This is what I'm doing: Using jquery, I'm popping up a "form" over the page that lets the user search for branches of the company and select the one they want. When the form pops up, they can type in a textbox, and it will do AJAX requests back to the server to return the top n results for what they've entered, and those results will be put into a list for them. I want the user to be able to select one by clicking a link that says "select" or something, and at that point I want it to do a PostBack have the Branch Selector control that this is in change it's SelectedBranch property to the newly selected branch. I've got this all working right now with a hard coded list of LinkButtons, but how do I do the same thing with a dynamic list of links inserted with jquery?
Look at the HTML that gets emitted for your hard coded LinkButtons. You'll see that each one calls the JavaScript __doPostBack function when clicked. I believe this function takes two arguments: a control ID and an extra command argument you can use for your own purposes.
I would suggest adding a single control to the page whose only job is handling events for the dynamic links. Then, when you are creating the links with jquery, make each one call __doPostBack, passing the event handling control's ID for the first argument and some other string for the second argument that identifies which link was clicked. In the Click event for the handling control, look at the second argument value and do what you need to do.
The short answer is... you don't.
ASP.NET relies on the Viewstate for the current state of the controls, including items in a DropDownList or similar control. Dynamically updating a list on the client will not modify the viewstate, so will not be available on the back end.
The general workaround for this is to just add a hidden field which updates/stores the current selection via js on the client side. Then read it from this field on the backend rather than List.SelectedValue.
Related
I have an asp button which I am using in 2 different places (appending to a new place and adding a class using jquery under certain conditions).
I need to slightly alter the function that runs when this button is clicked depending on whether or not this button has a given class. Is this possible??
So something like this...
if myASPButton hasclass("xyz") then
...
end if
i'm using vb.net for what it's worth.
It's not possible, clicking a button causes a postback, the only information posted back is form data. Modifications to the HTML client-side wont be reflected severside.
You will need to make a hidden field and populate the value of the hidden field and use that for checking severside.
I'm creating a custom ASP.Net GridView and I want to be able to alter the __EVENTARGUMENT value but I can't figure out how to capture the returned value on the server side.
I'm creating the ability to have a collapsible representation, so the first level is the standard GridView and I will insert additional rows via JavaScript if they expand the first level row.
My problem is how to create a link on the selecond level rows that posts back with custom data.
I believe the RaisePostBackEvent is where this value gets passed into; the base GridView class allows you to override it, so you should be able to tap into it there.
This is a part of the IPostBackEventHandler interface.
HTH.
Use __dopostback to raise the postback from javascript. Use the correct parameters so that this will be mapped to the right event
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 form with several text fields, a couple of drop down lists, and a custom asp.net control.
The requirement I have is that when the values of certain fields ( some are in the main form, some are inside the control ) the user will be alerted that the settings will not take place unless they also restart the processing and will have the option to reset it. If they exercise this option by pressing on the restart button, we execute an additional restart() method call on the server side on top of everything else.
In order to create this alert system I need to know when these required fields have changed. For the fields in the main form/page I store the original values in hidden fields when the page gets created (possible because the page is static). Then when the submit button is pressed I check the current values against the original values stored. If any of them differ I will alert the user.
For the fields in the custom control, I created a boolean property that indicates whether changes in the fields of interest took place. This control is highly dynamic contains a variable number of lists, some of them with over 100 items that can be selected or deselected. So this boolean property is able to identify if the changes I am looking for took place.
The problem is I need to get the value of this property when the user clicks on Submit, otherwise it will not contain the right value. But at the same time I want to avoid a postback. I do not want the whole page to reload. I want to get that value asynchronously somehow.
Since the whole page is stateless the question is how do I accomplish this? How do I accomplish the call to the property? And after I make the call and I get the result where do I store it so it's accessible from javascript code on the client side.
You can try putting a timer control in your ajax panel. Then on a set interval, you will evaluate the boolean property in your code behind.
Alternatively you can check the hidden field "changed" event using JavaScript or jQuery
http://api.jquery.com/change/
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.