Moving items between listboxes in ASP.net/PHP example

Ever wanted to move items between two listboxes in ASP.net (or PHP for that matter)?

Someone wanted the exact same thing on codeproject.com a while ago but I didn't give much thought to it, until someone at work asked me how to do it - since he wasn't able to find a viable solution on the internet.

The solution I scripted wasn't as simple as I thought, nor would have liked it to be, my feeling was that one would be able to alter the two listboxes easily using javascript and simply "harvest" the changes (from the Request variables) when its submitted to the server.

The reality however is that only items selected(or highlighted) in the listboxes, will be returned to the server, not the state of the listboxes - so we need to somehow send the state of the listboxes along with the page request.

What I did was, I wrote a javascript script, that serialized the contents of the listboxes as xml to a hiddenfield on the page - whenever you submit the form to the server, a xml string containing the state of the listboxes get sent along - which one can easily process server side (which I will show you just in a while).

You can download the full working source code here, contains sources for ASP.net(C# & VB.NET) and PHP source code.

 
function move(fromID, toID, containerID)
{
    var from = document.getElementById(fromID);
    var to = document.getElementById(toID);
 
    for (var i = 0; i < from.options.length; i++)
    {
        if (from.options[i].selected)
        {					
            to.options.add(new Option(from.options[i].text,from.options[i].value))
            from.remove(i--);
        }
    }
 
    var container = document.getElementById(containerID);	
    container.value = escape("<listboxes>" + serialize(from) + serialize(to) + "</listboxes>");
}
 
function serialize(dropdown)
{	
    var value = '<' + dropdown.id + '>';	
    for (var i = 0; i < dropdown.options.length; i++)
    {
        value+= '<option><key><![CDATA[' + dropdown.options[i].text + ']]></key><value><![CDATA[' + dropdown.options[i].value + ']]></value></option>';
    }
    value+='</' + dropdown.id + '>';
    return value
}
 
function unselect(listbox)
{
    document.getElementById(listbox).selectedIndex=-1;
}

Tying it all together (javascript with some .net code), you can easily write yourself an usercontrol, like I did in my example, or create a composite control.

The .net code below is pretty straighforward, you'll noticed two publicly exposed ListBox properties (lstFrom, lstTo), giving us easy access to the listboxes.

If you really need to, you can easily add third, forth listboxes (with slight changes to the javascript code)

The PHP code is quite a bit more involved, I had to create a few classes that give similiar control of what you would expect from an ASP.NET server side control. There is a lot easier ways to do this, but I believe this is a fairly manageable approach.

C#

 
using System;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml;
 
public partial class ListPicker : System.Web.UI.UserControl
{
    private XmlDocument _xmlDocument = new XmlDocument();
 
    public ListBox fromListBox
    {
        get
        {
            return lstFrom;
        }
    }
 
    public ListBox toListBox
    {
        get
        {
            return lstTo;
        }
    }
 
    private void PopulateListBox(ListBox listBox)
    {
        listBox.Items.Clear();
        XmlNodeList nodes = _xmlDocument.SelectNodes("listboxes/" + listBox.ClientID + "/option");
        foreach (XmlNode node in nodes)
        {
            listBox.Items.Add(new ListItem(node["key"].InnerText, node["value"].InnerText));
        }
    }
 
    private void PopulateListBoxes()
    {        
        _xmlDocument.LoadXml(HttpUtility.UrlDecode(hdnDropdowns.Value));
        PopulateListBox(lstFrom);
        PopulateListBox(lstTo);
    }
 
    protected void Page_Load(object sender, EventArgs e)
    {
        Page.ClientScript.RegisterClientScriptInclude("listboxjs", Page.TemplateSourceDirectory + "/js/listbox.js");
 
        if (!IsPostBack)
        {
            String movejs = "move('{0}','{1}','{2}')";
            String unselectjs = "unselect('{0}')";
            lstFrom.Attributes["onclick"] = String.Format(unselectjs, lstTo.ClientID);
            lstTo.Attributes["onclick"] = String.Format(unselectjs, lstFrom.ClientID);
            btnTo.Attributes["onclick"] = String.Format(movejs, lstFrom.ClientID, lstTo.ClientID, hdnDropdowns.ClientID);
            btnFrom.Attributes["onclick"] = String.Format(movejs, lstTo.ClientID, lstFrom.ClientID, hdnDropdowns.ClientID);
        }
        else
        {
            if (!(String.IsNullOrEmpty(hdnDropdowns.Value)))
            {
                PopulateListBoxes();
            }
        }
    }
}

