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f.getItem(this) is undefined

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ListBox

This is a migrated thread and some comments may be shown as answers.

Steve Marks asked on 22 Jul 2009, 01:26 AM

Hello,

I have two RadListBox controls. One holds selected items, the other holds the source list of items. Users can select items by transferring them from the source to selected RadListBox. The source list box can be filtered on the fly and I have implemented a web service that gets a new source list. The following JavaScript function is called upon successful completion of the web service call. The data parameter is of type RadComboBoxData which holds the needed return data nicely. There is no equivalent RadListBoxData that I could find.

The issue I'm having is sometimes this function gets an error "f.getItem(this) is undefined". This does not happen that often but often enough. I'm still trying to figure out how to reliably reproduce the error. What I can say for sure is that sometimes when the below function is called to refresh the source list box this error happens and then nothing can be transferred between the two RadListBox controls.

    function fillMultiSelect(data) {
        var listBoxSelected = $find('<listBoxSelected ID>');
        var itemsSelected = listBoxSelected.get_items();

        var listBox = $find('<listBoxSource ID>');
        var itemsSource = listBox.get_items();
        itemsSource.clear();

        for (var i = 0; i < data.NumberOfItems; i++) {
            if (!data.Items[i]) break;
            var item = new Telerik.Web.UI.RadListBoxItem();
            item.set_text(data.Items[i].Text);
            item.set_value(data.Items[i].Value);

            var found = false; // don't add items already selected
            itemsSelected.forEach(function(itemS) { if (itemS.get_text() == item.get_text()) found = true; });
            if (!found) itemsSource.add(item);

        }
    }

Your help would be appreciated.

16 Answers, 1 is accepted

Accepted

answered on 27 Jul 2009, 12:10 PM

Hello,

I have a very similar scenario, in which a RadListBox item that is created in client code and added to the item collection. Before doing this, I need to check whether an item with the same value (or text) already exists in the collection. I've tried a few alternatives to search the collection using the private methods of the listbox object, but none worked for me.

Finally, I've tried your solution, but still with no luck: while using listbox._findItemByText(text) - I've received the error "'undefined' is null or not an object". Both the listbox and the text variables are defined and are seen by the debugger, the error occurs in Telerik code:

_getAllItemsRecursive:function(d,a){var b=a._getChildren();
for(var e=0;e<b.get_count();e++){
var c=b.getItem(e);
Array.add(d,c);
this._getAllItemsRecursive(d,c)
}}

The error occurs while calling the b.get_count() - b is undefined.

Hoewever, this does not occur everytime. Do you have any other solution or workaround to this problem?

Thank you,
Adrian

answered on 27 Jul 2009, 02:27 PM

Hello Albert,

More details about the scenario:

- the code is used in a web user control, on the page multiple instances are present
- in the left part, a listbox is present, in the right part a treeview
- when clicking on a treenode, the node is hidden and if the listbox doesn't contain another item with the same text as the treenode, a new item is created. It's done by calling the client function below.

The code:

dualTreeSelector.prototype.MoveNodeToList =function(node)
    {

                var listbox = $find(this.listBox); //this.listBox is the id of the listbox
                var treeview = $find(this.treeView); //this.treeView is the id of the tree

                 //construct a new list item
                var item = new Telerik.Web.UI.RadListBoxItem();
                item.set_text(node.get_text());
                item.set_value(node.get_value());

            if (listbox._findItemByText(node.get_text()) ==null) //this is where it fails
             {
                //add the new list item
                listbox.trackChanges();
                listbox.get_items().add(item);
                listbox.commitChanges();
             }

                //hide the tree node
                 node.set_visible(false);
    }

answered on 27 Jul 2009, 02:59 PM

Here's a short version, it behaves in the same way:

<%@ Page Language="vb" AutoEventWireup="false" CodeBehind="Test2.aspx.vb" Inherits=".Test2" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
</head>
<body>
    <form id="form1" runat="server">
    <script type="text/javascript">
     function MoveNodeToList(node)
    {

                var listbox = $find('RadListBox1');
                var treeview = $find('RadTreeView1');

                 //construct a new list item
                var item = new Telerik.Web.UI.RadListBoxItem();
                item.set_text(node.get_text());
                item.set_value(node.get_value());

            debugger;
            if (listbox._findItemByText(node.get_text()) ==null) //this is where it fails
             {
                //add the new list item
                listbox.trackChanges();
                listbox.get_items().add(item);
                listbox.commitChanges();
             }

