Web Forms :: DropDownList SelectedIndexChanged Event Not Fired When Programatically Setting SelectedValue?
Oct 27, 2010
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?
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Jun 28, 2010
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
[URL]
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.
[Code]....
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May 3, 2010
[Code]....
A breakpoint is set on FillForm() and this method is called two times but I can't explain myself why this happens. I have client side javascript code, when the form is being send, the onsubmit method is also called twice... Where do I have to search?! Is it a (known) bug? Think I could get it to work with this Thread: [URL] But why is the event fired within the onblur-event when it's fired anyway??
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Feb 25, 2011
I'm using XmlDataSource as the datasource for a dropdownlist. Now I want to set the SelectedValue of the dropdown when the page initially loads. I tried the OnDataBound event of the dropdown in which I could see the total items but setting the SelectedValue didn't work. In OnDataBinding event, I couldn't even see the total items probably because the list isn't bound yet.
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Jul 21, 2010
I have a WebForms page that has two DropDownList controls on it that both contain a range of temperatures from 60-80 degrees, one for heating the other for cooling. They are declared in the .aspx as:
<asp:DropDownList ID="heating" runat="server" />
<asp:DropDownList ID="cooling" runat="server" />
The values for each list are populated in the code-behind using:
for(int i = 60; i <= 80; i++)
{
var listItem = new ListItem(i + " degrees", i.ToString());
heating.Items.Add(listItem);
cooling.Items.Add(listItem);
}
When I try to set the selected value for each DropDownList using the values in an object containing data loaded from the database using:heating.SelectedValue = myHome.avgHeatingTemp.ToString();
cooling.SelectedValue = myHome.avgCoolingTemp.ToString();
The SelectedValue for both lists is set first to the value in myHome.avgHeatingTemp, then to the value in myHome.avgCoolingTemp. Heres what the values are for each variable after each step of the process of setting the SelectedValues:
Initial State
heating.SelectedValue: 60
cooling.SelectedValue: 60 [code]....
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May 11, 2010
I have a ASP.Net webform with a DropDownList control. This Dropdown gets it's values from a states table in an ObjectDatasource. The Dropdown contains states spelled out.
If I try to set the drop down to:
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I get an error that the value does not exist in the dropdown even though it does exist. But if I pad the value with the correct number of spaces to the right, it works like so:
DropDownStates.SelectdValue = "Ohio "
or
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How can I either define the dropdown without trailing spaces in the value of the dropwdown or set the SelectedValue with adding trailing spaces?
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Mar 11, 2011
I'm populating a dropdownlist in a formview with a different datasource from the formview's. I need to set the selected value according to the value in the formview's datasource but I'm having a hard time doing that.
Here's the code:
<asp:FormView ID="FormView1" runat="server" DataKeyNames="ID"
DataSourceID="SqlDataSource1">
<EditItemTemplate> [code]....
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Nov 25, 2010
I have officially wasted about two days trying to figure out what the heck was going on with my asp.net page. I actually thought it was an issue with my updatepanel code, but after reading another post I was able to reproduce the same results. [URL]
I just manually added the following control to the page (no code behind for the listbox) and it is nested in an ajax tabcontrainer inside an updatepanel. If you set item 20 as selected the page flickers when loading that tab. I tried the css mentioned (style="overflow:hidden") on the tabcontainer,tab panel, update panel and dropdownlist, but no luck. Crazy select item 19 no flicker, 20 (which is actually the 21st item) and it does flicker. This is driving me insane. And yes this only occurs in FireFox ( running 3.6).
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Jan 8, 2010
I binded the dropdown from the table Languages, now it shows all the languages:
ViewData("Languages") =
New SelectList(objLang,
"SysLanguageID",
"LanguageName")
Now when I click the edit then the dropdown should show the selectedvalue based on the languageId that is in stored in the Preferences table under the user.If i give the third parameter as the selectedvalue it is showing the selected value but it is not showing the other languages.
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Dec 13, 2010
I have a databound dropdownlist on a page, where in the page_load I set the selectedValue (inside a 'not isPostBack').
Although the page displays fine and shows the correct item as selected.. inside the page_load if I try and get the selectedValue() and display it to the screen, I always get null... selectedIndex is -1.
