I want to set a breakpoint on the __DoPostBack method, but it's a pain to find the correct file to set the breakpoint in.
The method __DoPostBack is contained in an auto-generated js file called something like:
ScriptResource.axd?d=P_lo2...
After a few post-backs visual studio gets littered with many of these files, and it's a bit of a bear to check which one the current page is referencing. Any thoughts?
If you using IE7 for testing you can use View -> Script Debugger -> Break on next statement and then just click the button that generates the event(__DoPostBack)
TBH, I dont think there is much value in setting a breakpoint within the Javascript since it pretty much comes straight back to the server anyways.
It would be best to set breakpoints in your server code.. Depending on what you are trying to debug this will be in different places.. Either in the page event cycle or a controls IPostBackEventHandler.RaisePostBackEvent handler.
Related
Ok, so I am working on a custom framework above the .NET framework, and some instructions are not written / called at the good places.
For example, a postback is done on the same page. Then, a Response.redirect occurs right within the page_load; but at this point, the new values of the controls of the page are not yet handled, so they get lost...
Therefore, I wanted to know whether it was possible to force the pagelife_cycle to go forward before the call to response.redirect, so that I can get the right values.
I can't just make that call in another function, because the page I am working on is called by many web applications (about 1-2k), and it would completely change their behaviour, which is not acceptable!
Is that even possible?
See a bit the second image and the Load PostBack Data section. Before the Load event of the page is raised, a textbox is already initialized. You can catch the value by overriding OnPreLoad or by adding a handler at PreLoad event.
I am needing a piece of javascript to be run whenever a postback occurs. Well, actually multiple pieces. This is to be done inside a custom control, so the javascript code that should be run may be used a lot of times.
I currently have it so that the custom control will create a chain of "overrides" for the __onPostBack function. I feel this is pretty messy and it also does not handle regular post backs caused by Buttons.
tl;dr: What is the best way of executing a piece of javascript code when a postback happens? (that is, execute the code before the postback hits the server)
(Also, aiming for IE 7+ and Firefox compatibility)
You could set the onSubmit event on the form:
ClientScript.RegisterOnSubmitStatement(this.GetType(), "MyScript", "alert('Hello')");
Old and new way is described here: http://weblogs.asp.net/vga/archive/2004/03/01/NoMoreHijackingOfDoPostBackInWhidbey.aspx
I'm writing an asp.net web app. and i've hit a bit of a brick wall.
basically i have 2 pages, the main page with a text box in and a popup that contains a treeview.
My problem is this. when i select a treeview item i want the program to perform some database transactions using asp.net and then pass the value retrieved from the database into a javascript function that passes the data back from the popup page to the parent page. My problem is that i cannot find any way of calling a javascript function from asp.net. I've tried assigning attributes to controls on page load, but this does not work as when the page loads the data has not been retrieved from the database.
Have a look at the ClientScriptManager class. You can register scripts from code-behind that will run when the HTML page loads. Those scripts can call other javascript functions on the page.
There are many tutorials and examples on the Web. Here's one I found that may help but there are many more.
How to use the client script manager
You hit the nail on the head when you said "I've tried assigning attributes to controls on page load, but this does not work as when the page loads the data has not been retrieved from the database." You just need to discover when you're pulling the data from the database, and then assign the values after that. Without looking at your code, there's no way to know for sure, but Page_PreRender is probably a good bet to assign your values...it's probably after you're pulling information from the db...it's pretty much the last place that you can make things happen before the html is generated for the client.
You can invoke a function resided in the Main Page and call that function in the Main Page from the Child Page which is your pop up window.
Please refer to these links for references
http://chiragrdarji.wordpress.com/2007/03/10/call-parent-windows-javascript-function-from-child-window-or-passing-data-from-child-window-to-parent-window-in-javascript/
http://www.webmasterworld.com/forum91/2957.htm
http://hspinfo.wordpress.com/2008/01/12/call-parent-windows-javascript-function-from-child-window/
This one helps with retrieving popups from values using javascript
http://www.eggheadcafe.com/articles/20060117.asp
This one shows how to fire a postback using javascript, and manage it in the codebehind.
http://weblogs.asp.net/mnolton/archive/2003/06/04/8260.aspx
If you put them together, and use Control.ClientID to find the actual "html name" of your asp.net controls, you'll be able to set that up in no time.
