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');"
Related
Please excuse me for a probably low quality of this question, since I'm not a web dev, so I possibly don't now some obvious things and don't know what to Google for. I think problem must have some simple solution, but I'm struggling with it for two days now, so I feel myself pretty stupid :-).
I have a custom control which is a set of checkboxes which are added dynamically based on a property which is set in OnLoad event of a page. I have two such controls on a page and second control items should be based on items selected in first control.
The problem is, I can't figure out, how to catch on autopostback which boxes were selected in first control before second contol is constructed to pass this data to it?
Take a look at this.
http://forums.asp.net/t/1440174.aspx
Since your building them dynamically, they are not as easy to find as webforms would like to be, if you added them to the page and wired up events and such.
Your going to look at the Request.Forms list, and search thru it for any controls you want.
I believe checkboxes are like radio buttons, they only return if they are checked, which is good, cause you want to know which ones were checked.
I've used same solution as in the accepted answer for this question: Dynamically Change User Control in ASP.Net , just need to assign an unique id for each dynamically created CheckBox in custom control. Not as clean solution as I want but at least it works.
You can save the data in the ViewState, QueryString or as Session before moving to the next page and you can do modifications based on it.
I have two controls of interest on a page: a DropDownList and a Button. If the user presses the button, he gets a popup form which, when completed, causes the base page to completely reload, losing the value in the DropDownList. To clarify, it's a refresh, not a postback. I cannot change it to make it a postback. What is the most straightforward way of persisting the selected value in the DropDownList across this page refresh? I cannot avoid the page refresh, because the data entered in the popup is reflected elsewhere on the base page.
Update
I've cobbled together a tenative solution that I'm not terribly happy with: when the user clicks the button, I use javascript to get the current value of the dropdown and pass that with the querystring to the popup being loaded. When the user clicks "Save" on the popup, which causes the data to be saved then the base page to be reloaded, I first store the querystring value into a Session variable. The base page, on loading, looks at said Session variable. If a value is present, it sets the value of the dropdown accordingly and deletes the Session variable.
Although somewhat kludgy, it's the best I can come up with. I know that my Gracious Benefactors dislike using Session variables, but given the page reload, I cannot come up with an alternative. Also, since the Session variable is short-lived, being created shortly before a page is closed then being deleted shortly after the succeeding page is opened, I'm hoping this will be acceptable.
Contrasting opinions, refutating my solution or reasoning, are enthusiastically welcome.
Conclusion
Ultimately, after I described the solution to my Gracious Benefactors, we agreed upon an alternate approach: if a selection is made in the DropDownList, it must be saved before opening the popup. This avoids the whole ViewState problem altogether.
For updated question:
The solution you are trying sounds like it should work. It's not the sort of thing you want to use SessionState for but there are requirements here that make the situation out of the ordinary.
Depending on how you are getting the base page to reload you may be able to add a query string to that which would save you from putting hte value in the SessionState. But I imagine you have probably considered that.
But basically, as Postback values and viewstate are out of the question, SessionState and query strings are you only real option. Oh, unless you are allowed to use HTML5 local storage? (probably not)
From before question update:
If the aspnetForm is being posted back the the value should be persisted automatically by means of the postback values. So the first thing to know is whther your form is going through a postback or if you are refreshing the page in some other way.
If you can't postback the main form then as rockinthesixstring said an Ajax post might be what you need.
Also, if you are doing anything fancy with binding the datasource to the DropDownList or trying to persist the selectedValue yourself then check and re-think that.
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
hello friends i have a check box list which contains all the courses kept in the data base(on page load) now i want that on some event of check box list all branches corresponding to each checked box of course check box list should be list in another check box list(that is the business logic i will do my own) but the problem is that i am not finding any event where i can send all selected check box list value and can generate appropriate result, if any alternate control or solution you can suggest then please suggest me this.
Set the AutoPostBack property to true and in the SelectedIndexChanged event you can loop over the elements that are selected and then bind your second control depending on that.
Another option would be to go for an ajax solution. For this I suggest you take a look at the change event in jQuery to bind to your checkboxlist and use the ajax stack to retrieve the extra information as html and plug that into a span as innerHtml.
I think you need to clarify where your logic sits, and where the information required for that logic to work sits - in order to even know whether you're dealing with a client-side or a server-side technology question
There's two basic possibilities:
Either all required inforamtion is already in the loaded page. In that case, this is basically a javascript problem. I'd dive a bit into jQuery here which has excellent capabilities of finding elements based on properties, and manipulating them
Alternatively, some of your logic and/or data remains on the server. In that case, you can
go with the AutoPostBack property XIII mentioned, resulting, as you correctly assume, in a reload after every click.
Have the user click all the checkboxes they like, and then have them click on a "do something now" button which performs a single postback
Transmit the information about the checkbox click to the server via javascript, get a response, and select other boxes accordingly. Again, XIII already mentioned that by "ajax solution".
So I'm just trying to elaborate on what different approaches do for you, and what questions you need to answer yourself before you can proceed to a concrete technical solution.
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.