C# - Can Retrieve Data From Server To Client During An Asynchronous Post - Back Using Ajax Library
Apr 9, 2010
ASP.NET Ajax Library provides some client-side events. For instance:
Sys.Application.add_load(
function(args) {
// handle the end of any asynchronous post-back. Every-time there's
// a server round-trip, this method will be called.
}
);
During the asynchronous post-back I want to retrieve information to the client. This information must be available in some event like the discribed above.
Does the UpdatePanel or the ScriptManager have any server-side way to retrieve data back to client during an asynchronous post-back?
Being new to ASP.NET I have run into trouble building my own Whack-a-mole program. I think my problem comes from using Buttons, which by themselves send post backs to the server, making the software unusable. The looks are in place, making new buttons show up in the grid, in different places by random. However, when a button is pushed - the score doesn't change (which I feel is strange).
Not so strange is that the Button doesn't work since it sends post back to the server - reloading the UpdatePanel. I think I should use a different controller like the CheckBox and style it hard using CSS (which isn't a problem). Is this the correct way to go, or should I make use of JavaScript AJAX instead?
Note to self: This technique shouldn't be used in a public application since it put too much unwanted pressure on the web server.
I have a fileupload control in a web page. I upload one file to the fileupload control. I am having the path like c://images/image.jpg. But if change dropdown value,then i am losing the value in the fileupload control. How to get back the value?
I searched google and found asynchronise post back trigger is used if we want update panel to post back on some event of control if it is out side the update panel. Than what is purpose of post back trigger ?
I have two Repeater controls, each hosted in a user control. Both user controls are contained in the same aspx page. Only one User Control is visible at any one time. The repeaters are comprised of checkboxes, and text boxes for user input.
The aspx page is configured with an Ajax ScriptManager; and contains several Ajax UpdatePanels. These UpdatePanels result in partial page post backs when text is changed in a textbox control in controls on the aspx page (this is not the behaviour for the Repeaters in the User Controls). Through use of several AsyncPostBackTriggers, various controls contained in the other UpdatePanels on the page have their content refreshed in response to the partial page post backs they are configured be notified about.
Depending on a radio button group selection, I set the visible property to true or false - as appropriate for the User control containing a repeater control. The Repeater control is then populated with data using databinding. All of this works.
However, when the Submit button is clicked, the Repeater control contains no data.
Given that I am not dynamically adding the Controls containing the Repeater controls (but using Visible true / false). I would have thought that the State of the fields and the data in the visible control would be preserved during the post back.
The User Controls are contained within the UpdatePanel that contains the Submit Button.
I have explicitly Enabled View state without any effect.
Am I correct in assuming that I should not have to do any explicit handling of data changes the user makes (via client side script and manipulation of an Data Structure Representing the Repeater Data); and the View State should maintain the data I need to access on the server when submitted?
I do not believe that it is the User Control visible state changes that are causing the issue because when the page is initially loaded on of the User controls is populated with dummy rows (so it displays).
I am suspicious that because the visible state of the controls is changed during partial page post back, that the Page View State ends up with no knowledge of the User Control and therefore cannot track its data (or changes).
I am using Asynchronous File uploader ajax toolkit control.I want to get knowledge of whether page is posted back due to File uploader or not in Page_Load event of my aspx page.
For that i tried to use Page properties IsAsync, IsCallBack but even page is posted back on responce of File Upload these properties are false,only IsPostback property is True.
Why IsAsync and IsCallBack properties are false ?
I was thinking that since this control upload files Asyncronously, so atleast on File Upload IsAsync property should be True.But that is also false .
I have four textbox and a button in my page. After filling the textbox. When the user click save button. A loading image should be displayed. User should not feel that the page is postback to the server,Some thing like in facebook loading image.
(I think) with using a data bound Custom Control on the server to get hold of my data (it will be part of a larger dataset) and to ultimately pass updates to the database. The bit I'm researching at the moment is passing that data to and from the client.One way to pass the data to the client is to use JSON within the Pageload event to construct a set of Javascript objects (one per row in the data). Is that the best way, or am I missing something?
Then, after the data has been manipulated on the client, I need to pass the rows back again so that the server side code can pick them up and process the updates. I've seen a suggestion on here that a hidden text field is one way to do that. Is it the best?Neither of my approaches seem to be at all elegant - and I suspect that I am missing something fundamental in ASP .NET AJAX!
