I have a ASP.NET 1.1 application, and I'm trying to find out why when I change a ComboBox which value is used to fill another one (parent-child relation), two postbacks are produced.
I have checked and checked the code, and I can't find the cause.
Here are both call stacks which end in a page_load
First postback (generated by teh ComboBox's autopostback)
Postback call stack (broken)
Second postback (this is what I want to find why it's happening)
alt text (broken)
Any suggestion? What can I check?
It's a very specific problem with this code, I doubt it will be useful for someone else, but here it goes:
A check was added to the combo's onchange with an if, if the condition was met, an explicit call to the postback function was made.
If the combo was set to AutoPostback, asp.net added the postback call again, producing the two postbacks...
The generated html was like this:
[select onchange="javascript: if (CustomFunction()){__doPostBack('name','')}; __doPostBack('name','')"]
First thing I would look for is that you don't have the second ComboBox's AutoPostBack property set to true. If you change the value in the second combo with that property set true, I believe it will generate a postback on that control.
Do you have any code you could share? Double post backs plagued me so much in classic ASP back in the day that it was what finally prompted me to switch to .NET once and for all. Whenever I have problems like these for .NET, I go to every CONTROL and every PAGE element like load, init, prerender, click, SelectedIndexChanged, and the like and put a breakpoint.
Even if I don't have code there, I'll insert something like:
Dim i As Integer
i = 0
I am usually able to pinpoint some action that I wasn't expecting and fix as needed. I would suggest you do that here.
Good luck.
Check Request.Form["__EVENTTARGET"] to find the control initiating the postback - that may help you narrow it down.
Looking at the callstacks, and some Reflectoring (into ASP.NET 2 - I don't have 1.1 handy) - it looks like SessionStateModule.PollLockedSessionCallback is part of the HttpApplication startup routines. It may be possible that your app is being recycled - I'm pretty sure an event gets written into the Event log for that.
My only other suggestion would be Fiddler or something on the client to capture HTTP traffic.
This is very old post, but people still looking at this for solution exactly same as I did last week.
Like Grengby said Double events are primary reasons - but removing one of them is not allways an option. Atleast on my case and I had to resolve this on 3rd party's application.
I added following script and amended ASP form on masterpage:
<script>var Q = 0;</script>
<form id="Form1" runat="server" onsubmit="Q++; if(Q==1){return true;} else { return false;}">
This seems to be working and please forward your comments.
Arun
http://www.velocityreviews.com/forums/t117900-asp-net-multiple-postback-issue.html
Related
I'm generally an ASP.NET MVC guy, so the "standard" ASP.NET stuff is a little difficult for me to wrap my brain around. I've tried looking for the answer, but the keywords I'm using seem to be too generic... I get a lot of close answers, but not what I'm actually looking for.
I have a grid that is populated from a data set. One of the fields is a dropdown with 4 possible statuses. When the user selects a status, an event is fired in the codebehind to make the change in the db immediately.
There is a particular status that I need to confirm, because once it's selected, it's irreversible. Figuring out how to have the back end pop up a confirmation box was annoying, but I think I have that part done now.
The problem is, if the user confirms that the status they selected for the dropdown was intended, I need to disable any further changes to that dropdown, either by disabling the control or by removing the row altogether. With this requirement, I imagine I need to pass a reference to the specific control that fired the event back to the script, so that it can pass it through the postback, where I would need to consume it.
I have no idea how to pass a reference to the control (what can be used as a reference?) and I have no idea how to use that reference in the postback.
Any help would be greatly appreciated.
;p i was waiting for you to find my post on the issue lol.
but to put it simply, you postback to the page, all members are still available to you if you instantiated something in codebehind. if not, then use FindControl to pull them from DOM. here's the passing values stuff.
as long as you don't kill the lifecycle, you're fine: Passing dropdownlist selected value to another page's dropdown list
and here is the linkspam (full docs): How do I keep TCP/IP socket open in IIS?
probably the articles on session-state and page lifecycle will be of most use.
To prompt the user for confirm add this attribute to dropdownlist.
onchange="return confirm('Confirmation Message');"
I wish I could paste in my markup, but it's too complex and contains a lot of references to the client's company name. I am hoping someone with vast experience might be able to point me in the right direction.
We have a master page with a ValidationSummary that is not part of a validation group. On our content page, we have another ValidationSummary that is assigned to a validation group called ValReject. On the content page is also a CustomValidator that uses ClientValidationFunction and a button, both of which are also assigned to ValReject.
When I click the button, the client function executes once, but the error reports to both validation summaries, the one on the content page and the on on the master page. I even added a third validation summary and set its group to something like "asdf", but it gets reported to, as well, meaning all three validation summaries are showing the same error on the page.
I then created a separate ASP.NET test project, pasted all the code in, and ran it and it validates like it should.
I then played around with AutoEventWireup on the content page. When I set it to false, validation works, but the page load event doesn't fire. What's up with that?
I know you probably need code samples, but, like I said, I just can't do that without going through a huge headache (trust me, the master and content page markup is huge.
The question here is: Does anyone have an idea of what could cause a single validator to report to ALL validation summaries on the page even though only one of them shares the same validation group as the validator and button?
edit: When I pasted the markup into my test app, I did have to remove some tags to get it to work since the test app doesn't have references to some assemblies used by the real master page. Some things I removed are:
<%# Register Assembly="RadMenu.Net2" Namespace="Telerik.WebControls" TagPrefix="radM" %>
<radM:RadMenu ID="RadMenu1" runat="server" DataSourceID="smdsMenu" Skin="CssGrey" ClickToOpen="True" EnableViewState="False" CausesValidation="false" />
So the fact that it works on my test app leads me to the conclusion that we're doing something on our production app that I am not doing in my test app. Yes, I know this is vague, but perhaps a light bulb will go off in someone's head.
