I've been getting this exception in my code and wondered if anyone could help me out.
I have a Repeater Control bound to an ObjectDataSource, and the itemtemplate for the repeater contains a User Control (ASCX). This user control in turn contains several other controls, mainly a GridView that is associated with an ObjectDataSource.
On initial use of the controls in this setup, everything works great - data displays properly. However, when I change a filter option (dropdowns outside of the repeater), and then rebind the Repeater, I get the exception:
The ObjectDataSource control 'expDataSource' does not have a naming container. Ensure that the control is added to the page before calling DataBind."
at System.Web.UI.WebControls.DataBoundControlHelper.FindControl(Control control, String controlID)
...
...
at System.Web.UI.WebControls.ObjectDataSource.LoadCompleteEventHandler(Object sender, EventArgs e)
I'm not sure what the problem is - I've read in a few places that moving the datasource outside of the ASCX control might help - this does nothing. The objectdatasource appears to be properly structured, and as I said, it works the first time (only).
I noticed in the stack trace for the exception that this is occurring when ASP.NET is calling FindControl() after LoadComplete() occurs. If I step through my code, it appears as though all my code is finished executing before this happens, so it's all "system" code.
Why would ASP.NET not be able to find this datasource control in the LoadComplete Handler?
Thanks!
Other Notes:
This error occurs every other time. So the first time the data loads properly, then on second refresh fails with this error. Clicking "Load" again, it works (on the third time).
On the times that it fails, it looks like "Page_Load" is being called twice in the ASCX control. So the patterns are:
Working Pattern:
Page_Load on Parent Page
Page_Load on ASCX
Data Loads fine
Failing Pattern:
Page_Load on Parent Page
Page_Load on ASCX
Page_Load on ASCX
Exception
This is all happening from a call to "Repeater.DataBind()", but it behaves differently depending on if it has already been bound or not (evidently).
More Notes:
Real strange behavior. I removed the list of SelectParameters from the bottom of the ObjectDataSource, and all of a sudden, the page does not reject the ObjectDataSource as not having a NamingContainer. Of course, without these parameters, Databinding won't actually work...I can add them in the code, but why would it matter?
Found a strange solution, that I'll post and we can discuss to maybe figure out why this fixed it.
On my page, I had the following structure (paraphrasing the tags somewhat):
Page
DropDownFilter
Repeater
UserControl X
ObjectDataSource
ControlParameters Referencing DropDownFilter
End ObjectDataSource
End UserControl X
End Repeater
End Page
So as you can see, within the Repeater ItemTemplate was the user control, which in turn had the "guilty" ObjectDataSource with ControlParameters. These control parameters had the name of the DropDownList filter on the parent page referenced (so basically, if this control was added to any other page, it would of course fail if it couldn't find a control with the proper name).
So when I went through and changed all the ControlParameters to Parameters (removed the reference to that DropDownList control), now I no longer get the error.
All I can assume is that the fact that this datasource referenced a control on the parent page meant that it was having trouble getting added back to the page's control set on a DataBind(). You would have thought it would fail the first time if it was going to fail at all, so that's still a mystery.
Any thoughts?
This is an exceptional error in ASP.NET DataControls. I had similar problem and lost few months behind this eccentric error, but finally got the solution. The reason is; To display items in ItemTemplate, we should use a server control in the LayoutTemplate to act as the placeholder for the ItemTemplate. For example, we could use a Table/Div control with an ID Property in Layout Template. At run time, this placeholder control will be replaced with the contents of the ItemTemplate and "naming container error" will be disappeared.
Finally, if you are having an objectDataSource in ItemTemplate, make sure that you added somthing(like table/Div) with "Id" property in Layout Template.
Thanks,
Sunil.
Ray hit the nail on the head. You are definitely missing an "if(!IsPostBack)" somewhere. How are you adding the user control to the repeater? Is it dynamic? You say it's in the ItemTemplate, so probably not... But multiple calls to Page_Load imply multiple copies of the control.
Use both DataBind. Example:
SqlDataSource1.DataBind();
ListView1.DataBind();
Related
Allright so I have a slight issue when I want to load some basic usercontrols which contain an UpdatePanel inside to another page which is an usercontrol.
