Passing variable from .aspx to .ascx.vb

mister_mister · March 25th, 2008, 05:37 PM

I'm trying to pass a variable from an .aspx page to my custom user control on an .ascx.vb page. I have the 3 files below:

[u]homepage.aspx

Code:

<%@ Page Language="VB" MasterPageFile="~/templates/level_two.master" %>
<%@ Register Src="calendar_control.ascx" TagName="CustomCalendar" TagPrefix="CAL" %>

<script runat="server">
  '?????????
  'Initialize an integer variable here to use in "calendar_control.ascx.vb"
  '?????????
</script>

<asp:Content ID="levelTwo" ContentPlaceHolderID="levelTwo" Runat="Server">
  My Custom Calendar<br />
  <CAL:CustomCalendar id="EventList" runat="server"></CAL:CustomCalendar>
</asp:Content>

[u]calendar_control.ascx

Code:

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="calendar_control.ascx.vb" Inherits="CustomCalendar" %>
<asp:Xml ID="Xml1" runat="server" TransformSource="../XmlFiles/event_list.xsl"></asp:Xml>

[u]calendar_control.ascx.vb

Code:

Partial Class CustomCalendar
    Inherits System.Web.UI.UserControl

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim connect As New EkDb
        Using connection As New Data.SqlClient.SqlConnection(connect.connectionString)
            connection.Open()

            '??????????
            'Accept an integer variable from "homepage.aspx"
            'so I can use it in my SQL query.
            '??????????

            connection.Close()
        End Using
    End Sub
End Class

Is something like this possible?
Thanks!
Steve

dparsons · March 25th, 2008, 06:12 PM

Yes but you can do this where you drop the control on the page.

Add this to your ascx.vb page

Private _SomeInteger as Integer
Public Property SomeInteger() as Integer
Get
Return _SomeInteger
End Get
Protected Set(ByVal Value as Integer)
_SomeInteger = Value
End Set
End Property

then on your page:

<CAL:CustomCalendar id="EventList" SomeInteger="1" runat="server"></CAL:CustomCalendar>

You can then access the value inside your user control class by calling either _SomeInteger or SomeInteger()

hth.

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mister_mister · March 26th, 2008, 10:02 AM

thanks for the response, however it still doesn't seem to work:

[u]homepage.aspx

Code:

<%@ Page Language="VB" MasterPageFile="~/templates/level_two.master" %>
<%@ Register Src="calendar_control.ascx" TagName="CustomCalendar" TagPrefix="CAL" %>

<asp:Content ID="levelTwo" ContentPlaceHolderID="levelTwo" Runat="Server">
  My Custom Calendar<br />
  <CAL:CustomCalendar id="EventList" CalendarId="18" runat="server"></CAL:CustomCalendar>
</asp:Content>

[u]calendar_control.ascx

Code:

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="calendar_control.ascx.vb" Inherits="CustomCalendar" %>
<asp:Xml ID="Xml1" runat="server" TransformSource="../XmlFiles/event_list.xsl"></asp:Xml>

[u]calendar_control.ascx.vb

Code:

Partial Class CustomCalendar
    Inherits System.Web.UI.UserControl

    '????????????????
    'Changing "Private" to "Public" below doesn't do anything.

    Private _CalendarId As Integer
    Public Property CalendarId() As Integer
        Get
            Return _CalendarId
        End Get
        Protected Set(ByVal Value As Integer)
            _CalendarId = Value
        End Set
    End Property

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        Dim connect As New EkDb
        Using connection As New Data.SqlClient.SqlConnection(connect.connectionString)
            connection.Open()

            '????????????????
            'The value of _CalendarId and CalendarId() is always zero.

            Response.Write(_CalendarId) 'Outputs "0"

            connection.Close()
        End Using
    End Sub
End Class

What am I missing here?
Thanks!
Steve

dparsons · March 26th, 2008, 10:17 AM

Hmm I am not sure. I threw this together real quick and it works as expected (in C# though)

Default.aspx

Code:

<%@ Page Language="C#" AutoEventWireup="true" MasterPageFile="~/MasterPage.master"  CodeFile="Default.aspx.cs" Inherits="_Default" %>
<%@ Register Src="web1.ascx" TagName="web1" TagPrefix="uc1" %>

    <asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="server">
    <uc1:web1 ID="Web1_1" Foo="2" runat="server" />
    </asp:Content>

Default.aspx.cs is empty

web1.ascx

Code:

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="web1.ascx.cs" Inherits="web1" %>

web1.ascx.cs

Code:

    private int _foo;
    public int Foo
    {
        get { return _foo; }
        set { _foo = value; }
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        Response.Write(_foo.ToString());
    }

Default.aspx writes the value 2 to the screen??

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mister_mister · March 26th, 2008, 10:28 AM

hmmm, should nested master pages make any difference? it seems like this should work.

dparsons · March 26th, 2008, 10:36 AM

I don't see why it would. The usercontrol should act dependant of all the other controls and just because it is within a nested MasterPage shouldn't affect its execution. Of course there could be an issue with this that I am unaware of.

Can you see your property in Intellisense? Try this in your page load:

EventList.CalendarId = 5

Does that make a difference?

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mister_mister · March 26th, 2008, 10:47 AM

that's wierd - Inetllisense doesn't even recognize EventList?

dparsons · March 26th, 2008, 10:59 AM

Hmm. If I remember correctly VS doesn't have design time support of Nested MasterPages which may be causing the issue with Intellisense not picking up the control reference (it still seems weird though). Regardless, if you call EventList.CalendarId = 5 in the page load of Default.aspx does your application build?

I would also set a break point on your property to see if it is even being hit.

BTW, in your post you said that changing Public to Private doesn't do anything when, in fact, it does quite a bit. If you were to set the property to Private you wouldn't be able to access it outside of your control. By using the keyword Public that exposes to all of the other classes within your application.

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mister_mister · March 26th, 2008, 11:07 AM

the "calendar_control.ascx.vb" page_load is definitely being hit as i can output other variables.

on "homepage.aspx" when i add the following code, my page doesn't compile:

Code:

<script runat="server">
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)
        EventList.CalendarId = 5
    End Sub
</script>

this throws and error on the "EventList.CalendarId = 5" line above:

Code:

Compiler Error Message: BC31102: 'Set' accessor of property 'CalendarId' is not accessible.

and thanks for the explanation of public version private - good to know.

steve

dparsons · March 26th, 2008, 11:11 AM

Change Protected Set to Public Set. >< This was my fault in my original code.

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Read this if you want to know how to get a correct reply for your question:
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Wrox Books 24 x 7
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