I have a simple question - I use update panel with custom server control inside. I call __doPostBack from javascript and RaisePostBackEvent on the server fires (I implement IPostBackEventHandler).This is client to server call. Could I return data back to the client (after this partial postback)? What is the best way to achieve this?
s is really old news, but I just found out today. I was watching a channel 9 video on jquery and wcf (http://channel9.msdn.com/shows/Devs4Devs/WCF-and-jQuery-A-Perfect-Couple) and the narrator said at the MIX conference that the Microsoft Client Library is dead and that jQuery is getting all those efforts. So I use the client side library at work. So my question is does this affect the UpdatePanel and it's client side events? The UpdatePanel control looks to be integrated into ASP.NET. I would prefer to not use it anyways because of well known performance issues, but my boss prefers it's simplicity
The ASP.NET runtime is meant for short work loads that can be run in parallel. I need to be able to schedule periodic events and background tasks that may or may not run for much longer periods.Given the above I have the following problems to deal with:
The AppDomain can shutdown due to changes (Web.config, bin, App_Code, etc.)
IIS recycles the AppPool on a regular basis (daily)
IIS itself might restart, or for that matter the server might crash
I'm not convinced that running this code inside ASP.NET is not the right thing to do, becuase it would allow for a simpler programming model. But doing so would require that an external service periodically makes requests to the app so that the application is keept running and that all background tasks are programmed with utter most care. They will have to be able to pause and resume thier work, in the event of an unexpected error.My current line of thinking goes something like this:
If all jobs are registered in the database, it should be possible to use the database as a bookkeeping mechanism. In the case of an error, the database would contain all state necessary to resume the operation at the next opportunity given.I'd really appriecate some feedback/advice, on this matter. I've been considering running a windows service and using some RPC solution as well, but it doesn't have the same appeal to me. And I'd instead have a lot of deployment issues and sycnhronizing tasks and code cross several applications. Due to my business needs this is less than optimial.
i want to get data from database of field Name and Gender, and then display it in Label name and gender. when i click save it move to next record and display name and gender that next record.
I add cascading drop down in a place holder during page load. When i submit the entire form, i found out that my drop down list is reload and my selected value is not selected.
The Item is applied for GridViewRow. This GridView is in a UpdatePanel, when I click a button to do a Ajax Post Back the CSS applied for the GridViewRow is useless (IE 6 only).
I'm working in a SharePoint application. I've a tree view control (Telerik) in my page where I load the children on demand. But after the partial postback the page title is getting disappeared (or showing some junk text which has couple of boxes(?)).
I am registering javascript after page post back using ScriptManager.RegisterStartupScript . it used to work previously. Ater there are some chagnes done in the project now it is not working. What might be the reason behind this. now i am unable to register the javascript after post back.
I have a custom server control (composite control having dynamically created dropdown boxes and textboxes). I have enabled AJAX in order to avoid page reload.The server control is used inside the ASP.NET webcontrol having few buttons which controls the visibility of the server control. Now I enter values in the dropdown box and texboxes and click on any other button. After this postback the last entered values are gone! The control is not remembering the values. How can I retain the values after post back?
There is a drop down list in the jquery ui modal form with id - drpAction.When the selection is changed I need to execute drpAction_SelectedIndexChanged function in the code behind. When I just try to invoke the function like onSelectedImdexChanged="drpAction_SelectedIndexChanged" ,the function is not fired.
I have a page that is mostly dynamically built in the page load of my VB.net code behind page.
The issue is that I made a change to the page and added a button that redirects to a secondary page. When the button is clicked there is a very noticeable lag until the button click event fires because the page is being rebuilt every time.
I had not wrapped the code in the load event in the If not ispostback.... because I have dynamic controls that the user interacts with and I need the page to be rebuilt when the user clicks them.
The dynamic controls are clickable table cells. I did some looking and I found that the RegisterPostBackControl. I thought this would be perfect but, it does not although I maybe using it incorrectly.
I have a page that the users get redirected to. On page load this page runs a bunch of code behind that and loads table. The processing could take a few seconds to minutes depending on how big a report is run. Is there any way to completely render the page before automaticly kicking off the code? I am trying to stay away from forcing the user to click on another button.
Basic concept of AJAX is to cause Partial post back of the Page. If we use AJAX, Page Load occurs, than what is the difference between normal Pages' Page_Load event (without ajax) and Page load event of a Page with ajax.
