ASP.NET (VB) How to Call a Sub on a .ascx page from a .aspx page?
I'm trying to set up a shopping basket on an ASP.NET (VB) site that I'm putting together.
The code I'm using for this is largely based on the sample website at the end of SAMS ASP.NET Unleashed 2nd Edition.
I have:
- a VB class file (Namespace="StoreComponent
- a .ASCX control which raises an instance of ShoppingCart and displays existing ShoppingCart items and provides buttons and events for removing items from the cart.
- a .ASPX page which includes the .ASCX control, alongside a repeater with items I would like to add to the basket.
What I would like to do is use a Button_Click event in the ASPX's repeater area to run a sub which collates product info and, in turn, runs a sub in the .ASCX control to add a new item to the basket and update the basket display.
A shortened version of the ShoppingCart.ascx code is below:
A shortened version of the Products.aspx code is below:
I can call the AddToBasket() sub from within the ASCX page based on events on the ASCX page themselves. However, I cannot get the AddToBasket() sub to be called from the script part of the .ASPX page.
The items I've Googled on this have left me with more questions than answers and tend to be C# examples (which I really struggle with)
Are there a few lines I can add or modify in my existing code to expose the Sub in the .ASCX file to the .ASPX file which uses this control?
The code I'm using for this is largely based on the sample website at the end of SAMS ASP.NET Unleashed 2nd Edition.
I have:
- a VB class file (Namespace="StoreComponent
- a .ASCX control which raises an instance of ShoppingCart and displays existing ShoppingCart items and provides buttons and events for removing items from the cart.
- a .ASPX page which includes the .ASCX control, alongside a repeater with items I would like to add to the basket.
What I would like to do is use a Button_Click event in the ASPX's repeater area to run a sub which collates product info and, in turn, runs a sub in the .ASCX control to add a new item to the basket and update the basket display.
A shortened version of the ShoppingCart.ascx code is below:
<%@ Import Namespace="StoreComponents" %>
<script runat="server">
Dim objShoppingCart As ShoppingCart
Sub Page_Load()
objShoppingCart = New ShoppingCart
BindDataGrid()
End Sub
Public Sub AddToBasket(ItemId As Long, PartCode As String, Brand As String, UnitPrice As Decimal)
objShoppingCart.Add(ItemId, PartCode, Brand, UnitPrice)
End Sub
Sub BindDataGrid()
dgrdShoppingCart.DataSource = objShoppingCart.Items
dgrdShoppingCart.DataBind()
End Sub
</script>
<asp:DataGrid ID="dgrdShoppingCart" runat="server"></asp:DataGrid>A shortened version of the Products.aspx code is below:
<%@ Page Language="VB" %>
<%@ Register TagPrefix="myControls" TagName="ShoppingCart" Src="~/ShoppingCart.ascx" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<script runat="server">
Sub Button_AddToBasket_Click(s As Object, e As RepeaterCommandEventArgs)
If e.CommandName = "cmdItemID" Then
Dim lngXrefId As Long
lngXrefId = Convert.ToInt64(e.CommandArgument)
'SOME CODE WHICH RETRIEVES THE VALUES FOR PartCode, Brand etc
AddToBasket(ItemId, PartCode, Brand, MatchBrand, Reference, MatchReference, UnitPrice)
End If
End Sub
</script>
<!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">
</head>
<body>
<form id="form1" runat="server">
<myControls:ShoppingCart runat="server" />
<h1>Parts</h1>
<asp:Repeater ID="rptPartsForUniqueModel" OnItemCommand="Button_AddToBasket_Click" runat="server">
<ItemTemplate>
<%#Container.DataItem( "PartCode" ) %>
<asp:Button Text="Add to basket" CommandArgument=<%#Container.DataItem( "ItemID" ) %> CommandName="cmdItemID" runat="server" /></ItemTemplate>
</asp:Repeater>
</form>
</body>
</html>I can call the AddToBasket() sub from within the ASCX page based on events on the ASCX page themselves. However, I cannot get the AddToBasket() sub to be called from the script part of the .ASPX page.
The items I've Googled on this have left me with more questions than answers and tend to be C# examples (which I really struggle with)
Are there a few lines I can add or modify in my existing code to expose the Sub in the .ASCX file to the .ASPX file which uses this control?
ASKER CERTIFIED SOLUTION
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ASKER
Hm. Nearly there I think. However, when I run it, I get the following error message:
Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="tru
I'll have a go at tweaking the <%@ Page code to accomodate this...
Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="tru
I'll have a go at tweaking the <%@ Page code to accomodate this...
Hello, when the "Invalid postback or callback argument" exception is raised? what you do?
ASKER
The page displays fine.
I get an (empty) basket displaying with just the datagrid headers FROm my ASCX control.
I also get the buttons from my repeater displaying.
When I click on a button in the repeater, that is when the error message occurs.
I get an (empty) basket displaying with just the datagrid headers FROm my ASCX control.
I also get the buttons from my repeater displaying.
When I click on a button in the repeater, that is when the error message occurs.
ASKER
I've got to go to a meeting now - be back in an hour or so - this error message seems to be fixed by adding <%@ Page EnableEventValidation="fal
Hello, I don't recommend to disable EnableEventValidation, in the code that you are showing all look fine, that error should not be occur... the only observation, missing quotes when you set the CommandArgument binding, but I dont think that raises the error:
<asp:Button ID="Button2" Text="Add to basket" CommandArgument='<%# Container.DataItem("ItemID") %>' CommandName="cmdItemID" runat="server" /> Public Sub AddToBasket(ItemId As Long, PartCode As String, Brand As String, UnitPrice As Decimal)
objShoppingCart.Add(ItemId, PartCode, Brand, UnitPrice)
BindDataGrid()
End Sub
Also, I recommend you to html encode the text that you write from your db to your item template, example:
<asp:Repeater runat="server" ID="rptPartsForUniqueModel" OnItemCommand="Button_AddToBasket_Click">
<ItemTemplate>
<%# Server.HtmlEncode(Container.DataItem("PartCode").ToString())%>
<asp:Button runat="server" ID="Button2" Text="Add to basket" CommandName="cmdItemID" CommandArgument='<%#Container.DataItem("ItemID") %>' />
</ItemTemplate>
</asp:Repeater>ASKER
Hm.
I've tried a few things now with mixed results.
1) Changed the CommandArgument= to include apostrophes ' '
2) Added the BindData() call to the AddToBasket() sub
3) Added a button and btnClick sub within the ASCX code which calls the AddToBasket sub with a few dummy values for the arguments.
Now, with <%@ Page EnableEventValidation="fal
The button within the .ASCX code behaves as expected. Clicking on it adds a new item to the basket and clicking it again increments the count of items by 1.
The buttons within the .ASPX code, when clicked, cause the page to flicker, do not cause errors, but do not seem to affect the basket contents.
When I change the PAGE directive back to <%@ Page EnableEventValidation="tru
I think this is now two different problems - the page event validation is one problem, the failure of the ASPX button to run the sub in the .ASCX control is another.
For testing purposes, I'm happy to override the event validation in the PAGE directive and look more closely at this later.
I've tried a few things now with mixed results.
1) Changed the CommandArgument= to include apostrophes ' '
2) Added the BindData() call to the AddToBasket() sub
3) Added a button and btnClick sub within the ASCX code which calls the AddToBasket sub with a few dummy values for the arguments.
Now, with <%@ Page EnableEventValidation="fal
The button within the .ASCX code behaves as expected. Clicking on it adds a new item to the basket and clicking it again increments the count of items by 1.
The buttons within the .ASPX code, when clicked, cause the page to flicker, do not cause errors, but do not seem to affect the basket contents.
When I change the PAGE directive back to <%@ Page EnableEventValidation="tru
I think this is now two different problems - the page event validation is one problem, the failure of the ASPX button to run the sub in the .ASCX control is another.
For testing purposes, I'm happy to override the event validation in the PAGE directive and look more closely at this later.
Hello, I dont have the full view of your aspx page code... let me see if I understand:
1. Now, when you click the button "Add to basket" inside your repeater, it works, add the item to your shopping cart and refresh the ShoppingCart control content.
2. You have another button (outside your repeater control) in your aspx page (does not appear in your sample code) that must add an item to your ShoppingCart control too, but it is not working.
I'm right about that?
1. Now, when you click the button "Add to basket" inside your repeater, it works, add the item to your shopping cart and refresh the ShoppingCart control content.
2. You have another button (outside your repeater control) in your aspx page (does not appear in your sample code) that must add an item to your ShoppingCart control too, but it is not working.
I'm right about that?
ASKER
Sorry, No.
A single button in the user control (ASCX page) works. (I have added this since I sent the original code)
The buttons in the repeater portion of the .ASPX page do not work
Let me recheck my code for a few hours.
I've set up a really simple test to check your original suggestion - and it works (see sample code below)
I need to extend it to match my real code to see where the problems start.