The set up:
Whenever an user clicks on a button a pop-up shows up containing some basic info on a certain person and a tab which contains the companies he worked for. The amount of companies he/she works for can range from 1 to 4~, so I do a query then for each company I get I add a view to a multiview, this view contains multiple simple user controls (Textfields inside an updatepanel). Now whenever I go to the page I get this error:
Cannot unregister UpdatePanel with ID 'UpdatePanel2' since it was not registered with the ScriptManager. This might occur if the UpdatePanel was removed from the control tree and later added again, which is not supported. Parameter name: updatePanel
Now I know this is a common error caused by generating UpdatePanels dynamically which aren't registered with the ScriptMaster. I can't add a PreInit event handler to the page which adds the UserControls with the UpdatePanels since it's an UserControl itself.
My question is:
How can I get rid of this nasty error in a not so nasty way e.g. not a hardcoded sub routine which adds the UpdatePanel to the scriptmaster
You could define the functionality you want to add inside your user controls. I have done the same in the past, adding the following, inside of my user control.
override protected void OnInit(EventArgs e) {
// your code here
}
Add a ScriptManager on your MasterPage before the UpdatePanel. And your updatePanel is a bit confusing so might change it as well. :)
The scenario:
I have some JSON data which I'm using to load stored-data into fields on my form. One of these fields is a DropDownList. The DropDownList happens to be in a child, of a child ASCX control, which I'm accessing from a parent ASPX page. When this DropDownList has its SelectedIndexChanged, it makes other fields visible on the form.
I'm using one of my functions to find this control, which is working successfully, but when setting the SelectedValue of my DropDownList control, the SelectedIndexChanged event is not firing. Meaning some fields aren't loading, resulting in some JSON data not being loaded and lost.
I have seen a suggestion of simply calling ddl_SelectedIndexChange(sender, args) function, but the page I'm calling dynamically loads hundreds of child controls depending on the current request, so was wondering if there is a way of invoking the SelectedIndexChanged event (if it exists) for a control, without having to search and manually call the ddl_SelectedIndexChanged() function. Is it possible?
DirectCast(WebUtils.ControlFinder(upMain, f.fieldClientID), DropDownList).SelectedValue = f.fieldData.ToUpper()
I hope it makes sense. Sorry if I haven't made this clear enough.
I ended up using Reflection to Invoke the properties event that I required, worked a treat.
I have a FormView in an ASP.NET UserControl. The EditItemTemplate contains some controls, and I'd like to run some code server-side whenever they are created, to set some values based on some conditions.
It appears that the Control.Load and PreRender events are unsuitable for this, since the control can sometimes be rendered without any child controls (not sure why that happens). Specifically, if I look at FormView.ChildControlsCreated in the debugger, I always see True, but when I try to FindControl by name, sometimes it's there and sometimes it isn't.
When should I execute my code that requires access to the inner controls?
This happens because the FormViewMode is sometimes different. There is no template for ReadOnlyMode, so whenever the form is in that mode, FindControl doesn't find anything.
Using ASP.NET 4.0 WebForms.
I have a repeater with checkboxes in it. The repeater and checkboxes have viewstate enabled. There's a button which causes a callback postback. These elements reside in a callbackpanel (similar to MS's UpdatePanel but doesn't use viewstate). The repeater is bound to a datatable during initial load and repeater shows the checkboxes. Fine so far.
During the postback (a callback), I noticed that the repeater's items' count is 0 in the page_load. Therefore I can't get any checkbox values. I can see the key/checked value entries of the checkboxes in Request.Form collection.
I think I am missing something obvious but where in the life cycle can I read the repeater's items?
Or should I get them from Request.Form?
1) Try wiring up to LoadComplete. All child controls are loaded recursively, so sometimes not everything you expect to be there will be present during the Load event.
