I have a dropdown list which retrieves data from a datasource. I must to update the dropdown when I add new data to the database through another page. I've not found documentation for this kind of updating, that would be like the requery method on DAO databases for VB6.
it really depends on how you have designed your page, you could refresh the page with a refresh button or with the refresh of the browser or even via JavaScript which reloads your page every x minutes, then you will query again everything because the page will have a full life cycle again.
if you want to do more sophisticated things you can of course use Ajax ( PageMethods or UpdatePanel approaches ) to have a partial render.
Using the databind method for the dropdown will force the update of the control. But the combo will be updated only when the page is reloaded. Maybe the best way should be using Ajax...
Related
I am adding RadDock control and adding its Item Command events which require to be added in Pag_Init. And adding user controls to RadDock.
My problem is that when I have some post back for a specific control page_Init calls which reloads the controls and every control is re-binded every time. I want to avoid control creation every time. And want the specific control's post back should happen.
If I apply (!IsPostBack) condition in Page_Init then controls are not loaded and page gets empty.
I am stuck.
Any best practice or work around is acceptable.
Thanks in advance.
I don't know the specifics of Telerik's tools, but if they work like regular ASP.NET dynamic controls, you have to add the controls to the control tree on every page load. Populating the controls with data is distinct from adding them to the control tree. If the controls are added correctly so that they are placed in the same way in the control tree as on the previous page visit, and implement ViewState correctly (if needed) the runtime will populate them with data from the posted data and ViewState when a postback occurs.
I added IFrame to RadDock and then gave user control source to IFrame. Now it is working fine, Only the specific control's post back occurs.
Any way, Thanks Jonas
This is a little difficult to explain so please bear with me.
I have a procedure that is generating some radio buttons and assigning a CheckedChanged postback event based on the level being passed through (up to 4 levels). When the first level is checked (radio button selected) the postback event rb_CheckChanged00() is called and a check is done to see if this item has any children, if it does, it will create more radio buttons and assign rb_CheckChanged01 to the CheckChanged event for these - This part is working fine.
The issue I have is when I select the second Radio Button that has been created (the child), it doesn't seem to go to the post back event at all. The page is posting back when I click on it but everything resets because it won't go into rb_CheckChanged01.
I know this info is quite vague but I am hoping someone has an idea on how the post back event works and if I am somehow using it incorrectly.
Using: ASP.NET 2.0, IIS7
Thanks.
Most of the time when the dynamically created control's events are not fired, it's because the controls are 'reset' upon postback.
To make sure the same controls get created each and every time make sure that the control's IDs are set to the same values each and every time, before the ViewState is loaded. This way, when the control is added to the control collection of the page, once the ViewState is loaded, it'll persist it's properties. (just to describe what happens, in a nutshell)
One of the best articles I've read on this topic is this one. Make sure you read it, to fully understand what's happening in the background.
Looks like the child RBs are cleaned before they are able to trigger the event. From my personal experience, it's best to keep track of those dynamically generated objects, and regenerate them in every postback. The events will start to trigger :)
Your controls and events are not registered in the ViewState because dynamic controls need to be loaded in the Page_Init. Because they're not persisted in the ViewState, they won't be registered with events. A similar question:
Problem with dynamic controls in .NET
Only 1 thing can cause this, you create the rb's on page_load and don't add them to a List<> or something similar and that object to Session. What you need to do is when you create the items, Add them to a List and add that list to Session["RadioButtons"] and if the Page.IsPostBack is true, load your controls one by one from your list which is kept in your session to your page.
I have a user control that contains a repeater, which in turn is nested in a default.aspx. When a user clicks a specific link on the page, the ajax post function is called which posts data to a method on default.aspx. All good so far! This method then calls a method within the user control, passing in the data, which in turn is used to requery, and rebind the repeater.
For some reason, the page bails when I try to do this last part?
If this seems converluted, it's because it doesn't seem possible in jquery to directly access user control methods.
Many thanks.
Rebinding a repeater control, which is an ASP.NET server control, is done on the server side, not the client side. If you want some grid behavior with ajax I suggest you look at a javascript based grid like for example jqGrid.
I have a site that I am currently working on in ASP.NET 2.0 using the usual WebForm stuff and ASP.NET AJAX 1.0. Is it possible to bind an event to a dynamically created control after the Page.Load event?