VB.net

 
Imports System.Xml
 
Partial Class ListPicker
    Inherits System.Web.UI.UserControl
 
    Private _xmlDocument As New XmlDocument()
 
    Public ReadOnly Property fromListBox() As ListBox
        Get
            Return lstFrom
        End Get
    End Property
 
    Public ReadOnly Property toListBox() As ListBox
        Get
            Return lstTo
        End Get
    End Property
 
    Private Sub PopulateListBox(ByVal lstBox As ListBox)
        lstBox.Items.Clear()
        Dim nodes As XmlNodeList = _xmlDocument.SelectNodes("listboxes/" + lstBox.ClientID + "/option")
        For Each node As XmlNode In nodes
            lstBox.Items.Add(New ListItem(node.Item("key").InnerText, node.Item("value").InnerText))
        Next
    End Sub
 
    Private Sub PopulateListBoxes()
        _xmlDocument.LoadXml(HttpUtility.UrlDecode(hdnDropdowns.Value))
        PopulateListBox(lstFrom)
        PopulateListBox(lstTo)
    End Sub
 
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Page.ClientScript.RegisterClientScriptInclude("listboxjs", Page.TemplateSourceDirectory & "/js/listbox.js")
 
        If Not IsPostBack Then
            Dim movejs As String = "move('{0}','{1}','{2}')"
            Dim unselectjs As String = "unselect('{0}')"
 
            lstFrom.Attributes("onclick") = String.Format(unselectjs, lstTo.ClientID)
            lstTo.Attributes("onclick") = String.Format(unselectjs, lstFrom.ClientID)
            btnTo.Attributes("onclick") = String.Format(movejs, lstFrom.ClientID, lstTo.ClientID, hdnDropdowns.ClientID)
            btnFrom.Attributes("onclick") = String.Format(movejs, lstTo.ClientID, lstFrom.ClientID, hdnDropdowns.ClientID)
        Else
            If Not String.IsNullOrEmpty(hdnDropdowns.Value) Then
                PopulateListBoxes()
            End If
        End If
    End Sub
End Class

PHP

 
<?php
 
require_once("controls.php");
require_once("listbox.php");
 
class listpicker extends controls
{
    var $lstFrom;
    var $lstTo;
    var $deserializable;
 
    function listpicker($id)
    {
        $this->attributes['id'] = $id;
        $this->lstFrom = new listbox($id.'_lstFrom');
        $this->lstFrom->attributes['style'] = 'width:200px';
        $this->lstFrom->attributes['onclick'] = "unselect('".$id."_lstTo')";	
        $this->lstTo = new listbox($id.'_lstTo');
        $this->lstTo->attributes['style'] = 'width:200px';
        $this->lstTo->attributes['onclick'] = "unselect('".$id."_lstFrom')";
 
        if ($_REQUEST[$id.'$hdnDropdowns'])
        {
            $this->deserializable = true;
            $this->xml(urldecode($_REQUEST[$id.'$hdnDropdowns']));			
        }	
    }
 
    function render()
    {	
    $id = $this->attributes['id'];
    $html='<table>
                <tr>
                    <td>'
                        .$this->lstFrom->render().
                    '</td>
                    <td>
                        <input id="btnTo" type="button" value=">>" onclick="move(\''.$id.'_lstFrom\',\''.$id.'_lstTo\',\''.$id.'_hdnDropdowns\')" />
                            <br />
                        <input id="btnFrom" type="button" value="<<" onclick="move(\''.$id.'_lstTo\',\''.$id.'_lstFrom\',\''.$id.'_hdnDropdowns\')" />
                    </td>
                    <td>'		
                        .$this->lstTo->render().
                    '</td>
                </tr>
            </table>
	        <input type="hidden" ID="'.$id.'_hdnDropdowns" name="'.$id.'$hdnDropdowns" />';		
    return $html;
    }
 
    function xml($text) 
    {		
        $id = $this->attributes['id'];
        $parser = xml_parser_create();
        xml_parse_into_struct($parser, $text, $vals);
        xml_parser_free($parser);
        $tag = "";
 
        for($i = 0; $i < count($vals); $i++)
        {	
            switch($vals[$i]['tag'])
            {
                case strtoupper($id.'_lstFrom') : $tag = "lstFrom";	break;
                case strtoupper($id.'_lstTo') : $tag = "lstTo";	break;
            }
 
            if (($tag) && ($vals[$i]['tag'] == "KEY"))
            {
                $this->{$tag}->addItem($vals[$i]['value'], $vals[$i+1]['value']);					
            }
        }
    }
}
 
