How To Apply Delegate And BeginInvoke
Mar 12, 2010
I am working with .net 3.5 and making application in asp.net. I show some application which is make in C# in Windows form where i see following code in class level declaration
[Code]....
and following code in form load
[Code]....
and following code in some event
[Code]....
Now my problem is I am making application in asp.net code behind VB.net where I cannot how to apply all this in my application. I more confuse with Delegate and BeginInvoke. I read somewhere that to use BeginInvoke in VB you should use Ajax.
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Sep 24, 2010
I have been moving my application to be more AJAX-based. Currently I have a web service call where I use jQuery to gather some textbox (string) and checkbox (boolean) results and pass it to a web service. Everything works really well, the response time is super quick. The only downside that I can see to this is
1) you need to use jQuery, which will add to the user's download time - this doesn't really affect my application too much because I am using jQuery throughout the site
2) users can see the code and potentially try to hack the web service because they know where it is
I am most concerned with #2. I've been reading a lot about .NET web service calls, using IAsyncResult,
http://msdn.microsoft.com/en-us/library/2e08f6yc.aspx, and I am beginning to understand the 4 methods available in this article. However, is there extra bloat using this way compared to the jQuery web service call?If there isn't that much bloat or lag time using this method, I'd like to convert my application. Which one of these 4 methods is best in a scenario where I am just returning a small string value? The 4 methods in the article are to wait for EndInvoke itself, which from what I read is not recommended because this may block the first thread; and this should not be used on a service that affects the UI.Create a WaitHandle to wait for the 'OK' before EndInvoke is called Poll the IAsyncResult for .IsCompleted, using sleep() and a Do While until IAsyncResult.IsCompleted is true, then call EndInvoke Pass a delegate function to BeginInvoke to be called once the operation is complete.
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Nov 19, 2010
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Sep 2, 2010
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Feb 22, 2011
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Jan 6, 2011
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Jan 27, 2011
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Aug 9, 2010
I am getting this error and can't figure out how to resolve it. CS0123: No overload for 'UserInfoDataSource_Selecting' matches delegate System.Web.UI.WebControls.ObjectDataSourceSelectingEventHandler'.
<Fields>
asp:BoundField
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<asp:BoundField
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[code]...
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Oct 4, 2010
I created a control where other developers can create an instance and use. There is a button click in the control. How do I allow developers to plug in their own code in a certain part of my control? I am not sure if or how exactly to use a delegate or event in this scenario.
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Jun 5, 2010
I need to pass a value from the selected button in user control to the containing page. I have it working fine but only by using a bunch of if statements that strike me as ugly. Can't figure out how to use a switch statement which, I think, would be a bit less cumbersome. I'd welcome on how to clean up this code (obviously I'm new to delegates).
Here's the code:
User Control:
<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="DelegateUserControl.ascx.cs"
Inherits="Foobar.UserControls.DelegateUserControl" %>
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using System;
namespace Foobar.UserControls
{
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{
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[Code]....
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Jan 14, 2011
I have a server control that performs some logic. I'd love to provide a default implementation of this logic in the code of the control, but allow a developer to pass an alternate implementation of this logic in as a delegate, if they wish.
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Dec 1, 2010
I have a web app where a user will visit a page with a QueryString parameter passing the ID of the object I should retrieve.
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Currently these searches are all performed sequentially, however I'm thinking the best option might be to use delegates to be able to fire off the three or four searches required at once then use the results as they are returned.
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My research has indicated it will use the ThreadPool, so there shouldn't be too much overhead, but I'd like to know if anyone has implemented this kind of solution to a similar scenario on a high traffic site and seen good resutls from it?
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Mar 2, 2011
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Jul 5, 2010
I'm trying to program a site so object oriented as I am able to....To do this I found a Paging example on the net.....but written in VB - and I'm programming in C#.In the VB example there is a line:
[Code]....
