl.NamingContainer.FindControl('lvEditProjectSteps_txtComment');   var lvEditProjectSteps_hdnStepStatusStepId = (HiddenField) rbl.NamingContainer.FindControl('lvEditProjectSteps_hdnStepStatusStepId');   if (!String.IsNullOrEmpty(lvEditProjectSteps_hdnStepStatusStepId.Value) && lvEditProjectSteps_txtText != null && lvEditProjectSteps_txtComment != null)   {     var infoStep = oController.Step_SelectOne(Convert.ToInt32(lvEditProjectSteps_hdnStepStatusStepId.Value));     var infoStepStatus = oController.StepStatus_SelectOne_StepId_StatusId(Convert.ToInt32(lvEditProjectSteps_hdnStepStatusStepId.Value), Convert.ToInt32(rbl.SelectedValue));      lvEditProjectSteps_txtText.Text = infoStep.Name;     lvEditProjectSteps_txtComment.Text = infoStepStatus.Text;   } } 

Answer 1

I solved my own problem. There seems to be a bug when selecting a the edit ListViewItem like this (using the example above):

lvEditProjectSteps.EditItem 

but not when you use this method:

lvEditProjectSteps.Items[lvEditProjectSteps.EditIndex] 

hope this helps someone else.