?>

Posted by - Christoff Truter
Date - 2008-06-12 17:07:43

Comments

move

so very nice coding....easily understand this code

Posted by - Elumalai
Date - 2010-08-24 07:57:33

Hi John Thank you for your contribution. At a stage I am going to write a follow-up post (perhaps article) - or lets call it an evolution post of this one, which will include a number of ways to achieve this in ASP.net. Things like Json, JQuery etc etc, since JQuery seems to be a standard in ASP.net 4.0 - I was quite surprised at the beginning of the year when I installed VS 2010 and saw JQuery included in the project templates.(So I guess JQuery is something devs need to take more seriously) Anyway... thanks again :)

Posted by - Christoff Truter
Date - 2010-08-19 08:29:13

Thanks and here is a mod I made

I don't know if you are still monitoring these posts but thank you for the code to move items between list boxes. I added a function to move them up and down in asp.net which needed your serialization to hidden field for .net to get the view state correct. If anyone is interested here is the code I added (do similar for move down): function moveUp(listID, containerID) { var theList = document.getElementById(listID); for (var i = 1; i < theList.options.length; i++) { if (theList.options[i].selected) { var oldValue = theList.options[i].value; var oldText = theList.options[i].text; theList.options[i].value = theList.options[i-1].value; theList.options[i].text = theList.options[i-1].text; theList.options[i-1].value = oldValue; theList.options[i-1].text = oldText; theList.options[i-1].selected = true; theList.options[i].selected = false; break; } } var container = document.getElementById(containerID); container.value = escape("<listboxes>" + serialize(theList) + "</listboxes>"); }

Posted by - John Lee
Date - 2010-08-19 01:53:42

Re: 10+ Items

The items doesn't actually disappear, when moving an item from one list to another, it appends the moved items to the bottom of the list - hence the scrollbar. If you feel it isn't userfriendly, you can always rather prepend the moved items. e.g. in the listbox.js file at about line 19, change to.options.add(new Option(from.options[i].text,from.options[i].value)) to to.options.add(new Option(from.options[i].text,from.options[i].value), 0) Alternatively you can also resize the height of list (which brings you back to your previous issue)

Posted by - Christoff Truter
Date - 2010-05-08 08:43:37

10+ items?

and I am using php and have actually 150 records to show!

Posted by - Kris
Date - 2010-05-07 21:58:28

10+ items?

When you have abt 20 Records, in short when a horizontal scroll bar appears in the from list -> and you move items from left to right. Try moving items back from right to left. The item dissapears. Is there any solution to that? Please reply back.. It would be helpful!

Posted by - Kris
Date - 2010-05-07 21:56:46

Sorting ASP.Net ListItems

/// <summary> /// Sorts the list items as an integer with five digits - Store Number /// </summary> /// <param name="items">The list items to be sorted</param> private void SortStoreListItem (ListItemCollection items) { SortedList<int, string> sl = new SortedList<int, string>(); foreach (ListItem item in items) { sl.Add(int.Parse(item.Text), item.Value); } items.Clear(); foreach (KeyValuePair<int, string> item in sl) { items.Add(new ListItem(item.Key.ToString("00000"), item.Value)); } } Enjoy! Rob

Posted by - Rob Bratton
Date - 2010-04-22 19:40:20

RE: Iteration

Yes Please! It would make a big difference to have other ways of using your code

Posted by - bri
Date - 2010-02-03 12:16:43

Iteration

Basically you'll need to iterate through your query results, adding items to the listbox via your iteration, do you need an example of how to do this?

Posted by - Christoff Truter
Date - 2010-02-03 11:28:02

HELP

thanks that worked. If you dont mind me asking how would i work a list box into this where the content comes from a database and not your list. So box 1 is "NewTownList" dynamically populated using sql SELECT Query "this works" just need to know how i would tie "NewTownList" into your code Thanks a mil

Posted by - bri
Date - 2010-02-02 14:54:30

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