Having trouble with dynamic controls on my ASP.Net web site - asp.net

Question

I have an asp.net web page which is giving me some problems. I developed the following classes to generate search filters for the page. The search process is not important as it already works. I want to dynamically generate the search filters.
Imports Microsoft.VisualBasic
Imports System.Collections.Generic
Imports System.Collections.ObjectModel
Imports MEI.SPDocuments.Type
Public Class SearchFilter
Private WithEvents _genreDropDown As DropDownList
Private WithEvents _subGenreDropDown As DropDownList
Private WithEvents _txtValue As TextBox
Private _txtBoxAutoCompleteExtender As AjaxControlToolkit.AutoCompleteExtender
Private _filterGenres As Collection(Of String)
Private _programSubGenres() As String = {"Program ID,GetPrograms", "Territory ID,GetTerritories", _
"Rep Name,GetRepNames", "District ID,GetDistricts", "DM Name,GetDMNames", "Region ID,GetRegions", _
"RM Name,GetRMNames", "Speaker Counter,GetSpeaker", "Vedor ID,GetVendors", "Vendor Name,GetVendorName", _
"Date Range,", "City,", "State,", "Pay To,", "Expense Range,", "PIF ID,GetPifs"}
Private _speakerSubGenres() As String = {"Speaker Counter,GetSpeaker", "Speaker Last Name,GetSpeakerLNames", "Speaker First Name,GetSpeakerFNames"}
Private _expenseSubGenres() As String = {"Expense Counter,GetExpenses"}
Private _vendorSubGenres() As String = {"Vendor ID,GetVendors", "Vendor Name,GetVendorName"}
Private _trackSubGenres() As String = {"Track Number,GetTracks", "HCP First Name,GetHCPFName", "HCP Last NameGetHCPLName"}
Public Sub New(ByVal company As CompanyCode, ByVal year As DocumentYearCode)
_filterGenres = New Collection(Of String)
_txtValue = New TextBox
_txtValue.ID = Guid.NewGuid.ToString
_txtBoxAutoCompleteExtender = New AjaxControlToolkit.AutoCompleteExtender
With _txtBoxAutoCompleteExtender
.ID = "AC__" + _txtValue.ID
.MinimumPrefixLength = 1
.EnableCaching = False
.ServicePath = "~/AutoComplete.asmx"
.ServiceMethod = "PlaceHolder"
.TargetControlID = _txtValue.ID
.CompletionListCssClass = "CompletionList"
.CompletionListHighlightedItemCssClass = "ItemHighlighted"
.CompletionListItemCssClass = "ListItem"
.DelimiterCharacters = ""
.Enabled = True
End With
Select Case company
Case CompanyCode.AbbottAnimalHealth, CompanyCode.AbbottDiabetesCare, CompanyCode.AbbottDiagnosticsDivision, CompanyCode.AbbottMedicalOptics, CompanyCode.AbbottMolecular, _
CompanyCode.AbbottPointOfCare, CompanyCode.AbbottVascular, CompanyCode.Corporate, CompanyCode.DivAbbottNutrition, CompanyCode.EstablishedProductsDivision, _
CompanyCode.GlobalPharmaceuticalResearchAndDevelopment, CompanyCode.GlobalStrategicMarketingAndServices, CompanyCode.PharmaseuticalProductsGroup, _
CompanyCode.ProprietaryPharmaceuticalsDivision, CompanyCode.RegulatoryAffairsPPG
_filterGenres.Add("Div Docs")
Case Else
_filterGenres.Add("Program")
_filterGenres.Add("Speaker")
_filterGenres.Add("Expense")
_filterGenres.Add("Vendor")
End Select
_genreDropDown = New DropDownList
_genreDropDown.AutoPostBack = True
_genreDropDown.Attributes.Add("runat", "server")
AddHandler _genreDropDown.SelectedIndexChanged, AddressOf _genreDropDown_ItemChanged
_subGenreDropDown = New DropDownList
_subGenreDropDown.AutoPostBack = True
_subGenreDropDown.Attributes.Add("runat", "server")
AddHandler _subGenreDropDown.SelectedIndexChanged, AddressOf _subGenreDropDown_ItemChanged
PopulateDDls()
End Sub
Private Sub PopulateDDls()
_genreDropDown.Items.Add("")
For Each s As String In _filterGenres
_genreDropDown.Items.Add(s)
Next
End Sub
Private Sub _genreDropDown_ItemChanged(ByVal sender As Object, ByVal e As System.EventArgs)
_subGenreDropDown.Items.Clear()
