The Asp.Net's ajax implementation using UpdatePanel is really slow and experienced people know that the whole ViewState is sent to server even though we are only interested in doing partial postback. So I started using Jquery but I don't know how do I make a request from Jauery to server and get UserControl's HTML in output? The UserControl in turn may have some controls like textbox etc.
In short, I want some functionality that Asp.Net MVC has which uses RenderPartial.
In the context of Page, you can load a control and render its output.
Control myControl = Page.LoadControl("myControl.ascx");
myControl.RenderControl(System.Web.UI.HtmlTextWriter);
But that just gets the html that the control would output to the page. This is fine if your control has no more events and just does something onload, but if you want to postback from it, then this will not work (as mentioned in the comments.)
From my experience, sometimes ago, trying to invoke a user control directly is a pain.
I sometimes put my userControl in a blank page and simply do a $.get(
So, for each userControl, I have to make a dedicated blank page...
Other times, the userControl is already embedded in an existing page within a named div container. I then invoke $.load( on the page, targetting the container div.
In this case, I don't have to make a page, but I waste bandwith and lose script and style tags (jQuery cleans them up since v1.4)
Related
I'm starting to believe there is no way for me to interact with asp controls from within a webmethod. I wouldve thought i could some how accomplish this, by finding the page the webmethod was called from, and from there find and update controls on the page.
But after having an open question for 3 days and numerous google searches, it seems that there is no way for me to do this.
Or is there? I would really appreciate if someone could provide some useful information for me on this matter.
The problem is quite simple from a perspective.
1. I'm calling a webmethod through ajax, this is happening on say page A.
2. After a succesful ajax call, i wish to update an ASP control on page A.
3. The update of the ASP control must happen without a postback hence the ajax.
Is this really impossible?
Also if you know anything about this matter, but you don't understand my question, please have a look at my other active question: Update object on masterpage through ajax webmethod
When you call a webmethod, what happens is quite different compared to a button click for example in asp.net webforms.
The webmethod doesn't construct all the controls as a standard click event does.
So that's why you can't have access to the page controls.
Also, how would this work even if you had that access? Your webmethod only sends back some data, not the entire html code, so there's no way to update a control's value server side, since it has to be rendered in html.
If you want to update the value of a control on the client side (webbrowser), you can only do it via javascript when you receive the result of your webmethod. You only have to find the control by its id, and update its value.
For more information, you can look at this post:
What's the ASP.NET Webservice request lifecycle?
Another way to achieve what you want to do is to use the UpdatePanel. I personally don't like it, but it lets you access all the controls that are inside it, and update their values.
This control takes care of the client side update via javascript (but it actually replaces big parts of html in the page so it might be quite slow)
Calling a web method via AJAX has no impact on the HTML that has already been rendered to the browser.
What you'll need to do is return some information from your web method, and when the AJAX call completes, use jQuery to modify the appearance of the screen using the new information.
If what you're doing in the web method would result in a big change, one that you couldn't easily make happen in jQuery (such as re-rendering a GridView) you might want to look at UpdatePanels.
Problem:
I am loading one of several user controls based on a selected tab within RadTabstrip Control which is on the parent page. I've captured the Selected Tab and assigned it to a Session variable within the OnTabClick event to use in each User Control to determine if that particular control needs to be rendered.
The reason for this is because each User Control queries a database to render different charts and I don't want unneccesary processing occuring on every post back to the server. I'd like to add that each User Control has several Labels in their Markup that only gets the Text values assigned during runtime based on the content retrieved from the database.
When I load the main page, the selected tab variable is checked by each User Control and everything works fine from that scope. (The first tab at index 0 has no Charts)
Problem is when I select a Tab which has a User Control, the appropriate code to acquire the data from the database and build the chart works fine but the TEXT value of the Label controls in the Markup don't show up on the Page, although the TEXT values are being set in the Code-Behind at the same time the data is being retreived.
If I perform a Post Back of the same page, the TEXT values of the Label controls appear.
I believe this is because the 1st stages of the Page Life Cycle which include the rendering of the Markup aren't firing on the initial loading of the User Control, but get fired on subsequent Reloads or Refreshes of the Page.
Is there a way to work around this? I am figuring a call to the Render event after hitting the database would work but I may be way off base on my thoughts.
Can anybody provide some advice or a potential solution???
Thanks
I was never able to resolve the late binding issue which prevented the text of the labels from appearing until after a manual refresh of my page so I approached the issue from a different angle. I still retained the logic that only allowed the data of each User Control to get populated if their corresponding Tabs were selected by the user, but I moved the in-line code which was embedded in my Markup to my Code-Behind file.