I have a table <td> element that I am dynamically creating similarly to this code:
' Create Link Button
lnk.ID = String.Format("lnkDetails_{0}", dr("Id"))
lnk.Text = dr("Name").ToString()
lnk.CommandArgument = dr("Id").ToString()
AddHandler lnk.Click, AddressOf DetailsLink_Click
cName.Controls.Add(lnk)
This this code is looped over for each row in a database (and of course more cells are added to the table, including an ImageButton with an event. The events work flawlessly when I execute this code during events leading up to and including Page.Load. I need to be able to fill this table with current data, which is updated during a btnClick Event elsewhere on the page, which occurs after this Page_Load event, so I am populating with old data. If I change this code to Page.LoadComplete, events stop working.
This data is a summary display of various components of an application, things like somebody's name, which when updated on a 'detail' form, updates the database by partial postback (a requirement), then it needs to show the update in this 'summary' section after an update. Currently it takes 2 postbacks to actually see the change in the 'summary' section, so effectively the summary is 1 step behind the changes (clear as mud?)
What would be the best way for me to populate this table with current data (which is available during/after Page.LoadComplete), but still have an event fire when a link is clicked (the event causes an UpdatePanel to display the 'detail' form).
I also have jQuery at my disposal and the usual ASP.NET AJAX methods, also javascript is a requirement for the website, so I do not need to degrade for unsupported browsers.
This is my first ASP.NET web application and need some help figuring out the best way to make this happen (I'm well versed in PHP, Django and the usual ways to do web forms - things like having multiple forms on one page o_O).
Update:
There really isn't a good way to bind control events to controls after Page_Load. The overall architecture of the pages is there is one ASP.NET form encompassing the entire page, there is only 1 aspx page. I am using master pages (however it doesn't have any obvious implications to my issue).
The page is split into a left and right 'pane', the left is a summary of all the data (in an update panel), the right 'pane' has 6 'tabs' implemented each as their own user control, each with several form fields and an update button all in it's own UpdatePanel.
An update on any of these tabs only refreshes the summary panel (UpdatePanel.update()) and its own panel. The 'refreshing' and event binding of dynamic controls of the summary from the db happens during Page_Load and the Update Button event updates db data. (The control event happens after Page_Load). I want to avoid doing a double post to get the summary to update, any thoughts are helpful.
You need to postback the whole page after your data changes in the 'btnClick Event elsewhere on the page'. It sounds like you have an UpdatePanel and it sounds like this is catching the postback of your btnClick event handler. Put the btnClick outside the UpdatePanel or change its triggers so that your btnClick forces a postback/refresh of your data. Or, redesign your table so it's AJAXly-refreshed when you click on btnClick, it's hard to get you more details without knowing more about the structure of your page and controls.
Good luck!
You can bind to an event whenever you want. It's just a simple event after all. But not all places might be suitable because you have to take into account when the event fires. And in most cases this happens between Page_Load and Page_PreRender. That includes the click event on a LinkButton. In general, I would recommend to add your dynamically created controls in the Page_Init stage.
You have to add the controls before Page.Load in order to maintain ViewState between postbacks, so use the OnInit event handler for that.
But once they're added, you should be able to bind event handlers (such as OnClick) at any point during or after the Page.Load... for example in your grid's ItemDataBound (or something like) or in the Page.PreRender.
I have a page results page (you get there after submitting your search query elsewhere) whit a whole bunch of gridviews for different type of data objects.
Obviously, some of the queries take longer than the others. How can I make each gridview render as soon as it has the data it needs?
This has been tricky for me because it must work on a postback as well as a pageload. Also, the object data sources just fire automatically on page load/postback; I'm not calling any methods programatically to get the data. Will I have to change this?
#Gareth Jenkins
The page will execute all of the queries before returning even the first update panel, so he won't save any time there.
The trick to do this is to move each of your complex gridviews into a user control, in the user control, get rid of the Object DataSource crap, and do your binding in the code behind.
Write your bind code so that it only binds in this situation:
if (this.isPostBack && ScriptManager.IsInAsyncPostback)
Then, in the page, programaticly refresh the update panel using javascript once the page has loaded, and you'll get each individual gridview rendering once its ready.
Could you put the DataGrids inside panels that have their visibility set to false, then call a client-side javascript function from the body's onload event that calls a server side function that sets the visibility of the panels to true?
If you combined this with an asp:updateProgress control and wrapped the whole thing in an UpdatePanel, you should get something close to what you're looking for - especially if you rigged the js function called in onload to only show one panel and call a return function that showed the next etc.