page not picking up listbox items
Hi all,
hopefully this is easy.
I have two listboxes on my pages, one of which is populated with a list of types from a database. The second listbox next to it contains will contain all those associated with the product i am entering.
using javascript i move the items between the tables. this is all working.
now when i click the add button (this will iterate through the added types in the second list box and add the associations to the database). it is saying the number of items in the list is 0? can anyone explain why please?
i though it may be something to do with the postback but his is protected.
Code:
<%@ Page Language="vb" AutoEventWireup="true" CodeFile="add_product.aspx.vb" Theme="Admin" Inherits="add_product" debug="true"%>
<!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 id="Head1" runat="server">
<title>Add a New Product</title>
...
<tr>
<td>
<asp:listbox CssClass="stdListBox" id="availableTypes" runat="server"/>
<asp:listbox CssClass="stdListBox" id="productTypes" runat="server"/>
</td>
</tr>
...
<tr>
<td align="center" colspan=2><asp:button id="nextPage" text="Next >>" OnCommand="AddProductClick" runat="server"/> </td>
</tr>
Code:
Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
'*************** AUTH STUFF *************************************
Dim MM_authFailedURL As String = "..\admin_access_denied.aspx"
Dim MM_grantAccess As Boolean = false
If Session("MM_Username") <> "" Then
MM_grantAccess = true
End If
If Not MM_grantAccess Then
Response.Redirect(MM_authFailedURL)
End If
'*****************************************************************
If Not Page.IsPostBack Then
Dim dt As DataTable
oQry = "SELECT supplierID, name FROM suppliers ORDER BY name"
SupplierDropDown.DataSource = CreateDataSource(oQry)
SupplierDropDown.DataTextField = "name"
SupplierDropDown.DataValueField = "supplierID"
SupplierDropDown.DataBind()
'initialize the image datagrid
dt = new DataTable("ProductImages")
dt.Columns.Add(new DataColumn("imageID", GetType(Integer)))
dt.Columns.Add(new DataColumn("image", GetType(String)))
dt.NewRow()
If Not (Request.QueryString("ID")Is Nothing) Then
productID = Request.QueryString("ID")
'set supplier
SupplierDropDown.SelectedItem.Value = productID
'now do lookup for rest of information
oQry = "SELECT * FROM products WHERE productID=" + productID
Dim pDataSet As DataSet = CreateDataSource(oQry)
productName.Text = pDataSet.Tables(0).Rows(0).Item("name")
briefDescription.Text = pDataSet.Tables(0).Rows(0).Item("brief_des")
detailedDescription.Text = pDataSet.Tables(0).Rows(0).Item("full_des")
labelInfo.Text = pDataSet.Tables(0).Rows(0).Item("label")
directions.Text = pDataSet.Tables(0).Rows(0).Item("directions")
'now select all sizes not associated
oQry = "SELECT * FROM sizes WHERE sizeID NOT IN (SELECT sizeID from productSize WHERE productID=" + productID + ") ORDER BY sizes.size"
pDataSet = CreateDataSource(oQry)
availableSizes.DataSource = pDataSet
availableSizes.DataTextField = "size"
availableSizes.DataValueField = "sizeID"
availableSizes.DataBind()
'and select all those which are associated
oQry = "SELECT * FROM sizes,productSize WHERE sizes.sizeID = productSize.sizeID AND productSize.productID=" + productID + " ORDER BY size"
pDataSet = CreateDataSource(oQry)
productSizes.DataSource = pDataSet
productSizes.DataTextField = "size"
productSizes.DataValueField = "sizeID"
productSizes.DataBind()
'do the same for all the types
oQry = "SELECT * FROM types WHERE typeID NOT IN (SELECT typeID from productType WHERE productID=" & productID & ") ORDER BY types.type"
pDataSet = CreateDataSource(oQry)
availableTypes.DataSource = pDataSet
availableTypes.DataTextField = "type"
availableTypes.DataValueField = "typeID"
availableTypes.DataBind()
oQry = "SELECT * FROM types,productType WHERE types.typeID = productType.typeID AND productType.productID=" & productID & " ORDER BY type"
pDataSet = CreateDataSource(oQry)
productTypes.DataSource = pDataSet
productTypes.DataTextField = "type"
productTypes.DataValueField = "typeID"
productTypes.DataBind()
'now check for images
oQry = "SELECT * FROM ((images INNER JOIN productImages ON images.imageID = productImages.imageID) INNER JOIN products ON products.productID = productImages.productID) WHERE products.productID=" + productID
'response.write(oQry)
pDataSet = CreateDataSource(oQry)
Dim i As Integer = 0
For i = 0 To pDataSet.Tables(0).Rows.Count-1
Dim newImageRow As DataRow = dt.NewRow()
newImageRow("imageID") = pDataSet.Tables(0).Rows(i).Item("imageID")
newImageRow("image") = pDataSet.Tables(0).rows(i).Item("location")
Next
Else
'select all sizes
oQry = "SELECT * FROM sizes ORDER BY size"
Dim pDataSet As DataSet = CreateDataSource(oQry)
availableSizes.DataSource = pDataSet
availableSizes.DataTextField = "size"
availableSizes.DataValueField = "sizeID"
availableSizes.DataBind()
'select all types
oQry = "SELECT * FROM types ORDER BY type"
pDataSet = CreateDataSource(oQry)
availableTypes.DataSource = pDataSet
availableTypes.DataTextField = "type"
availableTypes.DataValueField = "typeID"
availableTypes.DataBind()
End If
'now databind datagrid
imageDatagrid.DataSource = dt
imageDatagrid.DataBind()
Session("imagesDataTable")=dt
End If
Response.Write("always getting to here?? <br>")
End Sub
Re: page not picking up listbox items
I didn't read your code, but it probably has to do with viewstate. Javascript doesn't add the items to the viewstate, so when you post back, the control still thinks it's empty.
There's probably a better way to get around it, but what I've done in the past is build a comma delimited string in a hidden textbox (using javascript) before I postback, then split it in the server-side code.
Re: page not picking up listbox items
Hi Mike,
thanks for the reply, i see.
so what you are saying is i would have a hidden label and on the onclick javascript add method append to the string and on the remove remove from the string?
would this not have the same problem as before with it not being seeing the labels string?
(sorry a newb as you can tell!)
Re: page not picking up listbox items
Make it a hidden textbox, not a label. This is not an asp:TextBox Visible=false - this is an asp:TextBox with a style="visibility:hidden;".
Textboxes and Listboxes deal with viewstate differently, so you will get the value of the textbox on postback.
I'd build the comma delimited list in the javascript onSubmit handler, rather than adding and removing and dealing with the complication that entails.
