Web Forms :: Accessing UserControl TextBox Null Reference?
Jan 20, 2011
I have a .ascx file residing in another page which has a button on it. On click I run a select statement that accesses the textbox for a value.
However, it keeps returning a Null Exception Error. I am trying access the textbox and its text through
[Code]....
I also tried -[Code]....
I also tried -[Code]....
But none of them work. Please can someone advise me how I find the textbox and then access its text?I have looked round the forums / google and cant find a way of doing this!
I have a class that derives from System.Web.UI.Page and have set my pages to derive from this custom page class instead of Page. At runtime, the controls are never initialized and throw a NullReferenceException. I've changed some class names and namespaces in the pasted code to protect the innocent. The only thing that I currently override in my PageBase is OnPreLoad and I do call the base.OnPreLoad. I'll eventually add more functionality to this PageBase but for now all that it has is this:
[Code]....
I've tried putting this into a class library (with System.Web referenced) and I've also tried moving the class into the web application and had the same results either way. As another strange twist, I have another class with derives from PageBase called IndexPageBase and it doesn't have this problem:
I have two UserControls on a MasterPage. DataEntryUC contains several TextBoxes and DropDownList. NavSaveUC contains navigation buttons. When the user clicks on a navigation button, I will be saving the data entered into DataEntryUC from the NavSaveUC UserControl.
I have a couple of tables in my DB that contain stored procedure names, control names, control types, SqlDbTypes, etc.... that correlate with DataEntryUC.
How do I reference a text box that is on DataEntryUC from NavSaveUC?
I have been working on the following code from NavSaveUC with no luck.
Dim MyControlName = "txtFirstName" Dim MyControlType = "TextBox" Dim MyStringValue as String Dim tmpTxtControl as TextBox Dim tmpDdlControl as DropDownList Select Case MyControlType Case "TextBox" tmpTxtControl = CType(Page.FindControl(MyControlName, TextBox) MyStringValue = tmpTxtControl.Text Case "DropDownList" tmpDdlControl = CType(Page.FindControl(MyControlName, DropDownList) MyStringValue = tmpDdlControl.SelectedValue End Select
But I am getting null in the string t_Name everytime irrespective of what is the current Text of txt_Name. However I can get the text if I disable the ViewState for the page.
I am using dropdownlist in my view page with some values which will display corresponding ID(primary key of other table) in my database.If i leave my dropdownlist blank and save it in database then its showing null parameter error. Can you explain how to use this reference type to overcome this error
I have a page which holds a custom webcontrol and a usercontrol. I need to reference of webcontrol in usercontrol class. So, I make the declaration of webcontrol as public in page class. But, when I do "this.Page.", I don't see the webcontrol listed in list provided by intellisense. Most probably, I am missing something.
In an asp.net page, how to get a reference of a custom webcontrol from a usercontrol?
I am developing a usercontrol, in this case a toolbar. Some of the buttons on the toolbar will interact with other objects on the page which are not part of the toolbar. (In this case a map) So the toolbar code behind wants to say something like this:
[code]....
My problem is that MyMap does not exist in the design environment of the usercontrol and therefore produces an error when it is referenced. So my question is, How is this typically handled? Can the usercontrol reference another control that does not exist within itself?
I have a UserControl inside the ItemTemplate of my FormView and I need to access it in order to get an event fired off. As the UserControl is inside the template, my event cannot see it!
I am having trouble trying to access a UserControl I created and placed inside the EditTemplate of the ListView. How is it done? I've tried to access it at the ListView's ItemDataBound, ItemEditing and Databound with the following code with no luck:
xamount is receiving this message on the last line. The session is being set in the previous page. Is there a way to resolve the message or should I just use a previous page postback
I'm working on an ASP.NET app.I'm using a UserControl for a year calendar.This UserControl has 12 asp.net calendar controls (for the 12 months of a year)
I'm trying to build a jscript function that can access to one (or more) of the 12 month calendar, but I can't access them.
I'm experimenting with validating forms in the asp.net MVC framework. I'm focusing on server side validation for the time being. I've come across an error that I'm not sure how to rectify. System.NullReferenceException: Object reference not set to an instance of an object. The code that throws the error is:
[AcceptVerbs(HttpVerbs.Post)] public ActionResult Create([Bind(Exclude="ID")] MembersCreate mc ) { mc.Modules = ModuleListDataContext.GetModuleList(); ViewData.Model = mc; //Validation using ModelState // // //line below errors when form field is empty // if ((string)mc.Member.Username.Trim() == "") ModelState.AddModelError("Member.Username", "Username is required."); if (!ModelState.IsValid) return View(); try { // TODO: Add insert logic here return RedirectToAction("Index","Home"); } catch { return View(); } }
When I put spaces in the field it performs exactly as i want, but if I leave the field blank and press submit I get the error. What's the best way to avoid this error and still validate blank form fields?
I've got a master page where I've created two content place holders ('menu content place holder' and 'main body content place holder'). I've placed several controls (drop down lists and a calendar) in one of these content place holders (the 'menu content place holder'). In my content page I've set the 'menu content place holder' to 'Default to Master page content'. In my 'main body content place holder' I've included several controls (table, labels) which depend on the user selected items in the 'menu content place holder'.
After including a reference in all the necessary places- like this:
DropDownList ddlList1 = Master.FindControl("ddlList1") as DropDownList;
I still get the following exception (this exception occurs in my content page):
An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.
Exception Details:System.NullReferenceException: Object reference not set to an instance of an object.
let me see if I can explain this clearly. I have a gridview control and I am trying to use the Edit function. In my gridview, there are numerous rows. I pick one to change and click Edit. I then see the boss name in my gridview and click "Change". When I click Change, I'm expecting two fields to appear, one is a label, the other is a DropDownList. I get this error when I click:
System.NullReferenceException was unhandled by user code Message=Object reference not set to an instance of an object. Source=App_Web_lzmklgbg StackTrace: at Training_TRManageOrg.LinkButton1_Click(Object sender, EventArgs e) in d:projectsediting.aspx.cs:line 108 at System.Web.UI.WebControls.LinkButton.OnClick(EventArgs e) at System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.LinkButton.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) InnerException:
I am stuck into a problem, i have a user control ProductListing.ascx that contains ListView binded to an object datasource, SelectMethod and SelectCountmethod are provided as well. Everything works fine but the problem started when i add another user control declarativlly Filter.ascx in the productListing.ascx. I want to assign value to a public property MaxPrice in Filter.ascx. I am trying to set this property in the SelectMethod of ObjectDataSource. Usercontrol "Filter.ascx" throws null reference exception when i try to set its MaxPrice Property.
I tried to acced the usercontrol in Databind method of ListView , it is accessible here but viewstate is empty at this point, i saved the value in viewstate in SelectMethod of objectDatasource but i cant access viewstate in ListView Databind. Its empty. Its a simple code and no rewriting to viewstate elsewhere.
Important: My Codebehind files are in a seperate project and .ascx files in seperate project
I developed a page in VWD 2008 and it works perfectly locally, but when I deployed it on the server every Page.FindControl() call is causing the NullReference Exception "Object reference not set to an instance of an object. " Can anyone help me out? Code is below