Might not be the prettiest way to do it in town, and incidentally make little baby Jesus cry, but anyway, it works.
[edit]Oh. I just saw that it seems I answered the question the other way around, or "how to trigger codebehind from Javascript". I think the method I suggest may help you, if you use it right.
The javascript of the popup should pass the information to the parent window, and the parent window function should call a postback when it receives the information.
The javascript of the popup window should be only registered on a postback with the correct information retrieved, so that when the postback occurs on the popup because of the selection of the right information, the window closes and passes the information to the parent page.
The parent page, triggering postback, does the thingies you need it to, and the app resumes "normally" from there on, doing whatever you need it to, outside of the popup page.
I need the ability to temporarily turn off the partial page update behavior for an ASP.NET Ajax / UpdatePanel based page. (The reason is to circumvent the issue where IE blocks "automatic file downloads" for downloads generated as a result of this postback, but I don't want to distract from my original question)
I looked at the client side javascript libraries hoping to find a switch somewhere. I think a solution might involve using javascript to override the 'onclick' event handler for the control that acts as the trigger, and then calling "submit" on the form itself..
Also, using the EnablePartialRendering property on the server-side ScriptManager control won't work because that is done when the page is being built. I need to be able to do this as a result of switching a drop down list box.
Any ideas?
Cheers!
/ Sean
Well, after much trial and error, I found two approaches that seemed to work:
Use Javascript to manually submit the top level form associated with the page. This usually has the ID of "form1".
Create a button that is outside of any UpdatePanels and use Javascript to click the button.
I wound up using the second approach, since it allowed me to handle the event with a specific routine without the need to guess that my postback came from a Javascript call.
This is an example of the code that performed the postback:
...
if (isDownload) {
document.getElementById('FullPostbackSubmitter').click();
return;
}
...
Hope this helps someone else!
You can set the EnablePartialRendering property of your ScriptManager to false.
i was working on a vb.net project and i couldn't find some controls in the code-behind file(*.vb). i was wondering is it because i was working in page_load function so controls are not loaded until after page_control event. however i was able to find them with findcontrol function of formview objective.
Controls inside of templates (such as in your FormView, or in a GridView) are not directly accessible in the code behind. You must use FindControl to get access to those controls.
If the controls are declared in the aspx then they're defined in partial class equivalent for your Page class.
This was introduced along with .Net v2.0 so that messing with the designer wouldn't screw up with your code behind file (which caused quite a few problems in some cases).
You can access the controls from your Page Load event. Sometimes IntelliSense plays tricks on you and doesn't suggest the control. Just type it in. It will work. You can close the aspx page and open it again. Sometimes that fixes it. Or just restart Visual Studio if you're annoyed by it.
However, there are a few considerations if you are interested in accessing control data at certain times during the life cycle of the page.
Server controls have their own life cycle that is similar to the Page life cycle, but the order in which the event is triggered for the controls is as follows:
Init and Unload event for a control occurs before the event is raised for the container (bottom-up).
Load event for a control occurs after the event is raised for the container (top-down).
You can find a more detailed explanation of the Page life cycle events on MSDN.
It's hard to tell what exactly the problem is; it would help if you could post some code here.
I do have two guesses/suggestions:
If you have the problem that brentkeller is describing, what usually fixes this completely for me is deleting the aspx.designer.cs file, then right-clicking on the .aspx file and select "Convert to Web Application". This re-creates the designer file.
The control is inside a template like Jason Berkan suggested. If it's in a LoginView, for example, you would use .FindControl("controlId") on the LoginView.
The controls would be part of a partial class in the same solution. Just find all references for your class name.
I occasionally have trouble with adding a control to a page and the Intellisense not recognizing the control. The compiler also seems to not recognize the control and prevents the project from being compiled. It can be very frustrating and I really haven't figured out why.
Sometimes it helps to close the aspx page and its code file, sometimes closing Visual Studio and re-opening it works. Sometimes none of it works and I just try another way to get things done.
I don't know if this is what you're experiencing, but if so, it can definitely make you scratch your head and wonder what is going on.