How To Raise Events To Page From Dynamically Loaded User Control
Feb 23, 2010
I have user control that inherits a base control class and these user controls are loaded using the LoadControl method, I can't seem to figure out how to raise events from user controls to the page that are dynamically loaded this way. Here is the delegate and event in the base user control class.
public delegate void SomeChangeEventHandler(object sender
, SomeChangeEventArgs e);
public event SomeChangeEventHandler SomeChangeEvent;
public virtual void OnSomeChanged(SomeChangeEventArgs e)
{
if (SomeChangeEvent != null)
{
SomeChangeEvent(this, e);
}
}
For a "dashboard" module I need to dynamically load user controls based on criteria as the user enters the page (role, etc). The problem is that the events are not being fired at all from the controls
As I understand it I need to load the controls in the OnPreInit method of the dashboard page, however I cannot get a reference to the Placeholder control at this point of initialization (i.e. I get a NullReferenceException); trying to load the Placeholder dynamically via Page.FindControl gives me, ironically, a StackOverflowException.
I've tried loading the controls in PreRender and OnInit as well but the events in the controls are not wired up properly and will not fire.
protected void Page_Load(object sender, EventArgs e) { LoadMyControl(Parameters); //Do it every page load to preserve it's state } protected void LoadMyControl(string parameters) { plchld.Controls.Clear(); Control userControl = LoadControl("TheUserControl.ascx"); userControl.ID = "userControl1"; plchld.Controls.Add(userControl); }
Now inside this control, when a button is clicked I want to update ,let's say a Label on the hosting page. What is the best way to do it? Custom event?
I have created a web user control (MemberDetails.ascx) which is loaded dynamically on a page (Member.aspx) for my website. The control has some TextBoxes. I want to store the values inputted by a user in these TextBoxes to a database on the click event of a button that is on the Member.aspx page (i.e. not a part of user control).
I have created a user control that contains two asp calendar controls. I need to add this user control twice on the same asp page, let's say for Check in date and Check out date. Since the two are conflicting to each other when I add it twice statically, I now dynamically add them on button click so that each time only one control is loaded. The problem is, when I select a date on a calendar, it seems that the selection event is not happening at all. Of course, I am not getting any date.
I have a user control that contains a repeater. We have added some paging and sorting into the user control and it all works well.
What I need now is a nice way to catch the OnItemDataBound event of the inner repeater and then bubble it up to be accessible directly from the user control from within the page.
We have tried catching it and then declaring it in the user control but it just won't work.
I have a problem with ViewState. I have an aspx page that has a treeview on the left and an UpdatePanel with an ASP.NET Panel inside on the right. It is in that inner Panel where I load and unload dynamically user controls. I use that update panel to load dynamically controls.
I also made a custom control for my user controls because I need to pass some values from page. On that constructor I use ViewState to store these values.
The first time I load the user control I call its constructor with parameters. When I reload that user control on each postback I use its normal constructor.
My problem is I the values I've stored on ViewState has become null on successive postback.
Update:
This is a piece of my user control:
public class MyUserControl : System.Web.UI.UserControl { private int PKId { get { return ViewState["pkId"] as int; } set { ViewState["pkId"] = value; } } public MyUserControl(int pkId) { this.PKId = pkId; } ... }
I'm following this article to load controls dynamically: http://msdn.microsoft.com/en-us/magazine/cc748662.aspx#id0070065.
Second Update: I also set the same control ID when I load the user control at first time and on each reaload.
Maybe I can use another method to store these values like input hidden fields or Cache. I've choosen ViewState because I don't want to overload server with Session values for each user.
Third update:
I load the controls with this code:
System.Web.UI.UserControl baseControl = LoadControl(ucUrl) as System.Web.UI.UserControl; if (baseControl != null) { baseControl.ID = "DestinationUserControl"; PanelDestination.Controls.Add(baseControl); }
And reaload with this code:
DynamicControls.CreateDestination ud = this.LoadControl(TrackedUserControl) as DynamicControls.CreateDestination; if (ud != null) { ud.ID = "DestinationUserControl"; PanelDestination.Controls.Add(ud); }
What i did.........Created User Control like One.ascx with one button
<%@ Control Language="C#" AutoEventWireup="false" CodeFile="one.ascx.cs" Inherits="one" %> <asp:Label ID="Label1" runat="server" Text="Hello, this is My First User Control dynamically loaded :)"> </asp:Label><asp:Button ID="btnShow" runat="server" Text="Show" OnClick="btnShow_Click" /> On Code behind public void btnShow_Click(object sender, EventArgs e) {
[Code] .....
Fail to redirect user to google.com by clicking button which written in .ascx file.
I'm trying to make web form with two placeholders. Firs holder contains user control witch has list of buttons, each button opens different user control to second placeholder.
I get it to show user control in second placeholder but i can't get dynamically created user controls to fire events.
So how i can dynamically create working user control with button click?
Here is how i create those controls:
[Code]....
"field" is hidden field containing filename of user control to be created.
I have a aspx page, default.aspx, with an user control in it. Inside the user control (UC 1) there is a DataGrid. When the DataGrid is loading data with ItemDataBound, I need to dynamically load another user control (UC 2) for each row in the DataGrid. UC 2 has a Button ( BTN )with an eventhandler associated with it in code behind.