Man, after hours and hours of spinning my wheels, I finally figured it out. We use this extension method to disable double clicks of buttons:
public static void DisableDoubleClick(this Button Control)
{
System.Text.StringBuilder sb = new System.Text.StringBuilder();
sb.Append("if (typeof(Page_ClientValidate) == 'function') { ");
sb.Append("if (Page_ClientValidate() == false) { return false; }} ");
sb.Append("this.disabled = true;");
sb.Append(Control.Page.ClientScript.GetPostBackEventReference(Control, ""));
sb.Append(";");
Control.Attributes.Add("onclick", sb.ToString());
}
This is what was messing up the validation as it was invoking global validation. I fixed this by making the following change:
sb.Append(string.Format("if (Page_ClientValidate({0}) == false) {{ return false; }}}} ",
Control.ValidationGroup == string.Empty ? string.Empty : string.Format("\"{0}\"", Control.ValidationGroup)));
What clued me in was when I set AutoEventWireup to false to see what would happen. This kept the page load event from firing which is where the above extension method was being called. What a needle in the haystack, this problem.
I don't blame anyone for not answering due to lack of details, but I will keep this up in case anyone else can use it.
edit: Thanks to slfan and gbs. I had just figured out the issue and was coming back here to post my answer when I see that you two were essentially tackling my issue from both sides of the problem. The page load event is where the binding was occurring and the extension method being called was messing up the Page_ClientValidate function. Since you both are technically right and I can't award both of you the answer, I hope no one gets upset if I mark my own as the answer here. You two are definitely good at analyzing such issues with minimal details and no code samples. Props.
The AutoEventWireup causes ASP.NET to call the Page_Load event automatically without having to register to an event. An alternative could be to override the OnLoad method. Your page seems to work properly when Page_Load is not called. What do you do inside this method? Some strange data bindings? What if you uncomment this code, will it work then? Like this you could narrow your problem down to the real problem which you are not showing in your question.
Two things I would look for:
1: Any external validation using Page_ClientValidate being done in javascript
2: Any explicit call to Page.Validate() in code-behind
I'm really new to asp.net and have a couple of issues I'm trying to get fixed. I have some programming experience, but it is not asp.net. However, I've been able to follow the code enough to make other changes in the code to fix other issues.
The first is this:
I'm working with a form that has a calculate amount method that gets called when the user inputs a value in an amount text box. The same method gets called when the next control, number of payments, has a value.
So in the two controls:
onTextChanged="ctrlName_textChanged"
Then in the code behind, the textchanged method does:
calculateAmount();
The problem is after the amount is calculated and returns, the focus seems to get reset and the user has to tab all the way back through the form to the place they were.
The textboxes in question are in a panel that starts out hidden and is made visible conditionally.
My apologies if I have not used the proper .net terminology.
It looks like the same issue may be causing my second problem. When the user types in an amount and then tabs and quickly adds the number of payments, you can see the amount get calculated correctly and very shortly displays the proper total in the total amount text box. However, even though it shows for that short time, the tab order again gets reset as well as the total amount value.
I've looked at different methods to try and fix the focus issue.
In the textchanged method, I tried using something like:
Session["myval"] = "someval";
Then tried to check against that in Page_Load with something like:
if(Session["myval"] != null) {
this.NextControl_Name.Focus();
}
but it didn't ever work correctly.
I also tried to set a cookie in that same textchanged method using something like this:
Response.Cookies["myval"].Value = "somevalue";
Then tried to check that in Page_Load using something like the previous if block above but using Request.Cookies["myval"] as the source.
Is there a good reference with some really clear code samples I can look at for this type of implementation?
Thank you in advance,
C.
Sounds like you have a postback problem...
Remember that the web is stateless. This means that when you have a web page rendered out in .NET and you attach an event that executes serverside code... it does an HTTP POST back to the server which is effectively a new page request. The Page_Load method will fire again as well as your bound event. So your onTextChanged event is firing a new request back to the server. This is why you see the focus reset and why when you tab quickly, the value seems to disappear magically.
You can do one of several things, you can implement the UpdatePanel in the AjaxControlToolkit
http://www.asp.net/ajax/ajaxcontroltoolkit/samples/
you can use PageMethods and do your validation with javascript and jQuery (or other js library)
see page method info http://www.geekzilla.co.uk/View30F417D1-8E5B-4C03-99EB-379F167F26B6.htm
Hope this helps
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 have user control on a ASP.NET web page, which contains a GridView and a radio button selector.
In the underlying middle tier I have a thread which goes to the database and then raises an event to say "I have some data" my User control handles this event and sets a Session Variable.
This works and I can see the event being handled and the Session variable gets the new data.
However when i go to use this session variable when the selected index of the Radio button selector changes the Session variable reports as "Nothing"
I have ensured that the obvious (i.e. spelling, Sessions switched on etc) are correct.
The GridView and radio button selector are encapsulated in the same Update panel.
Check that if your UpdatePanel - updatemode is set to 'Conditional'? also Child as triggers? I would first start by putting a stop in your page load, see whats happening from there. Do a search for all places where you populate that session variable and put a stop. You may be surprised, I have often found that page lifecycle gets confusing even though I thought I understood it. Alt - post some code and we can step through.
Yeah, sounds almost like a problem with order of operations or not checking for postback on a page load or something?
Like JamesM suggested, running your website in debug mode should really help identify the problem. You can bring up your watch window and set it for the Session variable you're looking for, then set breakpoints all over and check the value at each stop to divide and conquer the code.