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
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');"
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've been working with C# and .NET for quite some time now, but am currently working on my first ever web application with ASP.NET. It took me quite some time playing around to realize that the Page_Load function was getting called before my button event handler, though, at this point I've got the application working properly around this behavior. However, the issue I'm having is this:
I have a GridView control that is bound to a SortedList in my application. The button click event handler saves data in a form to the database (actually, saves data via a SOAP service), then updates the list that the GridView is bound to in order to reflect the most up-to-date data (again, updates the list from the SOAP service). However, because the page refreshes before my button click event handler fires, the data doesn't actually appear updated on the page. What is the proper way to handle a situation like this? How can I get the data on the page to be refreshed, or at least up-to-date, after the button handler saves data even though the page has already refreshed? I've been struggling with this for quite awhile now, so any code example or links that'll help explain this would be much appreciated.
Thanks in advance!
try inside Page_Load
if (!IsPostBack)
{
//Bind your Grid
}
just write your code in below if condition.
if(!IsPostBack)
{
write your code here in formload.
}
I want to correct Harag's link to the resource regarding the page lifecycle. It can be found here: http://msdn.microsoft.com/en-us/library/ms178472(v=vs.100).aspx.
Though not an answer to the OP's question, I restate it because it's such an important concept to know once you start programming web forms on a more serious basis.
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.
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