User control loading is fine, and the Button, BTN, is there. However, when I click the Button, the eventhandler is not reached, not firing, even though the page does postback. I googled for this issues, and I know the dynamically loaded user controls need to be loaded every time the page is postback. In my case, it needs to be loaded each time the datagrid is doing ItemDataBound. I did it and even hook up the eventhandler with button click event each time when the user control is dynamically loaded. I set EnableViewState to true on the Page and controls.
The following is part of the code from UC 1, AcctPaymentDetail is UC 2 in the code.
I have a blank user control (child) and during Page_Load i create some text boxes and a button. I also add an event to the button.
I then load that user control dynamically from a placeholder in another usercontrol (parent). Both controls are rendered correctly but when i click on the button, the event isnt fired. how to handle the event?
Child code:
[code].....
If i use the child control directy (ie without the parent the control) the click event is raised and handled nicely. But when i use the parent control, the debugger wont even hit a breakpoint inside UpdateButton_Click().
I have a tab control on my page and on click of tab user control is loaded dynamically.I need to load the javascript file of that user control dynamically. I don't want to add the reference of my js file on parent page.so in my .ascx page load event i added:
I have a login.ascx control with three controls (LoginName, Password and A Button) , I want to rase a click event on this button from .aspx page because some restriction is there so that I am unable to write any code on .ascx page.
I have assigned value on login name and password from .aspx onload events. but I an facing problem while rasing event on button.
I am showing code that I have written on .aspx page that I have putten onload section.
I have a user control that is dynamically added to a placeholder control inside an update panel in my main page. The user control has a linkbutton where I try to handle its Command event. The first time the link button is clicked after the user control loads, the form posts back but the command event handler does not execute, although the user control is still on the screen. The second and subsequent times the link button is clicked it works perfectly. When the user control first loads and I mouse over the link button, the browser status bar says: javascript: __doPostBack('ctl08$lbTest',''). After the first click, when I mouseover the link button the browser status bar shows javascript:__doPostBack('ctl07$lbTest',''). Why the changed in id, I can't figure but it must be why it is not hitting the event handler the first time it's clicked. Here is the cs code that loads the user control:
I'm developing an ASP.NET application with C# and Ajax.I have a page that holds user controls loaded dynamically. I need to pass some data (integer values and some strings) to the user control that has been loaded dynamically.Now I use Session to pass these values, but I think I can use another way; something like VIEWSTATE or hidden input.What do you recommend me?The fact that I load the controls dynamically is important because controls are loaded on every postback, and I can't store any value on controls.
I am trying to add dynamically a user control I created to an aspx page after it is loaded. I tried sending an ajax request to a handler that used RenderControl function and sent back the control's html. I appended it to the DOM using javascript.
The problem is that some of the controls must go through their Page_Load function and that doesn't happen when using RenderControl function.
In my default.aspx page I have a PlaceHolder control within an UpdatePanel. In this placeholder control I will dynamically load a web user control, which is just a form with a submit button. On this user control, I have the form within an update panel and I have the "Submit" button's Click Event added to the triggers.
When I submit the form, the UpdatePanel on the web user control nor the update panel on the default.aspx page are capturing the post back, thus causing a full post back which refreshes my page.
how to capture this post so its rendered in Ajax and not a full post back?
I have written a user control that captures some user input and has a Save button to save it to the DB. I use a repeater to render a number of these controls on the page - imagine a list of multiple choice questions with a Save button by each question.
I am loading the user control inside the repeater's ItemDataBound event like this (code simplified):
[code]....
The problem is that when the Save button is clicked, the page posts back, but lbnUpdate_Click is not called. The Page_Load event of the page itself is called however.
I should mention that the repeater is part of a user control, and that user control is loaded inside another user control (this is a DotNetNuke site which makes heavy use of user controls). The Save button link looks like this:
Is there any way for one user control to raise an event that is handled by another user control without going through the page? I am using Umbraco and do not have access to the page object.
--Edit--
Umbraco has the idea of Macro's (user controls) that it loads into pages. I can't access the page directly as this is part of the framework.
There is a publish subscribe (pubsub) pattern that I know would fit my needs well (2 user controls that need to talk to each other) but am unsure how to hook it up in ASP.Net without the page object.
I have an aspx webpage in which an user control is added dynamically as follows:
UserControl testUsrControl = LoadControl("TestUsrControl") as UserControl; testUsrControl.ID ="test";
Then I tried adding an event handler of user control inside aspx like below:
testUsrControl.Drpdatafield_SelectIndexChanged += new EventHandler(this.Drpdatafield_SelectIndexChanged);
But this line is giving error at **testUsrControl.Drpdatafield_SelectIndexChanged **. The error is "Drpdatafield_SelectIndexChanged" doesn't exist in UserControl.How can get the testUsrControl's events inside aspx page dynamically.
I have a login.ascx control with three controls (LoginName, Password and btnLogin) , I want to rase a click event on this button from .aspx page because some restriction is there so that I am unable to write any code on .ascx page.I am bale to put loginName and password on .ascx by using query string but unale to raise event.
