Web Forms :: Getting Values From A Server Control Before Postback?
Aug 19, 2010
I created a ASP.Net page with dynamic controls. These controls are added by the user. In the Page_Load event a table is created with few controls.
When these dynamic controls do a postback, I can't get the values of these controls, because in my HTML code they are not available.
I only get the id of the control which triggers the postback. But I can't find it with the command FindControl. All other controls, which a are not added dynamicly are searchable.
I've created loads of user controls, but this is my first time dealing with extending a server control. The problem I'm getting is that the base control's data is not being persisted across postbacks in a Master/Content page.I'm actually trying to get this working using a Telerik control (for my sins), but the same issue happens with a standard Web TextBox control. Code:
[Code]....
Now, I've copied the way I handle the control state as I do it with user controls (ControlState), and it isn't working. Can someone point me in the right direction please? All the examples I find refer to creating user controls, not extending existing controls. Specifically why nothing is being persisted on post back.
I'm constructing a User Control that will have one Property called "ContractIdx". Here's how I've constructed this Property:
public int ContractIdx { get { return Convert.ToInt32(this.Attributes["ContractIdx"]); } set { this.Attributes["ContractIdx"] = value.ToString(); } }
I'm initially loading the User Control by passing a parameter to it and setting ContractIdx accordingly. That all works fine.
Upon Postback though I'm loading the User Control without any parameters and then setting its ID property to what it was before the Postback. My understanding was that if I did this then ViewState would properly restore everything. Yet apparently this is not the case with the "ContractIdx" attribute.
Where am I mistaken in my understanding? How should I change things to get this mechanism to work?
I created a server control that has some javascript. Everything was working fine until I added it to a page that has localization implemented. The implementation is done within the Global. It sets the Thread.CurrentThread.CurrentCulture and CurrentUICulture based on a setting saved in session. When these values are getting set, the control throws the following error:
Microsoft JScript runtime error: Sys.InvalidOperationException: <file.js> Type has already been registered. The type may be defined multiple times or the script file that defines it may have already been loaded. A possible cause is a change of settings during a partial update.
I have the control contained within an update panel on the page, the control also contains an update panel containing all elements withing the control.
I populate web form with dynamic list of exams from database. I want user to enter examination marks for each exam. There is list of exam titles and textbox near each title.I create list with repeater control (ViewState is disabled)
class Exam { public int Id { get; set;} public string Title { get; set;} } ... // this list is retrieved from database actually Exam[] Exams = new Exam[] { new Exam { Id = 1, Title = "Math"}, new Exam { Id = 2, Title = "History"} [code]...
How Can I retrieve values from TextBox before RowUpdating function is fired? I have GridView with update panel which is sorted by two dropdownlists and I need autopostabacks to filter and bind gridview. Now I want to update row in my gridview but I can't get values from controls I'm getting old values from database. Do you the way that I can use values from controls before updating the row?
I'm getting some wierd behaviour with my User control. I've created User control & it has BUTTON which checks the validity of the number entered in the textbox of that user control. I have written Button Clik event handler in the USer Control code behind which checks the database table and tells valid or not. So far so good. In my application i dynamically add User controls. I make sure that I add them Page_Load so that for every postback UCs are visible. I'm ussing Session to save my UserControls. The problem starts at some point when i click the Validate button in the User Control all my user controls dissappear & after some postbacks all my controls appear. I don't know why this is happening. I have included my code for reference.
I have some problems with trying to read values on a postback. The fields, textboxes and dynamiclly created fields doesn't keep their values or I'm doing something wrong when trying to read the values. I get an error message:
System.NullReferenceException was unhandled by user code Message="Object reference not set to an instance of an object." Source="App_Web_m-6qot6q" StackTrace: at Sikt.RäknaVärden() in C:Visual Studio 2005WebSitesKalibreringscertificatSikt.aspx.vb:line 688 at Sikt.Button1_Click(Object sender, EventArgs e) in C:Visual Studio 2005WebSitesKalibreringscertificatSikt.aspx.vb:line 892 at System.Web.UI.WebControls.Button.OnClick(EventArgs e) at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
Also, I get some other errors, such as "Name 'DropDownList1' is not declared" and "Name 'Label1' is not declared" I'm used to classic ASP and this is my first .net 2.0 (vb) application. I'm including some of the code (should be all relevant code)
I just uploaded an asp.net webforms site I've been working on to my ISP's servers. I have a simple page that allows users to enter schedule data. The problem is that when the user clicks the Add button and I try to process the values they've entered in the textboxes and dropdownlist in the click event handler, all the values are blank. For example, there's a DropDownList called uxStartTime on the page and after postback uxStartTime.SelectedValue is blank. However, the Response.Form[uxStartTime.UniqueID] has the proper value. I have EnableViewState="true" in the aspx page. This all works fine on my local machine, just not on the server. Can anyone tell me what's going on? I can use the Respons.Form syntax, but it's a little more verbose and prone to typos.
I am using string builder class to store the dropdown selected values .. I am doing this on the selected index change event .. The problem is the previous value does not retain ..
I would rather specify fields in my code behind than embedding them in the .aspx page.
I also have a subtotal label control in my repeater that I would like to populate its text property by mutiplying two of the database values e.g productprice * unitprice shown in my repeater.
