DropDownLists in 2 separate updatepanels only work once, then dont.

Hey, i have 2 dropdownlists, both databound to my sql server, the first one simply selects anything from the "catagories" database. Autopostback is enabled. The next one is a select to the subcatagories database, with an inner join to catagories on the catagory_id column..

The idea here was to make an ajax enabled cascading databound dropdownlist, and it DOES work... but only once. i tried making the trigger the indexChanged event of the 1st dropdown list, but i have the same results. If i change catagories more than once, i will not get a subcatagory change..

Any ideas?

So not sure why DropDownList1 is in an UpdatePanel, but DropDownList2 is the issue here eh and is in a panel, and has a dependant control, being the first drop down list.

So the second one, add a Trigger like this;

<asp:AsyncPostbackTriggerControlID="DropDownList1"EventName="SelectedIndexChanged"/>

Is that any help? Post a snippet of your page here.

Cheers,

Steve

You should use the Cascading Dropdown of Ajax Control Toolkit, it is specially developed for this purpose. Checkout the live demo of it:
http://www.asp.net/AJAX/Control-Toolkit/Live/CascadingDropDown/CascadingDropDown.aspx

It says AsyncPostbackTrigger was a unknown element... Here's my code:

Catagory:<BR /><asp:DropDownList id="DropDownList1" runat="server" DataValueField="Catagory_ID" DataTextField="Catagory" DataSourceID="SqlDataSource2" AutoPostBack="True"></asp:DropDownList><asp:UpdatePanel id="UpdatePanel1" runat="server" >
 <contenttemplate>
SubCatagory:<BR /><asp:DropDownList id="ddlSubCat" runat="server" DataValueField="SubCatagory_ID" DataTextField="SubCatagory" DataSourceID="ddlsubCatagory"></asp:DropDownList>

<asp:SqlDataSource id="SqlDataSource2" runat="server" SelectCommand="SELECT [Catagory], [Catagory_ID] FROM [db_Catagories]" ConnectionString="<%$ ConnectionStrings:floofieConnectionString %>"></asp:SqlDataSource><BR /><asp:SqlDataSource id="ddlsubCatagory" runat="server" SelectCommand="SELECT db_SubCatagories.SubCatagory, db_SubCatagories.SubCatagory_ID FROM db_Catagories INNER JOIN db_SubCatagories ON db_Catagories.Catagory_ID = db_SubCatagories.Catagory_ID WHERE (db_Catagories.Catagory_ID = @.catid)" ConnectionString="<%$ ConnectionStrings:floofieConnectionString %>"><SelectParameters>

<asp:ControlParameter PropertyName="SelectedValue" Name="catid" ControlID="DropDownList1"></asp:ControlParameter>
</SelectParameters>
</asp:SqlDataSource>
</contenttemplate>

KaziManzurRashid:

You should use the Cascading Dropdown of Ajax Control Toolkit, it is specially developed for this purpose. Checkout the live demo of it:
http://www.asp.net/AJAX/Control-Toolkit/Live/CascadingDropDown/CascadingDropDown.aspx

That looks really nice, is there any way of getting the web service code for vb.net?

Can you post the complete markup of UpdatePanel. If any of your dropdown is outsite the update panel set its AutoPostback=true and create AsyncPostbackTrigger in Update Panel which points to that dropdownlist.

KaziManzurRashid:

Can you post the complete markup of UpdatePanel. If any of your dropdown is outsite the update panel set its AutoPostback=true and create AsyncPostbackTrigger in Update Panel which points to that dropdownlist.

Sorry bout that, thought i had it all.

Catagory:<BR /><asp:DropDownList id="DropDownList1" runat="server" DataValueField="Catagory_ID" DataTextField="Catagory" DataSourceID="SqlDataSource2" AutoPostBack="True"></asp:DropDownList><asp:UpdatePanel id="UpdatePanel1" runat="server"> <contenttemplate>SubCatagory:<BR /><asp:DropDownList id="ddlSubCat" runat="server" DataValueField="SubCatagory_ID" DataTextField="SubCatagory" DataSourceID="ddlsubCatagory"></asp:DropDownList> <BR /><asp:SqlDataSource id="SqlDataSource2" runat="server" SelectCommand="SELECT [Catagory], [Catagory_ID] FROM [db_Catagories]" ConnectionString="<%$ ConnectionStrings:floofieConnectionString%>"></asp:SqlDataSource><BR /><asp:SqlDataSource id="ddlsubCatagory" runat="server" SelectCommand="SELECT db_SubCatagories.SubCatagory, db_SubCatagories.SubCatagory_ID FROM db_Catagories INNER JOIN db_SubCatagories ON db_Catagories.Catagory_ID = db_SubCatagories.Catagory_ID WHERE (db_Catagories.Catagory_ID = @.catid)" ConnectionString="<%$ ConnectionStrings:floofieConnectionString%>"><SelectParameters><asp:ControlParameter PropertyName="SelectedValue" Name="catid" ControlID="DropDownList1"></asp:ControlParameter></SelectParameters></asp:SqlDataSource></contenttemplate> <triggers><asp:AsyncPostBackTrigger ControlID="DropDownList1" EventName="SelectedIndexChanged"></asp:AsyncPostBackTrigger></triggers> </asp:UpdatePanel>

I acctually fixed it... the problem was, there was 3 other updatepanels, and they all need to be set to conditional.

