I have a GridView control where if the user click on the auto-generated edit button. A window will pop up using modal pop-up extender with a drop down list for user to select. The problem is the SelectedIndexChanged event will not fire if AutoPostBack is set to false.
But if I set the AutoPostBack to true the pop-up will go away without firing the SelectedIndexChanged event.
Is it possible to have a control with AutoPostBack set to true inside the modal pop-up?
Please put below code on drop down server side change event
modalpopup.show();
updatepanel.update();
where modalpopup is "ID" of modalpopupextender
and updatepanel is "ID" of updatepanel
The problem is the selectedindexchange
event will not fire if autopostback is
set to false...
I'm not sure that statement is strictly true. Isn't it a case that if autopostback is false, the SelectedIndexChange event fires during the next postback? So if you change the index, then click a Submit button, that's when the index change event is fired.
This isn't much good if you need server code to run to respond to the index change while the popup is still showing, but otherwise, you can still respond to the index change.
If you need to change something in the popup in response to the index change, you can always use client-side javascript.
You can use an UpdatePanel to resolve this problem. Wrap the DropDownList and any other controls that might give similar issue inside of an UpdatePanel, inside of the pop-up control. This will allow the pop-up to continue showing, while executing your postback code at the right time.
Related
Hi I'm having a really strange issue here. I have an ImageButton and Gridview, both of which I create on runtime. The Image button is a seperate control on the webform and is not linked in anyway to the Gridview. What I am trying to achieve is when the user completes the editing of a line in the GridView and clicks on the update row button, I perform a set of calculations on the input entered. If an error is found with the data entered, I then make visible the ImageButton which when clicked displays the error message. The function I am using to make visible or hide the Image button through
picCross.Style.Value = "display: none;"
and
picCross.Style.Value = "display: block;"
gets called on the Page.PreRender function. What I have discovered is that I am able to make changes to the ImageButton (changing the button's tooltip, setting its Style's value ) during a postback not fired by the GridView, such as when the user clicks on a button else where on the web form. If however I try making changes to the Imagebutton during the post back event of the GridView, such as when the user clicks on the edit row or update row button/link. The changes are not saved. What is even more strange is I do not have such an issue with labels. I can change the text of labels regardless on whether the change was made during the postback fired off by the Gridview control.
I have tried setting the ImageButton's EnableViewState to true and false but neither makes a difference. I have tried the same approach with panels and the same thing occurs, I can't change its properties during a postback caused by the gridview. My GridView has EnableViewState = True
P.S I'm binding the GridView on runtime too. Only my GridView's RowUpdating event fires. The RowUpdated event does not fire. I was hoping to try changing the ImageButton on RowUpdated, not that I think it would have made much of a difference anyway.
You should create the dynamic controls (Gridview and ImageButtons) in the PreInit event. Init event if you have a Master Page.
I have two radio button on my asp.net page, with AutoPostBack = True
When I click on either of those, they each set a flag SaveData=False
However, when I click on them, the page_load event occurs first, so the page_load event saves the data, then the radiobutton_OnCheckedChanged event is triggered.
How can I trigger the OnCheckedChanged before the page_load event?
You can't.
You need to read up on the page lifecycle.
You can't trigger the OnCheckedChanged before radiobutton_OnCheckedChanged because that's the normal page life cycle.
You can check in Page_Load if Page.IsPostBack is true or not, and then don't save (or save) the data.
Troy - you will have to take care of this on the client side (javascript / jquery).
Your AutoPostBack = True causes the form to do a postback which calls page load.
Its all about how the page lifecycle and server side events work.
You can't the page always needs to load before events can be fired. This has to do with control creation, view state management, control state, etc.
What you want to do in your Page_Load is something like:
if(!this.IsPostBack)
{
// Do the stuff you want on the initial page load
}
Anything that you do not want to happen when the radio buttons are clicked, put it inside the if {} block. IsPostBack indicates that the page is processing a post-back event, which is what happens when you click one of your radio buttons.
You can't change the order/sequence of event handler execution. However you may move the code inside the page_load to another event handler.
I have two update panels and in the second update panel i have asp.net button and onclick of the button in codebehind i have disabled it like btnAddSecurity.Enabled = false;
When I disable the button i enable a cancel button before it and on cancel button when i try to enable the btnAddSecurity.Enabled = true it simply doesn't work. Both of my updatepanels updatemode is conditional. what is the problem?
thanks
I am assuming cancel button is in the different updatepanel. Then add follwing line to your button click code..
UpdatePanel1.Update();
For more information refer this..
How UpdatePanel Controls Are Refreshed
If the UpdateMode property is set to Always, the UpdatePanel control’s content is updated on every postback that originates from anywhere on the page. This includes asynchronous postbacks from controls that are inside other UpdatePanel controls, and postbacks from controls that are not inside UpdatePanel controls.
If the UpdateMode property is set to Conditional, the UpdatePanel control’s content is updated when one of the following is true:
• When the postback is caused by a trigger for that UpdatePanel control.
• When you explicitly call the UpdatePanel control's Update method.
• When the UpdatePanel control is nested inside another UpdatePanel control and the parent panel is updated.
I forgot to mention this asp.net 2.0.
The user control has a unique id and it is loaded in the PageLoad event.
The user control is loaded into a panel and the panel is inside of a webpart.
The dropdown has autopostback set to true.
EnableViewState = true on the dropdown.
The ListItems are created in the dropdowns pre-render event method.
This is why I don't understand why it is not firing, the dropdown is the only thing that causes postback on this user control.
The event methods for the dropdown should occur since the user control is loaded in the page load method on postback again right?
Make sure there is no OnLoad or PageLoad event that is rebinding the datasource of the dropdown list. Rebinding the data with a new set of data may cause the clickhandler to not ever get executed.
make sure you have if (!Page.IsPostBack) around dropdownlist.datasource = and dropdownlist.databind()
I am not sure if this is your problem, but it is the most common.
Try with EnableViewState set to
true for the DropDownList
If the ViewState is set to false, on post back the selected Index gets back to default which is normally the first Item. First item, if selected, does not cause SelectedIndexChange event to fire
I'm writing an ASP.Net webform with some DropDownList controls on it. Then user changes selected item in one of dropdowns, ASP.Net doesn't seem to handle SelectedIndexChanged event until form is submitted with a 'Submit' button click.
How do I make my dropdowns handle SelectedIndexChanged instantly?
P.S. It's a classic question I have answered too many times, but it seems no one asked it before on stackoverflow.
Setting the AutoPostback property to true will cause it to postback when the selection is changed. Please note that this requires javascript to be enabled.
You need to set the AutoPostBack property of the list to true.
Also, if you're populating the contents of the drop down list from the code behind (getting the contents of the list from a database, for example) - make sure you're not re-binding the data in every postback.
Sometimes people are caught out by binding the drop-down in the page load event without putting it in an If Not IsPostBack. This will cause the event not to fire.
The same is also true of repeaters and ItemCommand events.
if you are populating the dropdown list during page load then each time the page postback it will reload the list thus negating your postback method.
you need to be sure to load the dropdownlist only if (!ispostback)
Set the AutoPostBack property of DropDownList to true.