[RESOLVED] ListBox Selected Values to String()

**Hybird** · Sep 24th, 2010, 02:04 PM

Hello all,

I am developing a Webpage that gives the user selection criterial before running a report. There is a asp.net ListBox that I need to get the selected values from. It is obviously a multi select listbox.

I need to pass the selected values as a comma separated string to a parameter used in an SQL query of the ObjectDataSource for the report. I was hoping some how to get the selected items, and load their value into a string array and then use the join( stringArray , "," ) to get the selected values into a string to send as a parameter to my objectdatasource but I cant seem to figure this out..

Ideally if code worked my way I would want to do something like this:

Declare StringArray

for each selected item in Mylistbox
Add selected value to StringArray

Set parameter = join( StringArray , "," )

Obviously this is what I need syntax for.. I pretty much just need to know how to get a string array or all selected values. Any ideas?

**Shaggy Hiker** · Sep 24th, 2010, 02:08 PM

I haven't used ASP, but in the Windows Listbox there is a SelectedItems list, which is alreayd a collection. I would expect that you can use .ToArray on that to turn it into a string array. However, this won't necessarily work unless your listbox is just displaying a list of strings. If you have it bound to a datatable, then the return from SelectedItems may not be useable in that fashion. In that case, you could use LINQ to get the values if you are working in .NET 3.5 or higher.

Since I am off into the speculative weeds at this point, I won't go further at this time. Try the SelectedItems.ToArray to see if that gets you what you need, and if not, then state what version of the framework you are targeting.

**Pradeep1210** · Sep 24th, 2010, 02:32 PM

Are you using asp.net?

Try this:
(not tested but should work in both asp as well as asp.net)

vb Code:

Dim selectedItems as String = Request(MyListBox)
 
'selectedItems should now have a comma separated list of selected items.
'lets test
Response.Write(selectedItems)

**Hybird** · Sep 24th, 2010, 02:57 PM

I am using Visual Web Developer 2008. It uses version 3.5 of the .NET framework.

I really like Pradeep1210's solution but I can't get it to work. I get the following error:

Value of type 'System.Web.UI.WebControls.ListBox' cannot be converted to 'String'

It underlines the ChooseNDR object name.

I don't know much about ASP.Net or Vb.net or anything. I just have a code behind file for my webform. It has Ajax.controls associated to it if thats what your asking? If it helps, this is the code behind for my webform:

Code:

<%@ Page Language="VB" %>

<%@ Register assembly="Microsoft.ReportViewer.WebForms, Version=9.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" namespace="Microsoft.Reporting.WebForms" tagprefix="rsweb" %>

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

<script runat="server">

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
            
        'This is where I am writing my code in VB
        Dim selectedItems As String = Request(ChooseNDR)

        Label1.Text = selectedItems
        
        Dim RDS As New ReportDataSource
        RDS.DataSourceId = "ObjectDataSource1"
        RDS.Name = "Database_JobGroups"
        ReportViewer1.LocalReport.DataSources.Clear()
        ReportViewer1.LocalReport.DataSources.Add(RDS)
        ReportViewer1.LocalReport.Refresh()
        ReportViewer1.Visible = True

End Sub

</script>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <style type="text/css">
        .style1
        {
            height: 335px;
        }
    </style>
</head>
<body>
    <form id="form1" runat="server">
    <div class="style1">
    
        <span lang="en-ca">Choose NDR list:<br />
        </span>
                    <asp:ListBox ID="ChooseNDR" runat="server" SelectionMode="Multiple" 
                        Width="312px" Height="121px" DataSourceID="NDRCodeDS" DataTextField="JobCode" 
                        DataValueField="JobCodeID" AppendDataBoundItems="True">
                        <asp:ListItem Value="-1">All</asp:ListItem>
                    </asp:ListBox>
                <br />
        <br />
        <span lang="en-ca">Hit this to display report:</span><br />
        <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" 
            Width="155px" />
    
        <br />
        <br />
        <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
    
    </div>
    <rsweb:ReportViewer ID="ReportViewer1" runat="server" Font-Names="Verdana" 
        Font-Size="8pt" Height="400px" Width="100%">
        <LocalReport ReportPath="ztest.rdlc">
        </LocalReport>
    </rsweb:ReportViewer>
    <asp:ObjectDataSource ID="NDRCodeDS" runat="server" 
        OldValuesParameterFormatString="original_{0}" 
        SelectMethod="GetJobGroupsDataByActive" 
        TypeName="DatabaseTableAdapters.JobGroupsTableAdapter">
    </asp:ObjectDataSource>
    <asp:ObjectDataSource ID="ObjectDataSource1" runat="server" 
        OldValuesParameterFormatString="original_{0}" 
        SelectMethod="GetJobGroupDataByJobCodeID" TypeName="JobGroupBLL">
        <SelectParameters>
            <asp:ControlParameter ControlID="ChooseNDR" Name="JobCodeID" 
                PropertyName="SelectedValue" Type="Int32" />
        </SelectParameters>
    </asp:ObjectDataSource>
    </form>
</body>
</html>

