Web Forms :: Fire DropDownList SelectedIndexChanged Event Without Reloading Page
May 7, 2015
I have a gridview and dropdownlist, let say the content of dropdownlist is YEAR and the content of gridview is Name and Year. Now for everytime I change the Value of dropdownlist the content of gridview will change but it will not load the page
I have a form which has some dropdownlists (ListItems "Yes" "No"). I use my form to Enter data & submit to database and use same form to Edit aswell. Like I redirect to this form from another page with a QueryString. If there is a QueryString then SELECT * FROM Table WHERE ID = QueryString's value & fill all the controls in the form like
I have certain things to do when DropDownList.SelectedValue = "Yes" so I can use SelectedIndexChanged event handler & AutoPostBack="true" when submitting form for the first time. Now when I edit the information(Data filled from table as stated above). How can i automatically fire all events like DropDownlist SelectedIndexChanged in the page_Load iteslef so that all the things that are supposed to be done when DropDownList.SelectedValue = "Yes". I'm posting my test code for reference to explain what I'm trying to do. This is just the Idea. I have something else to deal with if i can get this stright. I need to dynamically add controls based on the values of DropDownList. please suggest some thing guys.
I create a dropDownList in code-behind, in selectIndexChange of another dropDownList, and add this new dropDownList to page using a placerHolder, everthing its ok, but new dropdownlist selectIndexChange event dont fire!
I have in my MasterPage a DropDownList that appears in all my Pages. I want it to run a specific code when user select another item in the list, but the event SelectedIndexChanged in the MasterPage doesn't work. How can I do to get this event working?
I'm using VS2008. When a dataset is bound to the DataSource of a ListView, SelectedIndexChanged event does not fire. If I used DataSourceID instead, it has no problem. But SelectedIndexChanging event fires for both.
why and how I can get SelectedIndexChanged event fired when DataSource is used?
I've got a UserControl that's used inside of an UpdatePanel. The UserControl is a fairly simple form that appears via a ModalPopupExtender (which is also part of the UserControl). There are four DropDownLists, as well as some other UI elements. Three of the four DropDownLists have AutoPostBack="true", with SelectedIndexChanged events that fire on the server and cause some of the other DropDownLists to rebind. Two of the three DDL's that AutoPostBack are working fine. One of them, which I only just added, is showing some strange behavior. Let's say I bind five Items to it: 1, 2, 3, 4, 5. I set the SelectedIndex to 0, which makes 1 the selected item. If I select 5 and then 1 and keep toggling back and forth, everything works fine. The postback occurs and SelectedIndexChanged fires. Every time. If I ever select 2 or 4, the postback occurs but SelectedIndexChanged does not fire. Every time.
If I ever select 3, something bizarre happens and sometimes the value of the DDL reverts to 1. Even though breakpoints seem to show that it's not rebinding and no unexpected code is running. I know your first instinct will probably be that I'm wrong about the rebinding code not running, but I have literally been staring at the debugger for hours trying to find my mistake. Lots of breakpoints. I don't get it -- this really isn't that complicated. But obviously I am missing something. I've put about four hours into this so far and I think I'm just grinding at this point. I could use another perspective.
HTML (and by the way, DropProtocolCycleID is the problem control): <asp:Panel ID="PanelPopupAssign" runat="server" Style="display:none; cursor: move; width:325px; background-color:Transparent;"> <BlueUI:Panel runat="server" ID="PanelPatientProtocol" Width="500px" HeaderText="Assign Protocol"> <table cellspacing="5"> <tr> <td style="width:150px;"></td> <td style="width:50px;"></td> <td style="width:125px;"></td> </tr> <tr runat="server" id="TableRowCategory"> <td align="right">Category:</td> <td colspan="2"> <asp:DropDownList runat="server" ID="DropProtocolCategories" CausesValidation="false" autopostback="true"/> </td> </tr> <tr> <td align="right">Protocol:</td> <td colspan="2">..............................
I have one dropdownlist control which populates values to other controls. Means upon selecting item in dropdownlist, related data is populated in other controls. I have also assigned dropdownlist's autopostback to TRUE. Everything is working good as far as dropdown has more than one item.
Whenever there is only one item, selectedindexchanged event is not fired (obviously.....) and eventually the data is not populated to other controls.
How could I get rid of this scenario? I mean which event should I use to avoid this?
At this time, I have just added the first item as something like "---Select Item---" , so when end-user has to select different item and thus the selecteditemindexchanged is fired. no biggie... but just wondering if proper solution is available....
Getting an unexpected event firing dropdownlist's selectedIndex event. When I try to redirect from another page by a linkButton. I just changing dropdownlist selectedIndex.Its okay.But after that When I attempt to redirect to another page,DropDownList's selectedIndex event firing (before linkButton Onclick event).But I am not changing any thing in dropdownlist.Somehow its event firing.
also any page viewstates is default (not off).But loading webcontrols into masterpage Page_Load like this :
if this dropdownlist selectedIndexchanged event firing. Because of I am loading webcontrols each masterpage's PageLoadEvent.
What do you prefer this may the reason of this unexpected event firing ? if so. Do you have a better technic to load controls Just for one time and not each pageLoad.maaybe a caching technic I am missing or shoult I use substution.
I couldnt find the main reason why a dropdownlist selectedIndexchanged event firing without I changed anything on that dropdownlist.
what reasons may cause this problem ? if you say viewstate its turned on defaultly. any other reason you know why ?
In our asp.net web application we load the dropdown list boxes in the page load. We than set the SelectedValue of each dropdown list box to an object from session. We have event handlers for many of the SelectedIndexChanged events of the drop down lists boxes, but these do not get executed when we set the selected value programmatically.
Someone else mentioned this is by design, and only when a user manually changes the drop down list selected index, will the event get raised.
I would think this is a common scenario of wanting the selectedindexchanged event handled when setting the selectedvalue/selectedindex/listitem's selected property, of a DropDownList. What is the suggested way to handle this? Is there a significant drawback of creating a custom control inherited from DropDownList that has the functionality of raising this event when changing the SelectedIndex or SelectedValue?
I want to execute code written in a dropdown selectedindexchanged event from some another user defined function.
For this i m writing:
It works when use it in page_load (means the code in ddlMyDropDown1_SelectedIndexChanged is executed) but when i write the same line in another function it gives error "The name sender doesnot exists in current context".
in my web form i have a department dropdown box, in its selectedIndexChanged event i have to fill the equipment dropdown box and in equiment dropdown selectedIndexChanged i have to fill out the other textboxs.
the depratment dropdown box get its value from sqldatasource.
what i want is when i run the page, it shows the very first deparment in the list, and according to that it should pop up the values in the other fields, means it should show the values in the equipment dropdownbox and from that one it should pop up the values in the other textbox.
here is my selected indexchanged event for department dropdownbox
I ask for a date, on OnTextChanged event i bind data with a SqlDataSource to a dropdownlist and also bind data to a repeater passing the dropdownlist SelectedIndex (i use SqlDataSource too and ControlParameter to link the dropdownlist and the repeater) On my repeater during the ItemDataBound event i create dynamic dropdownlist controls, my code is :
On the Page_load event of my page i bind the data & recreate the control :
Everything works fine, datas are bound and SelectedIndexes are restore on every postback.
The probem occurs when user change different dropdownlists, if he choose to change the 1st dropdownlist the event is fire (normal), after if he modifies another dropdownlist the event is fire twice, if he modifies a 3rd time the event is fire 3 time etc...