2) Make sure your repeater is initialized during or prior to Init event. If you have some code that runs to populate it, then this must be executed in Init. During the page's lifecycle, ASP.NET tries to take the posted values and apply them to the controls. If the controls are not created soon enough during the lifecycle, then they won't exist during that step to accept the posted values. This is one of the more frustrating things with dynamic pages in ASP.NET, as you have to ensure the page is reconstructed during the postback in init. So even when you see the data in the post, ASP.NET will ignore it if the controls aren't found in its collection of controls. Also, there is some magic that happens with control IDs that it uses to map the posted values into the controls. I don't remember the details of that though because it has been several weeks since I had to delve into the harry details.
Also, make sure you aren't doing something like using if(!IsPostBack) to initialize your repeater or other controls/data. Even if it's a postback, you still need the controls to exist so they can accept the posted values.
I have not used a callbackpanel though, so I am unsure of how this will muddy the waters.
I solved my problem by overriding the DataBind method on the control which contains the repeater. That prevents DataBinds on parent controls from trickling down and binding data to the repeater when it isn't ready for that. My problem was that a parent control/page performed a DataBind which trickled down to the sub-controls, including the repepater, causing it to get cleared. So you don't have to do a DataBind directly on the repeater on every postback like #AaronLS suggests:
Also, make sure you aren't doing something like using if(!IsPostBack)
to initialize your repeater or other controls/data. Even if it's a
postback, you still need the controls to exist so they can accept the
posted values.
All my RepeaterItems were stay present through postbacks even though I only databind once.
In my case, performing a DataBind on the repeater for every postback caused the form values to be reset.
Can someone explain exactly how/when an ObjectDataSource fires? I have an ASP.NET page, with a GridView, which is referencing an ODS. I put a breakpoint in the method the ODS is using, and noticed it was firing twice.
I looked into the code and the answer seemed obvious at first. I had
Page_Load()
{
if(!Page.IsPostBack)
{
MethodA();
MethodB();
}
}
where MethodA and MethodB were both eventually calling gv.DataBind(). This made sense because I assume that each call to GridView.DataBind() would result in asking the ODS for data, and therefore running my data access method.
The weird thing is that when comment out the call to MethodA, it still fires twice. Checking the call stack shows the method being run first as a result of MethodB, and then again, with no trail except [External Code]. This mystery load does not happen when I let MethodA and MethodB both execute.
Any idea what's going on here? Any idea what other code I might have that is asking the ODS for data? I'm starting to think all these 'no code' data controls are more obfuscation and BS than they're worth.
I've experienced this problem when we were hiding/showing gridview column dynamically in code.
Here is a page that talks about some issues that might cause multiple Selects
http://forums.asp.net/t/1161164.aspx
Multiple calls to a gridview's databind method can occur implicitly if you're changing the visibility, i.e., showing and/or hiding, the columns of a gridview tied to an object data source.
In this scenario, try encapsulating the show/hide gridview column code in the Page_LoadComplete event handler.
The Page_LoadComplete event handler is in a prime position in the page lifecycle to prevent multiple databind calls and still be effective as it is invoked after control change events (e.g., button click, drop down selected index changed, etc.) yet before the gridview databinding events.
"when comment out the call to MethodA, it still fires twice". So it will likely be Page_Load called twice. Probably you have AutoEventWireup="true" and also registering event in code http://www.aspdeveloper.net/tiki-index.php?page=ASPFaqEventsDoubleFire
If you set the datasource of the gridview with something like
gv.DataSourceID=dsObjDataSource;
then the grid view calls gv.DataBind() on its own.
I had the same problem - the problem was that I was hiding/showing a column after, or during, databinding. Moving the hide/show code before the databinding stopped the binding from happening twice, which I suspect is the same effect as moving it to the Page_Load. In my case the databind was happening in response to a dropdown listbox change - doing the column add/remove before the DataBind() call fixed the twofer problem for me.
I was getting the same result with DataBinding occuring twice using asp:DataList and asp:ObjectDataSource.
It turned out to be because I was using a UserControl in the select parameters:
<asp:ControlParameter Name="GroupID" Type="Int32" DefaultValue="-1"
ControlID="UserControl1" PropertyName="SelectedGroupID" />
I am getting weary of UserControls. I can see how they might be productivity enhancement for 5th graders but they are a complete waste of time at a higher level.