I cant beleive i didnt see that in the first place.

DropDownList2.DataValueField = DropDownList1.SelectedValue

Hello, I have a webpage with 2 DDL controls. DDL1.SelectedValue = DDL2.DataValueField. Everthing works fine if I have DDL1 AutoPostBack checked. I would like to eliminate the postbacks. Below is my code. I do not know why it doesn't work.

Thanks! Steve

ProtectedSub DropDownList1_SelectedIndexChanged(ByVal senderAsObject,ByVal eAs System.EventArgs)Handles DropDownList1.SelectedIndexChanged

Dim strDataTextFieldAsString

DropDownList2.DataValueField = DropDownList1.SelectedValue

strDataTextField = DropDownList1.SelectedValue

strDataTextField = strDataTextField &"text"

DropDownList2.DataTextField = strDataTextField

EndSub

<body>

<formid="form1"runat="server">

<div>

<asp:ScriptManagerID="ScriptManager1"runat="server">

</asp:ScriptManager>

<asp:UpdatePanelID="UpdatePanel1"runat="server">

<ContentTemplate>

<asp:SqlDataSourceID="SqlDataSource1"runat="server"ConnectionString="<%$ ConnectionStrings:ConnectionString %>"SelectCommand="SELECT * FROM [Futures]"></asp:SqlDataSource>

<asp:SqlDataSourceID="SqlDataSource2"runat="server"ConnectionString="<%$ ConnectionStrings:ConnectionString %>"SelectCommand="SELECT * FROM [Months]"></asp:SqlDataSource>

<asp:DropDownListID="DropDownList1"runat="server"Style="z-index: 100; left: 342px; position: absolute; top: 86px"DataSourceID="SqlDataSource1"DataTextField="Text"DataValueField="Value"></asp:DropDownList>

<asp:DropDownListID="DropDownList2"runat="server"Style="z-index: 102; left: 616px; position: absolute; top: 86px"DataSourceID="SqlDataSource2"></asp:DropDownList>

</ContentTemplate>

<Triggers>

<asp:AsyncPostBackTriggerControlID="DropDownList1"EventName="SelectedIndexChanged"/>

</Triggers>

</asp:UpdatePanel>

</div>

</form>

</body>

SelectedIndexChanged is a server-side event which occurs only after a postback. If you inserted a breakpoint, you'd find that the program never gets there.

DisturbedBuddha:

SelectedIndexChanged is a server-side event which occurs only after a postback. If you inserted a breakpoint, you'd find that the program never gets there.

So what do I do to fix that?

Thanks Steve

Set AutoPostBack="true" for the dropdownlist and just place the dropdownlist in its own updatepanel to hide the visible refresh.

Hello, I already have my dropdownlist1 in an updatepanel with autopostback="true" and the whole page refreshes. If autopostback="false" nothing happens.

Please look at my code on top again.

Thanks for the help

Steve

DropDownList SelectedIndexChanged not fire (Autopostback - true!)

1<asp:DropDownList ID="SectionsDDL" runat="server" DataSourceID="SectionsObDS"2AutoPostBack="True" OnSelectedIndexChanged="SectionsDDL_SelectedIndexChanged"3DataTextField="titleName" DataValueField="id">4</asp:DropDownList>56<asp:UpdatePanel ID="UpdatePanel1" runat="server">7<ContentTemplate>8<asp:Panel ID="sectData" runat="server">9<asp:Label ID="tstlbl" runat="server" />10</asp:Panel>11</ContentTemplate>12<Triggers>13<asp:AsyncPostBackTrigger ControlID="sectionsDDL" EventName="SelectedIndexChanged" />14</Triggers>15</asp:UpdatePanel>

Everything is ok when I choose any item in DDL but first. When I choose first SelectedIndexChanged not fire.

I tried to find answer on forum and could not.

it sounds like your first item is selected when the dropdown loads so if you pick that answer the selected index never changes. Try adding an additional item called Not Selected or choos one or something along those lines as the first item in the list then everytime you should postback.

AjaxButter

Or you could change the SelectedIndex property to -1

DropDownList and AutoPostBack - Cannot Get the Actual Selected Value

Hello,

I have an update Panel that contains 2 DropDownLists, one of which has an AutoPostBack that eventually populates the other. The problem is that, although it works (the autopostback), i am always getting the last value added to the dropdown list by binding. THat is, i do not get the value that was selected when the event was fired. What could be wrong?

Can I see the code that you are using?. It seems to me that the selected value is being lost somewhere.

German Afanador