Test.ascx:
A single button in the user control (ASCX page) works. (I have added this since I sent the original code)
The buttons in the repeater portion of the .ASPX page do not work
Let me recheck my code for a few hours.
I've set up a really simple test to check your original suggestion - and it works (see sample code below)
I need to extend it to match my real code to see where the problems start.
Test.ascx:
<%@ Control Language="VB" ClassName="Test" %>
<script runat="server">
Sub DisplayTime()
lblTime.Text = Now()
End Sub
Protected Sub UpdateTime(sender As Object, e As System.EventArgs)
DisplayTime()
End Sub
</script>
<asp:Label ID="lblTime" runat="server" /><br />
<asp:Button ID="btnControl" OnClick="UpdateTime" Text="Update Time (Within ASCX Control)" runat="server" /><%@ Page Language="VB" %>
<%@ Register TagPrefix="myControls" TagName="Test" Src="~/Test.ascx" %>
<!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 Button_Aspx_Click(sender As Object, e As System.EventArgs)
myTest.DisplayTime()
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<myControls:Test ID="myTest" runat="server" />
<br />
<asp:Button text="Update Time (Within ASPX Page)" runat="server"
onclick="Button_Aspx_Click" />
</div>
</form>
</body>
</html>
mm ok, please verify that your method Button_AddToBasket_Click is called when you click on the buttons inside your repeater:
I have made a test page with the repeater and everything work as expected, what .net version are you using?
Sub Button_AddToBasket_Click(s As Object, e As RepeaterCommandEventArgs)
Response.Write("Yes Button_AddToBasket_Click was called")
End SubI have made a test page with the repeater and everything work as expected, what .net version are you using?
Observation, in your last example you need to expose the DisplayTime method of your control as Public:
Also, try adding the protected access modifier to your Button_AddToBasket_Click method:
<%@ Control Language="VB" ClassName="Test" %>
<script runat="server">
Public Sub DisplayTime()
lblTime.Text = Now()
End Sub
Protected Sub UpdateTime(sender As Object, e As System.EventArgs)
DisplayTime()
End Sub
</script>
<asp:Label ID="lblTime" runat="server" /><br />
<asp:Button ID="btnControl" OnClick="UpdateTime" Text="Update Time (Within ASCX Control)" runat="server" />Also, try adding the protected access modifier to your Button_AddToBasket_Click method:
Protected Sub Button_AddToBasket_Click(s As Object, e As RepeaterCommandEventArgs)
Response.Write("Yes Button_AddToBasket_Click was called")
End SubASKER
I added the response.write line but it does not write anything to screen.
The problem seems to be that button clicks from repeater objects seem to be treated differently to plain asp:button items.
The attached code is a proper example of what happens, using a repeater:
The problem seems to be that button clicks from repeater objects seem to be treated differently to plain asp:button items.
The attached code is a proper example of what happens, using a repeater:
<%@ Page Language="VB" %>
<%@ Register TagPrefix="myControls" TagName="Test" Src="~/Test.ascx" %>
<%@ Import Namespace="System.Data" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
Sub Page_Load()
Dim array As String() = {"un", "dois", "tres"}
Repeater1.DataSource = array
Repeater1.DataBind()
End Sub
Public Sub Button_Aspx_Click(sender As Object, e As System.EventArgs)
myTest.DisplayTime()
End Sub
Sub Button_AddToBasket_Click(s As Object, e As RepeaterCommandEventArgs)
myTest.DisplayTime()
End Sub
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<myControls:Test ID="myTest" runat="server" />
<br />
<h2>Simple Button Area (in the ASPX code)</h2>
<asp:Button Text="Update Time (Within ASPX Page)" runat="server" OnClick="Button_Aspx_Click" />
<br />
<h2>Repeater Area</h2>
<asp:Repeater ID="Repeater1" OnItemCommand="Button_AddToBasket_Click" runat="server">
<ItemTemplate>
<asp:Button ID="Button1" Text="Update Time (From Repeater)" runat="server" /></ItemTemplate>
<SeparatorTemplate>
<hr />
</SeparatorTemplate>
</asp:Repeater>
</div>
</form>
</body>
</html>SOLUTION
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ASKER
The original answer was the right one but with my sample code, it needed that final answer to get it to work.
Many thanks for all of your help!
Many thanks for all of your help!
Glad to help
ASKER
I'm just going to spend 20 minutes putting some dummy data in to get it to test it but I think this solves my problem. If so, I'll accept this as the solution and award the points.