So I have a masterpage with a login that is in an update panel. I have a child page that has a literal control that should update when the login updates. What it doesn't do is reload the method I use to generate the content for that literal when it posts back. I tried to call the method on the child page from the master page once you click log in, but I get an error that the literal control cannot be found (because it exists on the child page not the master page). How would I reference that control in the masterpage to pass it to my method?
The article below shows how the control tree works with MasterPages and how to reference different controls at different levels of the control tree.
ASP.Net 2.0 - Master Pages: Tips, Tricks, and Traps
So the scenario is that you have an update panel on the child page that when triggered doesn't update/refresh your lets say, label which is in your header on your master page.
What you do is, in the code behind of your master page create a function that changes the value of the label.
Include an update panel on the master page for the label, which is triggered by the textchanged event etc.
Now, in your child page code behind or your let say, button click event, call upon the function that exists in the master page and send the needed value in the parenthesis.
C#:
((MyMaster)this.Page.Master).ShowMessage(text);
VB.NET:
DirectCast(Me.Page.Master, MyMaster).ShowMessage(text)
This should update the label with the correct value whilst triggering the update panel on the master page and thus refreshing your label as well.
I'm about to try this now for myself, wish me luck. :D
Related
I have the following case:
Page1.aspx this page has the master page master.aspx.
I have some code in the master page :
if (!Page.IsPostBack)
{
adjustServiceBar();
}
when i click any button in the Page1.aspxit enters the !Page.IsPostBack and execute the method !!
i want this method in the !Page.IsPostBack) only
One way to do this is to set a session variable and then check that variable to ensure your code will fire only once.
Another way is to set a hidden control on your form and play with its text or value property.
According to each scenario the solution may be very complex such as custom derived masterpages and pages that extend the current events functionality to suit your needs.
I believe it is more consistent to check for IsPostBack in content page. You can move this condition to Page1.aspx and expose adjustServiceBar() method in your master page, so that content pages can call it, like Master.adjustServiceBar().
I have a contest form that is a usercontrol, it sits on page that has several usercontrols on it. When a user clicks a button it displays this form which resides in usercontrol, the div (which is on the page) is hidden at first. The only problem I am running into is when the page post backs it hides the DIV even when there is an error. I need it to keep the DIV open if there is an error, the code logic for form validation is in the usercontrol so how could I access the DIV that is on the page? The page is a masterpage, we dont do any code logic in our masterpages, is there anyway to accomplish this without code on the masterpage?
Best way would be exposing some property that says if any error occurred on user control or not and setting the Div's visibility on page itself based on that user control property.
The Scenario: I have an asp.net website where I show a div popup on page load for taking a few user details. When a user inputs the details, or closes the popup, I set up a flag cookie so that the popup is not displayed again for the user. The div is in the MasterPage so that it is displayed no matter on which page a user lands first time. The div contains an UpdatePanel which has all the controls required for taking the details. This whole functionality is working fine.
The Problem: Now this div popup is not showing(by setting display:none) on subsequent postbacks(which I want), but the html markup is still loading with the page unnecessarily adding to the page size. What I would idealy want to do is: Check if flag cookie is set. If no, show the popup, else remove the popup's markup from the page.
Now since the div is not a server control, I cannot possibly remove it and the all the controls inside it. So, I thought of removing the UpdatePanel from the page:
protected void Page_Load(object sender, EventArgs e)
{
if (Request.Cookies["flag"] != null)
{
if (Page.Controls.Contains(updpnl_contact))
{
Page.Controls.Remove(updpnl_contact);
updpnl_contact.Dispose();
}
}
}
But I guess this tends to work with dynamically added controls only, and since the control is added at Design Time, it is not being removed.
Is there any way I can achieve this?
If you add a runat="server" attribute to your <div> element, it will be available in the code-behind. You'll need an id on it as well. Then you can just toggle the Visible property. If this property is false, the control won't be rendered to the client (i.e. no HTML markup).
What you're trying to do is not at all the usual workflow. I tend to think that it will not work as it would mess up control tree, maybe even corrupt the viewstate and so on.
As a possible solution, you can put it's visibility to hidden in the code behind. This, in the contrary to the usual 'gut feeling', doesn't work like the css propery 'display:none' for example - instead the control will not even be rendered into the page when it's not visible. This may be the workaround for you.
Happy coding.
A more efficient approach would be to create the panel as a UserControl and load it dynamically in codebehind when it's needed, then add it to your page. E.g, in code:
MyPopupControl popup = (MyPopupControl)Page.LoadControl("/path/to/usercontrol.ascx");
PopupPanel.Controls.Add(popup);
Where PopupPanel is an empty <asp:Panel>. Then, not even the markup will need to be loaded/processed except when its needed.
There is no reason that all the code you use to display and process this panel couldn't also be in the usercontrol, isolating it from the master page.
Can you build the panel dynamically, based on the cookie setting?
All the Google finds I ran into tell me how to use FindControl to access a control on the master from the content page itself.
However, what I'm trying to do is the opposite.
From the master page, I want to reference whichever child page is in the ContentPlaceHolder.
Why you ask.
I want the master page to know which tab should be active depending on the content Page currently in the placeholder.
This lets me avoid having each page to reference the master page and allow them to change the active tab; that should be the master page's job (if there's a way it can know whom it's enclosing).
Thanks. No rants please.
If you are looking to get the instance of the executing page class, you can retrieve it from the current HTTP context:
var page = HttpContext.Current.CurrentHandler as Page;
From there, you can navigate the page's control tree, call FindControl(), and so on. Be cautious about page lifecycle, though, as master page events tend to fire before their page event counterparts.
I'm fairly new to ASP.NET and trying to learn how things are done. I come from a C# background so the code-behind portion is easy, but thinking like a web developer is unfamiliar.
I have an aspx page that contains a grid of checkboxes. I have a button that is coded via a Button_Click event to collect a list of which rows are checked and create a session variable out of that list. The same button is referenced (via TargetControlID) by my ascx page's ModalPopupExtender which controls the panel on the ascx page.
When the button is clicked, the modal popup opens but the Button_Click event is never fired, so the modal doesn't get its session data.
Since the two pages are separate, I can't call the ModalPopupExtender from the aspx.cs code, I can't reach the list of checkboxes from the ascx.cs code, and I don't see a way to populate my session variable and then programmatically activate some other hidden button or control which will then open my modal popup.
Any thoughts?
All a usercontrol(.ascx) file is is a set of controls that you have grouped together to provide some reusable functionality. The controls defined in it are still added to the page's control collection (.aspx) durring the page lifecylce. The ModalPopupExtender uses javascript and dhtml to show and hide the controls in the usercontrol client-side. What you are seeing is that the click event is being handled client-side by the ModalPoupExtender and it is canceling the post-back to the server. This is the default behavior by design. You certainly can access the page's control collection from the code-behind of your usercontrol though because it is all part of the same control tree. Just use the FindControl(xxx) method of any control to search for the child of it you need.
After some research following DancesWithBamboo's answer, I figured out how to make it work.
An example reference to my ascx page within my aspx page:
<uc1:ChildPage ID="MyModalPage" runat="server" />
The aspx code-behind to grab and open the ModalPopupExtender (named modalPopup) would look like this:
AjaxControlToolkit.ModalPopupExtender mpe =
(AjaxControlToolkit.ModalPopupExtender)
MyModalPage.FindControl("modalPopup");
mpe.Show();
Sorry, but I'm confused. You can't call an ascx directly, so...
Is your modal code that you are calling from within the same page, like a hidden panel, etc;
Or is it another aspx page that you are calling on a click event?