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[Solved] Specified cast is not valid on checkbox in ajax grid

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Grid

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Mattias asked on 21 Nov 2009, 05:09 PM

Hi,
I'm getting "Specified cast is not valid" when clicking "Add new".
When clicking on "Edit" on an existing row works fine.

    
            <telerik:GridTemplateColumn UniqueName="CheckListChecked" HeaderText="<%$ Resources:resources,Label_Finished %>"> 
        
            <ItemTemplate> 
        
                  <asp:CheckBox ID="checkBoxCheckListChecked" Enabled="false" runat="server" Checked='<%# (Container is GridEditFormInsertItem) ? false : Eval("IsChecked") %>' /> 
        
            </ItemTemplate> 
        
            <EditItemTemplate> 
        
                  <asp:CheckBox ID="checkBoxCheckListChecked" runat="server" Checked='<%# (Container is GridEditFormInsertItem) ? false : Eval("IsChecked") %>' /> 
        
            </EditItemTemplate> 
        
            </telerik:GridTemplateColumn>

The checkbox in itemtemplate works but not the one in edititemtemplate when creating a new row. Why?

/Mattias

3 Answers, 1 is accepted

answered on 23 Nov 2009, 05:41 AM

Hello Mattias,

This error is found to occur when your grid instance cannot bind a value for the newly inserted item through the Eval()/Bind() syntax you have hard-coded. To avoid this error you can preset the value of the checkbox when binding to a grid item on the InitInsertCommand as shown below:
c#:

    
            protected void RadGrid1_ItemCommand(object source, Telerik.Web.UI.GridCommandEventArgs e) 
        
                 { 
        
                if ((e.CommandName == RadGrid.InitInsertCommandName))  
        
                       { 
        
                    e.Canceled = true; 
        
                    //Prepare an IDictionary with the predefined values 
        
                    System.Collections.Specialized.ListDictionary newValues = new System.Collections.Specialized.ListDictionary();       
        
                    //set initial checked state for the checkbox on init insert 
        
                    newValues("IsChecked") = false; 
        
                    //Insert the item and rebind 
        
                    e.Item.OwnerTableView.InsertItem(newValues); 
        
                } 
        
            }

For reference, check out the following link:
Known reasons for error messages

Hope this helps...
Princy.

answered on 23 Nov 2009, 08:01 AM

Thank you Princy.
It works! But it feels like a walk around, it would be great if the grid could check this itself in future release.
And it seems its only checkboxes that's not working (as far as I tested), cause I have this in the code as well and it doesn't complain about it.

    
            <telerik:GridTemplateColumn UniqueName="CheckListName" HeaderText="<%$ Resources:resources,Label_Title %>"> 
        
            <ItemTemplate> 
        
                  <asp:Label ID="labelCheckListName" runat="server" Text='<%# Eval("Name") %>'></asp:Label> 
        
            </ItemTemplate> 
        
            <EditItemTemplate> 
        
                  <asp:TextBox ID="textBoxCheckListName" runat="server" Text='<%# Eval("Name") %>'></asp:TextBox> 
        
                <asp:RequiredFieldValidator ID="requiredFieldValidatorHeading" runat="server"  
        
            ErrorMessage="obligatorisk" ControlToValidate="textBoxCheckListName" ValidationGroup="validationGroupCheckList"></asp:RequiredFieldValidator> 
        
            </EditItemTemplate> 
        
            </telerik:GridTemplateColumn>

Regards,
Mattias