I have a button, which when clicked refers to this ddl's selectedValue, and here it pulls through the the expected result.. so how come I can't see it immediately after setting it, while still in page_load?
edit: the code..
ddl declaration
<asp:DropDownList runat="server" ID="dlCountryList" DataSourceID="dsCountryList"
DataValueField="countrylistid" DataTextField="description">
</asp:DropDownList>
and the page_load
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
dlCountryList.SelectedValue = "GR"
Response.Write("*" + CStr(dlCountryList.SelectedIndex) + "*")
End Sub
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Nov 11, 2010
I have a bit of a problem with a DropDownList I am using. When the user changes the SelectedIndex, they get redirected to the same page, but with a query string on the end based on their selected value.
Because I'm not posting, and redirecting instead, the state of the dropdownbox is not saved, so it always defaults to the first one.But, if I save it in say a session, or set the selectedvalue according to the query string in Page_Load, when the user selects another listitem, the selection they have chosen is overridden by the selection delcared in Page_Load.
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Jul 9, 2010
In my current web application I have a listbox containing large number of elements. I have used an ajax listsearchextender to help the users in selecting the elements. I have set the autopostback property of listbox true. The application is working fine as expected in internet explorer. But in firefox while I am typing some text in search lable of listsearchextender the selectedIndexChanged event is fired and the page is posted back. So I am not able to selected the item properly using list search extender control. Can you please suggest me how can I stop the selectedIndexChanged event.
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Aug 16, 2010
I have a repeater with a DropDownList in it. I set the datasource of this list in the itembound event en set the selectedindex. When I debug the selectedindex is set, but when the page is done loading for all the item the default item is selected.
protected void Repeater1_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
var ddl = (DropDownList)e.Item.FindControl("DataFeedItems");
ddl.DataSource = FilterDropDownData();
ddl.DataTextField = "ColumnName";
ddl.DataValueField = "ColumnName";
ddl.DataBind();
[code]...
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Jun 22, 2010
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....
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Mar 2, 2011
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 :
[Code]....
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 ?
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Jan 11, 2011
I want to get dates from Database to a calendar > on a dropdownlist Selection.. This is what i was doing on page load
[Code]....
I tried using it in dropdownlist SelectedIndexChanged but something is not right! here is the rest of the code for dayrendar event and
[Code]....
What should i do ?
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Jan 8, 2011
i am using dropdownlist selectedindexchanged event , it is working with good speed in ie 6 or ie 7. But working slow in ie8.
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Apr 28, 2010
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?
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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
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Oct 5, 2010
I have a dropdownlist in a repeater and it's firing the SelectedIndexChanged event but in teh event handler I can not get the dataitem associated with the row that the DDL is in. Here is the code:
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Feb 5, 2011
I want to execute code written in a dropdown selectedindexchanged event from some another user defined function.
For this i m writing:
ddlMyDropDown1_SelectedIndexChanged(sender, e);
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".
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Feb 9, 2011
I have a DropDown which is bounded to an ObjectDataSource. On its data bound event, I am adding "--select--" value on the 0 index. I have a LinkButton on the page and on its client click, i am selecting different item on drop down (using JavaScript). Suppose there are 3 items like --select--, option1, option2 and option3 and now on link button's client click i selected option3, now if I select the default value "--select--", it does not fire the SelectedIndexChanged event. If I select any other value then it fires. Why does it not work for the default value?
[code]....
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Nov 18, 2010
I have a dropdownlist in DetailsView to which items are added programmatically during DataBound event. It is working fine in InsertItemTemplate, but in EditItemTemplate i am getting this error "'branchDDL' has a SelectedValue which is invalid because it does not exist in the list of items. Parameter name: value".
. Following is the code:
<asp:TemplateField
HeaderText="Course"
SortExpression="branchID">[code]....
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Aug 4, 2010
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 :
[Code]....
[Code]....
On the Page_load event of my page i bind the data & recreate the control :
[Code]....
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...
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Apr 21, 2010
I have some code which fires when user selects an item in dropdownlist. Now i want the same code to fire when i set selectedindex programmatically.
I have tried setting
ddlSystemLevelDCP.SelectedIndex=2;
and this as well
ddlSystemLevelDCP.SelectedValue="2";
None of them fires this event.However when user changes the selection,this event fires.Please tell me what am i missing.
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