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.
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');"
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 an ASP.Net page with two ListBox components, rendered in the browser as <select> lists. I'm using jQuery to move elements from one list to another by manipulating the DOM. I then select all elements with the mouse and postback the form. That way, all the list elements are posted with the form.
When I submit the form, in my button_save() event handler, the Request.Form[<<listbox ID>>] values are correct. However the ListBox controls themselves, specifically their Items collections, do not reflect my changes.
I've also used Fiddler to modify the select items and submit the form. Same as above, the ListBox values are no different, though the Request.Form values are. Would anyone know what's going on or what incorrect assumptions I'm making?
I believe the problem is that the server constructs a ListBox object that is unaware of changes made to the select box on the client side. That is to say, it uses the ASP.NET markup to construct the list of items, rather than the information submitted from the request.
I'm not aware of any workaround to this, other than accessing the Request.Form values directly.
I believe the root issue is: the ListBox's options are stored in the page's viewstate. When you use client-side javascript / jquery to modify the list's contents, those changes are not reflected in the viewstate. Thus, when you postback, ASP.NET uses the viewstate to build the lists for your codebehind, and your client-side changes are lost.
One way to resolve this would be to manipulate the lists' content via postback, instead of client-side (javascript/jquery). By doing it that way, all changes to the listboxes are incorporated into the viewstate, and thus will remain consistent for each postback.
I am a big fan of jquery (much moreso than postbacks or MS-Ajax/partial-postbacks), so I completely understand that this approach may not be very appealing. Unfortunately, it's the only one I can think of right now. Maybe other stackoverflow'ers will have better alternatives.
Larry, in case you haven't found a solution, here is what I would do.
As other fellows stated, since you are changing DOM client-side, the changes are not reflected to ViewState and therefore you cannot access new values from code-behind.
As a solution, you can create a hidden value and set its value to a serialized form of the lists (combined value/text pairs) everytime you change a list with jQuery. Then you can access the hidden value from code behind and finally deserialize it to get all changes. The method is pretty straightforward actually.
My ASP.NET WebForm has a place holder on it and user controls are dynamically added to it. The controls mostly have textboxes. Sometimes there are two user controls, sometimes there are ten. Everything is working as expected. My question is about how to implement a new feature.
My customer has a new request to copy data from the first control to another control checking a checkbox associated with the additional control in question.
At first, this sounded easy... Add a checkbox to the placeholder for each user control and then write some JavaScript to copy the data from the first control to the additional control. Then I realized that by those textboxes being in a user control, I don't really have access to modify the HTML inputs directly.
Next I started thinking about adding checkboxes that will automatically post back, but how do I go about dynamically adding a checkbox to a placeholder, and then come up with a way to add event handler to the checkbox and pass in the information necessary to loop through the controls and copy the values. This approach seems way too complicated with too much overhead to accomplish my goal.
Any suggestions?
You mentioned that since the checkboxes are in a user control, you don't have access to them.
Could you expose the ClientIDs using a property of the user control and then work with them in javascript? Something like this:
user_control {
int checkboxId { get { return checkbox.ClientId; } }
}
If you have more code that would be helpful...
This is probably too late to help you, but just so another answer is out there...
Including the checkbox as a part of the user control simplifies the issue considerably.
I had a similar situation, with maybe 10-15 UI controls in a user control, with a checkbox associated with the first one which, when checked, meant that I should copy the info from the first user control to all of the others.
Since it was all built in the codebehind, I simply exposed a boolean property of the user control named ShowCheckBox, which toggled the visibility of the checkbox. I set this to true in the first one, and false in all of the others. Thus, I knew that the event could only be raised by a click of the first user control's checkbox. Then, in the event handler for the checkbox, I handled the copying from the first user control to all of the others. (By the way, be sure to set AutoPostBack=true on that checkbox or you'll wonder why the event isn't firing.)
Javascript would definitely provide a better user experience, but this worked for me and didn't require me to figure out how to get the ClientId values into the javascript. (Although that's exactly what I need to do now, which is how I stumbled upon this question. :-) )
I have a requirement where I ask user for confirmation and also display messages.
The programmers used for this were from Windows forms background. Hence have used the MsgBox in every nook and corner. Even in business logic part they have used the Messageboxes which requires Yes/No style confirmation from user.
When we tested the site from the remote machine we found that it gives error of using DefaultDesktopOnly/ServiceNotification. But when tested we found that this is totally different from what we were looking for.
Now my requirement is a confirmation box is shown from the code like Delete record" yes no and based on the reply we take the action.
This is to be done using updatepanel.
As you use this code in several places, I suggest you make a custom control, that takes your message and displays and Update panel with message and yes/no buttons.
Internally set some value for yes, no, cancel... so that you get something just like MessageBox.
Update panel or not, you'll have to attach some javascript that would call confirm() javascript function. Based on it's result you cancel javascript default link/button behaviour...
This will give you something to scratch your head for a start:
http://www.dotnetfunda.com/tutorials/ajax/updatepanel.aspx
That's not really a question, but a requirement.
Anyway ... MessageBox is a Windows function, it is not an HTML or browser function. Now you can mimic it in one of two ways, via a javascript confirm function or via Yes/No buttons and the appropriate event.
Given that your requirements are for something that works in an update panel I'd guess that wiring up javascript events manually for this isn't going to be something you are comfortable with, so I'd suggest an asp:Panel inside the UpdatePanel which has yes and no buttons, with server side events bound to them. In the UpdatePanel logic show this when you want confirmation and hide everything else, the act accordingly.
If you want to do server-side confirms, you'll get into more complicated code generation. First of all, you'll have two views. The first one has a link/button delete but will actually be just a postback to the second view that will display confirmation form with yes/no. In this form, your yes button will actually be your delete action...
But I'd still chose a hybrid (especially if this is a grid we're talking about) of javascript and serverside (since alert() and confirm() are evil from user experience perspective):
you have a linkbutton delete
when user clicks on it, you replace this control with a div, that displays two linkbuttons yes/no
send a postback with one of the two
Addendum
No linkbutton could be just dummy, to hide this confirmation and display delete again - so it means there won't be any server round trip
you could even create a usercontrol that mimics this sophisticated delete link behaviour to make it reusable application wide.