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Jan 15, 2010
I have a gridview in my page, called "GridView1", and Paging is enabled.I want to create a handler for PageSelectedIndexChanged but i keep getting this error: No overload for 'PageSelectedIndexChanged' matches delegate 'System.EventHandler'
asp:GridView
ID="GridView1"
runat="server"
OnPageIndexChanged="GridView1_PageSelectedIndexChanged"
[code]...
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Oct 19, 2010
It highlights this bit of code:
<asp:DataList ID="DataList1" runat="server" DataKeyField="uniqueid"
protected void Page_Load(object sender, EventArgs e)
protected void DataList1_Load(object sender, DataListItemEventArgs e)
Label Label1 = (Label)e.Item.FindControl("Label1");
Label Label2 = (Label)e.Item.FindControl("Label2");
Label Label3 = (Label)e.Item.FindControl("Label3");
[code]...
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May 14, 2010
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May 19, 2010
I am getting this build error on the following line of code, and do not find anyhting wrong there.
public partial class _Default : System.Web.UI.Page
{
}
[code]...
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Oct 1, 2010
Got a user control that has a Listbox on it and I want to be able to pass the selected value back to the main page.
User Control code:[Code]....
Main page that has the user control: [Code]....
This is the error I get back and I've tried everything I know, but cannot sort it. Probably something stupid but I just cannot see it.
System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.NullReferenceException: Object reference not set to an instance of an object. at bookings_roomadmin.Page_Load(Object sender, EventArgs e)
in \serverd$InetpubwwwrootNETDevelopNewAppNewAppookings
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Nov 15, 2010
I'm trying to look up the TypeID for each row of data returned from my sqldatasource that is displayed in a repeater. But I keep getting this error: CS0123: No overload for 'rptSectionExperience_OnDataBinding' matches delegate 'System.EventHandler'I know I've looked up values from a datagrid before and programatically used the data.
<asp:Repeater
ID="rptSectionExperience"
runat="server"
OnDataBinding="rptSectionExperience_OnDataBinding"
DataSourceID="dsGetResults"
[code]...
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Jan 18, 2010
I have created a custom composite control basically with two checkboxes. I have created a subscribable event, and the consumer has subscribes to it. But when I go to excute it, the delegate reference is null. What am I missing and why is it losing its subscribed events?
[Code]....
I am using VS2008 SP1 targeting .Net 2/3.5SP1 web site.
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Apr 14, 2010
I have a control that handles commenting. In this control, I have set a delegate event handler for sending an email.
I then have various types of controls, e.g. blog, articles etc, each of which may or may not have the commenting control added (which is done dynamically with me not knowing the id's), i.e. the commenting control is added outside this control. Each of these controls handles it's emailing differently(hence the event).
What I'm trying to determine, is how to assign the event in the parent control. At the moment, I'm having to recursively search through all the controls on the page until I find the comment control, and set it that way. Example below explains:
COMMENTING CONTROL
public delegate void Commenting_OnSendEmail();
public partial class Commenting : UserControl
{
public Commenting_OnSendEmail OnComment_SendEmail();
private void Page_Load(object sender, EventArgs e)
{
if(OnComment_SendEmail != null)
{
OnComment_SendEmail();
}
}
}
PARENT CONTROL
public partial class Blog : UserControl
{
private void Page_Load(object sender, EventArgs e)
{
Commenting comControl = (Commenting)this.FindControl<Commenting>(this);
if(comControl != null)
{
comCtrol.OnComment_SendEmail += new Commenting_OnSendMail(Blog_Comment_OnSendEmail);
}
}
}
EDIT:
The reason I ask is that if I search from this.Page as the initial control, I am worried about time taken to search down the control tree to find it. Each different type of page would be different in how many control it would have. On some testing, it returns back quite quickly the result.
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Feb 17, 2010
I am getting an error on the return saying
Error 18 Cannot convert method group 'ToList' to non-delegate type System.Collections.Generic.List<string>'. Did you intend to invoke the method?
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