I was not 100% certain as to the order that the mark-up vs. the code-behind got processed, so I researched and found that anything done declaratively in the aspx page is processed first, and the objects are created before being accessed or updated in the code behind.
So with this information I totally separated the two and was able to get the Text to render on the labels without any issue.
I still would haved liked to have known the appropriate way to force a page to call the Render event to simulate or mimick a manual Postback after the initial Page_Load, but going with the flow of the Page Cycle is the much easier and probably a more preferable way to do things.
One way to approach your problem is to consider use of the "Update Panel". It will allow you to render the entire page and then on an event only refresh the area of the update panel.
Generally I would love this feature for performance reasons but there is a catch. Some browsers (e.g. versions of Safari and Opera) do not render these correctly. Is your application a web application intended for general use by consumers? If so you may need to consider a full page refresh on the same page and pass the user data (unless Opera / other browsers have fixed this shortcoming - I have not tested in in 4 months).
I'm looking to optimize pages within our application so they perform better. I want to dynamically add controls (Textbox, Button, Custom Control, etc) to a page using AJAX to minimize postbacks done. I'm looking for an alternative to using an UpdatePanel (nothing wrong with them, they're just not built for performance).
The trick though is that the ViewState will need to be updated with the new controls added, so I can't see WebServices or static Page Method calls fitting in well here.
Ajax calls cannot update viewstate as that is created in code behind.
Maybe if you manage to access the viewstate server side you could send it back in the ajax call and store it in the viewstate field but you risk loosing anything that was not touched in the callback, I have never delved that deep into viewstate.
What I am trying to do is create a bit of reusable code that can write a modal popup, either through javascript or using the ajaxcontrol toolkit all from the code behind.
The modal would be a sort of login pop up for controlling access to more restricted areas of the website allowing certain users to re-credential in for higher access.
I was thinking of doing a user control but I forsee some problems with passing all of the appropriate information along without it being completely hoaky.
If anyone has any good links or advice for doing so it would be greatly appreciated!
Thanks!
EDIT: I know how to use the ajax control toolkit and its controls, and I know how to make login screens, I'm asking how to do this entirely from the code behind from a class that would be independent of its implementation
Write a server control or an asp.net extender control like ajax control toolkit does.
The best you can do is download the source of AjaxControlToolkit from CodePlex and explore the source of ModalPopup within that.
Another thing you can do is just simply call the popupExtender to show from the code behind file.
As we know the extender has to be somehow linked to a target control, just add a dummy control as a hidden textbox (actually to hide the control, do it from the asp file, as style="display:none" not from the control properties (visible=false) otherwise it won't work), and then just call from the code behind the extender like this:
DummyTextBox_ModalPopupExtender.Show();
You can call it in the page_load or with anyother trigger.
No need javascript neither client side, just, server side.
Xds.
There's a sample modal popup using the ajaxtoolkit on asp.net
The modalpopupextender in the Ajax control toolkit is easy to use, plus it has a server or client side method for showing the popup (in past versions, I had trouble with the server-side method, but it may have been resolved in the current version).
You could put the modalpopupextender inside the master page, and create a JS method in the master page you can call to invoke the modal popup extender, like:
function showPopup() {
var modal = $find("<%= mpe1.ClientID %>");
modal.show();
}
The contents of the popup can be replaced via javascript, as you control that content.
Add BehaviorID="my_cool_id" to your modalpopup extender and add this to any server function
ScriptManager.RegisterStartupScript(Page, this.GetType(),"id","function pageLoad(){$find('my_cool_id').show();}",true);
I have an ASP.Net page that is contained within an iframe the page has an update panel, that, in isolation, works however when the page is within the iframe, the update panel always produces a full postback. I guess that the problem is the iframe itself but id like to know
a) why it doesnt work
b) if there is a solution beyond rolling my own controls and writing a whole load of js
EDIT
ok its ASP.Net 2.0 and the 1.0 toolkit the page broadly looks like this (Note for the pedants i haven't closed tags, this is just to show the basic structure)
Main Page
Form
table
td
iFrame
! -- contained page --
Form
asp:ScriptManager
asp:UpdatePanel
asp:Repeater
I have been using some of my pages in IFrames using UpdatePanel, and they DO NOT produce any full page postbacks.
Can you describe the whole setup in more detail?
EDIT: Hmmm. The setup looks OK. Did you check whether the control which triggers the postback is placed inside the panel? Also, did you check for JS errors occuring before the ajax request fires?
Today I came across the same problem (trying to load gridviews asynchronously): A postback inside an iframe would reload the whole page, and ignore the postback event handler.
My solution was to use UFRAME.