                //hide the tree node
                 node.set_visible(false);
    }

    </script>
    <div>
    <asp:ScriptManager runat="server" id="scriptManager1"></asp:ScriptManager>
        <radC:RadListBox ID="RadListBox1" runat="server">
        <Items>
        <radC:RadListBoxItem Text="Existing item" Value="0" />
        </Items>
        </radC:RadListBox>
        <radC:RadTreeView ID="RadTreeView1" runat="server" OnClientNodeClicked="function(sender,eventArgs){MoveNodeToList(eventArgs.get_node());}">
        <Nodes>
        <radC:RadTreeNode Text="Existing item" Value="0"></radC:RadTreeNode>
        <radC:RadTreeNode Text="Another item" Value="1"></radC:RadTreeNode>
        </Nodes>
        </radC:RadTreeView>
    </div>
    </form>
</body>
</html>

answered on 28 Jul 2009, 01:41 PM

Hi Adrian Petcu,

We have added the fore mentioned methods to the RadListBox. You can test them with the latest internal build. If you want to try them immediately place the following code right after the ScriptManager declaration:

    
            <script type="text/javascript"> 
        
                    Telerik.Web.UI.RadListBox.prototype.findItemByText = function(theText) { 
        
                        var items = this.get_items(); 
        
                        var itemsCount = items.get_count(); 
        
                        for (var i = 0; i < itemsCount; i++) { 
        
                            if (items.getItem(i).get_text() == theText) { 
        
                                return items.getItem(i); 
        
                            } 
        
                        } 
        
                        return null; 
        
                    } 
        
                    Telerik.Web.UI.RadListBox.prototype.findItemByValue = function(theValue) { 
        
                        if (!theValue) return null; 
        
                        var items = this.get_items(); 
        
                        var itemsCount = items.get_count(); 
        
                        for (var i = 0; i < itemsCount; i++) { 
        
                            if (items.getItem(i).get_value() == theValue) { 
        
                                return items.getItem(i); 
        
                            } 
        
                        } 
        
                        return null; 
        
                    } 
        
            </script>

Then you can use the methods like this:

    
            <script type="text/javascript"> 
        
                    function pageLoad() { 
        
                        var listBox = $find("RadListBox1"); 
        
                        var item = listBox.findItemByText("RadListBoxItem7"); 
        
                    } 
        
            </script>

Sincerely yours,
Genady Sergeev
the Telerik team

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answered on 02 Nov 2009, 08:34 PM

I am using the very latest build; just downloaded and installed/update this morning.

Like others I am trying to access the attributes from javascript. I am successfully adding the attr via ItemDataBound..

Protected Sub RadListBox3_ItemDataBound(ByVal sender As Object, ByVal e As Telerik.Web.UI.RadListBoxItemEventArgs) Handles RadListBox3.ItemDataBound

Dim dataSourceRow As DataRowView = DirectCast(e.Item.DataItem, DataRowView)

e.Item.Attributes(

"UsergroupID") = dataSourceRow("UsergroupID").ToString()

End Sub

I have testing and confirmed the attribute is serialized in HTML runtime.

The javascript is halting with the execution of the findItemByAttribute() method.

var

item = listbox3.findItemByAttribute("UsergroupID", 1);

The processdies on line 1257 of the Telerik axd file, at the line..

_getAllItemsRecursive:function(d,a){var b=a._getChildren();

for

(var e=0;

e<b.get_count();

e++){

var c=b.getItem(e);

Array.add(d,c);

this

._getAllItemsRecursive(d,c)

}}

b is null.

answered on 03 Nov 2009, 07:59 AM

Hi David,

I tried your code and I am also unable to search the item using attribute value which is set through ItemDataBound event. As a workaround I tried following code to get the corresponding item without using findItemByAttribute() method.

JavaScript:

    
            <script type="text/javascript"> 
        
                function SerchGetAttribute() { 
        
                    var listBox = $find('<%= RadListBox1.ClientID %>'); 
        
                    var item; 
        
                    for (var i = 0; i < listBox.get_items().get_count(); i++) { 
        
                        if (listBox.get_items().getItem(i).get_attributes().getAttribute("UsergroupID") == "1") { 
        
                            item = listBox.get_items().getItem(i); 
        
                        } 
        
                    } 
        
                    alert(item.get_text()); 
        
                } 
        
            </script>

-Shinu.

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f.getItem(this) is undefined

16 Answers, 1 is accepted