dropdownlist databind!! please help..

[son]

hi all

i have been on this problem for like 3 days now its time for some help cause it driving me insane..

 

i am using SQL SERVER 2000 where my database is stored.. i am using the northwind database.

 

i am using vb.net and asp.net. i have a webform1 that has the connection to the database on the startup page i am using the server explorer to add the sqlconnection , sqladapater and the dataset components.. i am caching the the components if the page is not posted back to the server and filling the dataset with the data: my code on the first form is as follows

 

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
       'Put user code to initialize the page here
       If Not IsPostBack Then
           'add the tables to the cache
                       addtocache("SqlDataAdapter2", SqlDataAdapter2) '"adaptCustomerCustomerDemo"
           

           'fill the datasets
           SqlDataAdapter2.Fill(DsCustomerCustomerDemo1)
           addtocache("DsCustomerCustomerDemo1", DsCustomerCustomerDemo1) 'dsCustomerCustomerDemo
            End If

   End Sub


Sub addtocache(ByVal name As String, ByVal obj As Object)
       If Not IsNothing(Cache(name)) Then Return
       Cache.Add(name, obj, Nothing, DateTime.MaxValue, System.TimeSpan.FromMinutes(20), _
Caching.CacheItemPriority.Default, Nothing)
   End Sub

on the main page(webform1) i have a link which takes you to another webform2 and i have a dropdownlist on webform2 which needs to be databinded to fill up the dropdownlist which i have..my code on webform2 is as follows

 

imports system.data.sqlclient

public sqlDataAdapter2 as sqlDataAdapter  ' 
Public dsCustomerCustomerDemo1 As dsCustomerCustomerDemo

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
       'Put user code to initialize the page here

       
       dsCustomerCustomerDemo1 = Cache("dsCustomerCustomerDemo1")

       If Not IsPostBack Then
      
           drpCustomerCustomerDemo.DataBind()

       End If

   End Sub

 

can someone please help because nothing is filling up my dropdownlist..

thanks in advance... hope i explained myself ok...

[Cassio]

Where are you setting the datasource of your dropdownlist?

[son]

hi thanks for your reply:

 

the datasource i am setting in the webform2 by selecting the dropdownlist and in the properties window of the dropdownlist,

the datasource property to DsCustomerCustomerDemo (name of the dataset), datatextfield to customername, datavalue field customerid. so the datasource is showing in the html aspx file.

 

Where are you setting the datasource of your dropdownlist?

[son]

hi just a short note to say that i solved my problem..

 

just for anyone to know... my SQLADATADAPTER was giving me problems to basically what i did was selected the SQLDATAADAPTER and went on the SELECT COMMAND property opened the heirarchy and build again the command text property with the build in tool...

 

saved my work and it worked fine...

[son]

hi .. another problem cropped up help..

i have got this piece of code below and its not entering in the for ... next loop for me... i cant understand why?

 

Public adaptOrders As SqlDataAdapter
Public dsorders As dsorders
Public dscustomers As dscustomers

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
       'Put user code to initialize the page here
      

       'get the cached variables
       adaptOrders = Cache("adptorders")
       dsorders = Cache("dsorders")
       dscustomers = Cache("dscustomers")

       'run the first time the page is loaded
       If Not IsPostBack Then


           'for each row in the table
           Dim dscustomers As New dsCustomers
           Dim rownext As dsCustomers.CustomersRow
           For Each rownext In dscustomers.Customers
               Dim lstNew As New ListItem
               lstNew.Text = rownext.CustomerID
               lstNew.Value = rownext.CustomerID
               ' add the list item to the drop-down list
               drpCustomer.Items.Add(lstNew)
           Next
           'select the first item in the list
           drpCustomer.SelectedIndex = 0


       End If
   End Sub

 

what i am trying to do is bind the drpcustomer dropdownlist with the cached dataset that i have on webform1, which also has the connection to the database (i am using sql server 2000) and also the data

Adapter is on this page.. the drpcustomer dropdownlist is on webform3... would appreciate it if someone can help.. thanks in advance sonia...

[son]

solved t problem

 

ah ah ah!!! this was really frustrating i solved t problem but with a lot of playing around....

 

for whoever is interested... this is what i had to declare also with the code which i had posted above..

 

Public adaptOrders As SqlDataAdapter
Public orders As dsorders
Public  dscustomers As New dscustomers ' i kept on getting an error here reference to object not set - so just add NEW

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
       'Put user code to initialize the page here
      

       'get the cached variables
       adaptOrders = Cache("adptorders")
       dsorders = Cache("dsorders")
       dscustomers = Cache("dscustomers")

       'run the first time the page is loaded
       If Not IsPostBack Then


           'for each row in the table
           Dim dscustomers As New dsCustomers
dscustomers = Cache("dscustomers") ' i also had to add the cache of my dataset here cause i was also getting instance of object not set

           Dim rownext As dsCustomers.CustomersRow
           For Each rownext In dscustomers.Customers
               Dim lstNew As New ListItem
               lstNew.Text = rownext.CustomerID
               lstNew.Value = rownext.CustomerID
               ' add the list item to the drop-down list
               drpCustomer.Items.Add(lstNew)
           Next
           'select the first item in the list
           drpCustomer.SelectedIndex = 0


       End If
   End Sub

 

works fine..

 

what i would like to know is why did i have to always and and new instance of the object if its declared in the top of class as PUBLIC... if someone could reply back to me would appreciate... i am not satisfied only that it worked.. i would love to know the explanation of it cause i spent a lot of time figuring it out and it was very very frustrating...

 

thanks in advance... :)

[PlausiblyDamp]

You are declaring the dsCustomers twice - once at the page level and once within the postback check, if the dataset is required in multiple routines in the page then declaring at the page level is okay, if this is the only routine that uses it then there is no need to declare it outside the page_load

 

You may want to consider checking if the cache object returns null - as your code makes no checks (hence the reason you were getting the original errors)

 

Also you do not appear to be either filling the dataset anywhere in that code sample or storing the dataset into the Cache object - are there other routines used in this page?