_subGenreDropDown.Items.Add("")
Select Case _genreDropDown.SelectedItem.ToString
Case "Program"
For Each s As String In _programSubGenres
Dim li As New ListItem(s.Split(CChar(","))(0), s.Split(CChar(","))(1))
_subGenreDropDown.Items.Add(li)
Next
Case "Speaker"
For Each s As String In _speakerSubGenres
Dim li As New ListItem(s.Split(CChar(","))(0), s.Split(CChar(","))(1))
_subGenreDropDown.Items.Add(li)
Next
Case "Expense"
For Each s As String In _expenseSubGenres
Dim li As New ListItem(s.Split(CChar(","))(0), s.Split(CChar(","))(1))
_subGenreDropDown.Items.Add(li)
Next
Case "Vendor"
For Each s As String In _vendorSubGenres
Dim li As New ListItem(s.Split(CChar(","))(0), s.Split(CChar(","))(1))
_subGenreDropDown.Items.Add(li)
Next
Case "Div Docs"
For Each s As String In _trackSubGenres
Dim li As New ListItem(s.Split(CChar(","))(0), s.Split(CChar(","))(1))
_subGenreDropDown.Items.Add(li)
Next
End Select
End Sub
Private Sub _subGenreDropDown_ItemChanged(ByVal Sender As Object, ByVal e As System.EventArgs)
_txtBoxAutoCompleteExtender.ServiceMethod = _subGenreDropDown.SelectedValue.ToString
If _subGenreDropDown.SelectedValue.ToString = String.Empty Then _txtBoxAutoCompleteExtender.ServiceMethod = "PlaceHolder"
End Sub
Public Function createMyTableRow() As HtmlTableRow
Dim myRow As New HtmlTableRow
myRow.Cells.Add(New HtmlTableCell())
myRow.Cells.Add(New HtmlTableCell())
myRow.Cells.Add(New HtmlTableCell())
myRow.Cells(0).Controls.Add(_genreDropDown)
myRow.Cells(1).Controls.Add(_subGenreDropDown)
myRow.Cells(2).Controls.Add(_txtValue)
myRow.Cells(2).Controls.Add(_txtBoxAutoCompleteExtender)
Return myRow
End Function
Private Sub newAutoCompleteExtender(ByVal genre As String)
If _txtValue.Parent.Controls.Count = 2 Then
_txtValue.Parent.Controls.RemoveAt(1)
End If
_txtValue.Parent.Controls.Add(_txtBoxAutoCompleteExtender)
End Sub
End Class
Public Class SearchFilterGroup
Private _searchFilterCollection As Collection(Of SearchFilter)
Private _tableContainer As HtmlTable
Private _company As CompanyCode
Private _year As DocumentYearCode
Public WithEvents _addFilterButton As New Button
Public Sub New(ByVal company As CompanyCode, ByVal year As DocumentYearCode)
_searchFilterCollection = New Collection(Of SearchFilter)
_tableContainer = New HtmlTable
_company = company
_year = year
_addFilterButton.Text = "Add Filter"
_addFilterButton.Attributes.Add("runat", "server")
_addFilterButton.ID = "btnAddFilter"
AddHandler _addFilterButton.Click, AddressOf _addFilterButton_Click
End Sub
Public Sub _addFilterButton_Click(ByVal Sender As Object, ByVal e As System.EventArgs)
_searchFilterCollection.Add(New SearchFilter(_company, _year))
_tableContainer.Rows.Add(_searchFilterCollection(_searchFilterCollection.Count - 1).createMyTableRow)
End Sub
Public Function table() As HtmlTable
_tableContainer.Rows.Add(New HtmlTableRow)
_tableContainer.Rows(0).Cells.Add(New HtmlTableCell)
_tableContainer.Rows(0).Cells(0).ColSpan = 3
_tableContainer.Rows(0).Cells(0).Controls.Add(_addFilterButton)
_addFilterButton_Click(Nothing, Nothing)
_addFilterButton_Click(Nothing, Nothing)
Return _tableContainer
End Function
End Class
I am having problems devising a way to persist the generate controls. Any help would be appreciated.

Answer 1

Basically, for task which you do is better to create custom server control. In ASP.NET exist CompositeControl class which simplifies developing your own server controls which for example should include some other server controls (like panels, texboxes and etc) as children.
A very good link to start with creating your own server controls is Dino Esposito article: A Crash Course on ASP.NET Control Development: Building Composite Controls