This old chestnut again.
My page is constructed as follows; I have a dropdownlist which is databound on first load. When the user selects a value from this, a postback is performed which then databinds a repeater control.
The ItemTemplate of this repeater control contains a placeholder control. In code behind in the ItemDataBound event of the repeater, I am adding two controls dynamically to this placeholder, a hiddenfield and a checkbox.
When the user clicks the save button, I then want to iterate over all those dynamically created hiddenfields and checkboxes and determine their values. However when the user clicks the save button, those controls no longer exist as shown in the page trace.
I know this is a lifecycle issue and the articles I've seen on this suggest using Init methods to dynamically create your controls but I can't because of the way my page works, e.g. the repeater control only appears and binds after a value is chosen from the dropdownlist.
What do I need to do to maintain the dynamic controls through the postback caused by clicking on the save button?
The problem is when you hit the save button probabily you dont re-bind the repeater and the controls you have added at run time withint the ItemDataBound event are not longer available(because they don't exist anymore)
Why don't you add those control at design time using the Eval function the set up the value of the hidden field?
You just don't create them dynamically just on the on selection change of the drop-down set visibility true or false for the repeater that will solve your problem.on post back you have to again create those control as they are Dynamically created.
Related
I've got a Repeater control, bound to a PagedDataSource, which datasource is a list of custom controls I've made. These custom controls contains a couple of text boxes.
I have a save button, and when it is clicked I want to save the data in all the custom controls to a database, no matter which page they are on - but currently I only got access to the custom controls displayed on the current page.
What I've tried to do is to, in the btnSave_Click event, create a new temporary datasource equal to the current one, except its not a PagedDataSource. That way my repeater contains all custom controls - BUT - the changes made in the textbox fields are no longer available. I then tried to add JavaScript onchange events on the textboxes in the custom control, so that a postback would be fired whenever text was changed, and the property in the user control codebehind would be updated. This didnt work either.
Any ideas?
save the changed values on each page index changing event (or prev /next buttons) into your persistance object (List)
http://www.dotnetfunda.com/articles/show/1611/how-to-select-multiple-records-from-multiple-pages-of-the-gridview-and
The reason your non-PagedDataSource is empty is because the changes in your text box exist in the client and not on the server - you'll need to synchronise the values from your controls with the empty slots in your repeater.
The Repeater does not have built-in Pagination (like the GridView or other complex controls) so it does not offer events such as the PageIndexChanging event. I assume therefore, that you have your own Page navigation implementation. You should therefore call the function you have presented within that implemented function.
Try Using a generic List and Skip and Take methods of that
I have a repeater inside UpdatePanel. Inside repeater item I have several text boxes. I also have "Add New" button to dynamically add new items to the repeater. The problem is that every time I press "Add New" all user input is erased. How do I update repeater with preserving user input?
Whenever a Postback occurs, Repeater control loses its state. You might want to perform following quick steps on a Postback.
Convert repeater data to some form of data array (DA) in code-behind.
Add empty element to DA.
Bind DA back to Repeater control.
I have a repeater control that pulls back some data from a database and creates a radiobuttonlist for values related to each row. I don't know how many rows will be coming back, so I don't know how many radiobuttonlists there will be. This repeater is inside of a form, and once I click "Submit" on the form I need to get the values from the radiobuttons generated by the repeater.
Any thoughts on how to do this?
There are a few options.
One is to use a nested Repeater to display the RadioButtons.
The other is to create the controls during the original repeaters. Repeater.ItemDataBound event.
In either case, you need to be very aware of the Page Lifecycle.
You'll want to avoid databinding in the Page_Load event, unless the databinding is being done with an if(!Page.IsPostback) block. If you fail to check for postback, you'll run into issues where the Page_Load calls a DataBind() call that then wipes the values of the repeater before any event handlers can use it.
Alternatively, you can do your binding in Page_Init, which occurs BEFORE the viewstate can be applied, so you won't lose your values.
You can also use USer Controls for the RadioButtons. There's a previous post that covers how to use nexsted user controls within a Repeater here.
i am dynamically adding and removing a different user control from a to a place holders.
The user controls have lot of asp.net controls like cascading dropdowns with autopostback true.
The whole page is in a update panel.
After every postback i again add the control added previously and the which control is added previously is maintained in a view state.
The problem: Only first time the content in the textboxes get cleared after the first postback(caused by changing the dropdown)
Any help is appreciated
You need to make sure that your dynamic controls are being added in the Page_Init event in order for them to retain their data.
I want to make use of "complex" usercontrols with more than one control element within. It's the same control I will reuse in the list, and I have a PlaceHolder control for it already.
I can add the control with LoadControl(path to .ascx) - no problem.
I can through my custom properties get/set access the embedded Labels, too, so I can initialize each control perfectly.
But when adding LinkButtons, I get into trouble/problems.
When I click the button, I do get a "submit" of the page rendering the controls; but the control's own button event does not seem to fire (or at least PageLoad on the parent page seems to fire first?) - I can't figure out where my event goes or where to look for a name/ID or parameter for this button.
How come or what am I doing wrong here?
I've made a "fake button" now by using a label more with a "hardcoded A HREF" with an ID in the URL, but I would like to learn what event I need to catch and where or how to init the button, because I want to be able to use "default ASP.NET" controls for these usercontrols (hopefully without too much patchwork-coding)...
The only reason that events get "lost" is because your controls are not being recreated in such a manner that ASP.Net can associate the event with the control after the postback. It does so through the use of the ID property.
In other words, you're doing one of three things wrong:
1) You're assigning the ID's of your linkbuttons differently during the creating phase in Init after the postback
2) You're creating your linkbuttons dynamically using code, but you're doing it after the Init phase of the page lifecycle, so that your controls do not participate in ViewState.
3) You're re-binding the datasource of the parent control containing the linkbuttons on every postback. Use if (!IsPostBack) to prevent rebinding it every time.
Without seeing your code I can't give anything more specific than that unfortunately.