I need to do this in code behind, looping through the repeater. Any idea of how I can do this in C#?
I wanted to know if we can pass values from Parent page (in this case from Default.aspx page) to the user control and maintain those values on subsequent "Add/Load" of user control.
So in short, if I click the "Add" button it loads my "webusercontrol" and also I am able to pass my default.aspx dropdownlist value to this dynamically loaded user control and assign it to a "Label or Textbox" which resides in my "webusercontrol", now the problem is that the value doesn't persists! What I meant is , when I click "Add" button again the "webusercontrol" gets loaded again perfectly but now all my "Label's" in webusercontrol has the new selected value from the default.aspx dropdownlist.
So say for instance I have a Dropdownlist in Default.aspx page with Values "Apple, BlackBerry, Nokia" and initial value to be passed is "Apple", I click the "Add" button, now my "Label" inside webusercontrol has the value "Apple", perfect! Next when I click "Add" button again and select a different value to be passed this time say "BlackBerry" now I have 2 webusercontrol loaded on the page, so that means I have 2 "Labels" with different ID's, but now my first Label initially had the value "Apple" because that's what I had passed and now when I passed the value "Blackberry" both the labels of my webusercontrol has the value "BlackBerry" instead of one being "Apple" and another "BlackBerry"
Is there a way to resolve this issue? may be Dictionary List?
I am having an aspnet panel in my aspx file.There is an ultraweb tab placed inside this.also I am having a button outside this panel.Within the tab I have a textbox whose readonly property is
set to "true".Whenever I click the button a javascript function is called .On clicking 'OK' in the popup ,the textbox values are lost.Is there a way to retain these values?
i want to hold data at runtimeEx-I have a 3 Services A,B,C and in A,B,C contain services list,then if user select A service and 3 services in a A Listagain user select B service and 2 services in a B Listand again user Select C Service and select 1 services in a C listSo How i can hold data A,B,C services ID'S value with respect to services listID'S value at runtime.
I have a custom server control (composite control having dynamically created dropdown boxes and textboxes). I have enabled AJAX in order to avoid page reload.The server control is used inside the ASP.NET webcontrol having few buttons which controls the visibility of the server control. Now I enter values in the dropdown box and texboxes and click on any other button. After this postback the last entered values are gone! The control is not remembering the values. How can I retain the values after post back?
I need a way to create unique values for a property in my custom server control..
In this case I will have the poroperty called "Name" and I neeed the value of Name to be unique for each "instance" of the control...
So for instance if I have a page with more then one instance of the control, I dont want the value of the Name property for these instances to be allowed to be the same..
...to put it kind of simple, if I dont remember this incorrect, I want it to be sort of like the ID property..but with another name then ID.
Im binding the gridview in page load.After i click the link button in the gridview it displays another gridview.I have a checkbox in that gridview.I check some of the checkboxes.while i click the save button i want to get that checkbox state whether its checked or not.Bt for me its showing no records in the grid.How do i persist my data and get the checbox's state.
I know that on a postback all controls are rerendered.My problem is that I have an page who holds panels who holds web user controls who holds itself x time an panel with an web user control.I have an action that takes an postback and it resets all the design of those web user controls, but not the controls of the main page.What can I do to save the current state of my page ? The current panel that is visible etc.I tried a simple update panel without success by setting UpdateMode to conditional and ChildrenAsTriggers to false.
I have a form with 2 sections. The first one contains some radio buttons. The second one contains a checkboxlist. When we change the selected radio button then it modifies the elements in the checkboxlist. For this I setted the radio buttons with autopostback, and in the code behind (in OnLoad) I populate the CheckBoxList depending on the selected radio button.
This work fine.
The problem is that I also have a button at the end of my form which post the data of my form in another page (with PostBackUrl). Then in that page I would like to retrieve the values of the checked checkbox. But I can't find how to do that. In the Request.Form I don't see anything.
I searched on the web but I didn't found really a solution.
I have a user control which has some properties configured on it. I need to access (actually, only read) the values of those properties on the client. I have done it like this.
Code behind:
[Code]....
ASPX:
[Code]....
That works but, at the back of my mind, I'm sure I've seen a neater way of doing it, although I suspect that may have been on an Extender not a User Control. Pointers on that welcome.
Also, related to that, the User Control itself has an Id which becomes part of the name of all visual objects included within it. However, the User Control is not a DOM element in its own right (because it has no visible rendering) which [I think] means that I have to attach properties to one of the visible elements within it, and not to the control itself?
I had successfully created a functionality where I can dynamically add rows and columns to a asp table by creating/re-creating controls on every page load.
I have 2 buttons - Add rows and Add columns that, basically according to a asp.,net page life cycle, occur in the following order and work perfectly fine.
Page load is fired and controls along with their viewstate are recreated. In Add row button click event - I just create a new table row and add controls to each cell dynamically.
Same thing with Add column, Delete Row and Delete Column button click events.
However, now I added a Dropdown which when its index is changed needs to retrieve values from the database and create controls based on those values and then also bind the Db values.
But it doesn't work correctly since the asp.net page cycle cannot capture the dropdown's selected value in page_load as the page_load fired first and then the selectedindexchanged event is fired later, the controls are not created.
I don't know how to handle this scenario and incorporate it into my existing code.