**Hybird** · Sep 24th, 2010, 03:10 PM

I got it working with the following code, but would really like to simplify it down to how you have described with this Request() thinger. Also yes I am using ASP.NET cause the page ends with .aspx

vb Code:

Label1.Text = ""
        Dim selectionList As New System.Collections.Generic.List(Of String)
        
 
        For Each itm As ListItem In ChooseNDR.Items
            If itm.Selected = True Then
                selectionList.Add(itm.Value)
            End If
        Next
        
        Label1.Text = String.Join(",", selectionList.ToArray)

**Hybird** · Sep 24th, 2010, 03:12 PM

I dont know why my other post didn't go through but I am developing with the following:

-Visual Web Developer 2008
-.Net frame work 3.5
-Designing a Web Form with AJAX controls and VB code behind

**Pradeep1210** · Sep 24th, 2010, 03:20 PM

What happens if you replace that code with this one line:

Code:

Label1.Text = Request("ChooseNDR")

**si_the_geek** · Sep 24th, 2010, 03:25 PM

Thread moved from the 'VB.Net' forum to the 'ASP.Net' forum

Originally Posted by Hybird

I dont know why my other post didn't go through

Part of our anti-spam system puts some posts from newer members in a queue to be manually approved, and I have now approved it so it is shown above.

**Hybird** · Sep 24th, 2010, 03:26 PM

Wow... simply wow. Thank you so much, you have no idea how easy that has made things for me!

**Hybird** · Sep 24th, 2010, 03:40 PM

Quick editition, is there a way to get all the values into a comma separated list even if they are not selected? I want to do something along the lines of this:

vb Code:

If ChooseNDR.SelectedItem.Value = -1 Then
            Label1.Text = Request("ChooseNDR")
        Else
            Label1.Text = String.Join(",", ChooseNDR.SelectedValue.ToArray)
        End If
 
 
End If

Obviously again my sytax is wrong on the Join() part, but is there something that can be done to do this? I have a appended item called ALL where it should pull all values from the list.

**Pradeep1210** · Sep 24th, 2010, 04:12 PM

NO, for that you will have to loop thru the list items.
But consider this: The source from where you filled that list must already have all the items in the first place. So cant you use the same source?

**Pradeep1210** · Sep 24th, 2010, 04:20 PM

From what you indicated in your earlier posts, you are using .net 3.5
So you can use LINQ to simplify things.

(again not tested code, but should work)

vb.net Code:

Dim allListItems = From li in ChooseNDR.Items Select li.value
Label1.Text = Join(allListItems.ToArray, ",")

**gep13** · Sep 25th, 2010, 03:59 AM

Just a thought...

Where are you populating the ListBox? Does this happen in the ASPX markup, or are you DataBinding the ListBox somewhere else. I only ask because, if this is a fixed ListBox, you already know this information ahead of time, so you might not have to loop through all the items contained within it. Or, if you are DataBinding, you could create the string at the time of DataBinding.

Gary

**Hybird** · Sep 27th, 2010, 11:18 AM

Thanks, I will take a look at that LINQ stuff. As for how the data is getting populated... This project involves creating a frontpage for a rather complex database. So when I am populating the listbox I am databinding it to an objectdatasource that is connected to the database, so I am doing this in ASP.net I would guess. I then add an option of 'All' in the VB markup as an appended item to the list. So no, I do not have an all option in the dataset. And this list box is cascaded off of another selection, so the values can change as we select different stuff.

I am building a front page for a report, and I send back a comma separated string to a table valued function which generates a table of all the values in the string. I then Join to that table in my query to get the possible selections. In order for the all option to work, I have to send all the possible selections to that function.

Before I was doing some boolean algebra in the WHERE clause of my query such as :

WHERE (cityID = @cityID OR @cityID = -1)

because -1 is never an id of that field, and hence it would return all. But I have read this is bad for performance of stored procs, and also the client wants to be able to send multiple values. So thats a bit of an overview.

**Hybird** · Sep 27th, 2010, 11:43 AM

Originally Posted by Pradeep1210

From what you indicated in your earlier posts, you are using .net 3.5
So you can use LINQ to simplify things.

(again not tested code, but should work)

vb.net Code:

Dim allListItems = From li in ChooseNDR.Items Select li.value
Label1.Text = Join(allListItems.ToArray, ",")

Thank you again, this does work fine. Just to clarify, this is what I ended up with.

vb.net Code:

'This is done on the 'On_click' event of a button. Printing the values to 
'a label is done solely for testing purposes. Really I'd send them to a parameter
        Dim allListItems = From li In ChooseNDR.Items Select li.value
        Label1.Text = ""
        
        If ChooseNDR.SelectedItem.Value = -1 Then
            Label1.Text = Join(allListItems.ToArray, ",")
        Else
            Label1.Text = Request("ChooseNDR")
        End If

**gep13** · Sep 27th, 2010, 02:47 PM

Sounds like you have got a working solution

Can you remember to mark your thread as resolved?

Thanks

Gary

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