DropDownList.SelectedValue not updating with external input
I am having trouble with a dropdownlist control not working for the dropdownlist.selectedvalue event.
The dropdownlist populates at page load fine and all values are in the control, but the control simply will not change value when prompted in a in the code. I am not using a client click event of the control to change the selected value - but instead trying to change it programmatically from the input from another page.
<asp:UpdatePanel ID="DataUpdate" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:Table ID="Table1" runat="server" Width="100%" CellPadding="0" CellSpacing="0" BorderStyle="None"
Font-Names="Arial" Font-Size="12" ForeColor="#003366">
<asp:TableRow runat="server">
<asp:TableCell runat="server" ColumnSpan="2" Width="100%" HorizontalAlign="Center">
<asp:Label ID="Label31" runat="server" Text="Select Date Range For Capability Analysis" Font-Names="Arial"
Font-Size="12" ForeColor="#336699"></asp:Label><br />
<br />
</asp:TableCell>
</asp:TableRow>
<asp:TableRow runat="server">
<asp:TableCell runat="server" ColumnSpan="2" Width="100%" HorizontalAlign="Center">
<asp:Label ID="Label29" runat="server" Text="Most Distant Date: " Font-Names="Arial"
Font-Size="12" ForeColor="#336699"></asp:Label>
<asp:DropDownList ID="ScndDateCal" runat="server" DataSourceID="DateDataSource"
DataValueField="Cur_Date" AutoPostBack="True" ViewStateMode="Enabled">
</asp:DropDownList>
<asp:Label ID="Label28" runat="server" Text="Most Recent Date: " Font-Names="Arial"
Font-Size="12" ForeColor="#336699"></asp:Label>
<asp:DropDownList ID="FrstDateCal" runat="server" DataSourceID="DateDataSource"
DataValueField="Cur_Date" AutoPostBack="True" ViewStateMode="Enabled">
</asp:DropDownList>
<asp:SqlDataSource ID="DateDataSource" runat="server"
ConnectionString="<%$ ... %>"
ProviderName="<%$ ... %>"
SelectCommand="SELECT [Cur_Date] FROM [DataTable] WHERE ([DieNumber] = ?) AND ([PartNumber] = ? or [PartNumber] = 'All') AND ([MetricName] = ?) ORDER BY Cur_Date DESC"><%--[PartNumber], <%--AND ([PartNumber] = ?)--%> <%--ORDER BY RecordID DESC--%>
<SelectParameters>
<asp:Parameter DefaultValue="Die Number" Name="DieNumber" Type="String" />
<asp:Parameter DefaultValue="Part Number" Name="PartNumber" Type="String" />
<asp:Parameter DefaultValue="Metric Name" Name="MetricName" Type="String" />
</SelectParameters>
</asp:SqlDataSource><br /><br />
</asp:TableCell>
</asp:TableRow>
</asp:Table>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="FrstDateCal" EventName="SelectedIndexChanged" />
<asp:AsyncPostBackTrigger ControlID="ScndDateCal" EventName="SelectedIndexChanged" />
</Triggers>
</asp:UpdatePanel>VB.Net
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
PartNoVal.Text = Session("prtnoval")
DieNoVal.Text = Session("dienoval")
MetricVal.Text = Session("metricval")
ViewState("xmaxscale") = Session("xmaxscale")
ViewState("xminscale") = Session("xminscale")
DateDataSource.SelectParameters("DieNumber").DefaultValue = DieNoVal.Text
DateDataSource.SelectParameters("PartNumber").DefaultValue = PartNoVal.Text
DateDataSource.SelectParameters("MetricName").DefaultValue = MetricVal.Text
DateDataSource.DataBind()
FrstDateCal.DataBind()
ScndDateCal.DataBind()
BindChart()
Else
BindChart()
End If
End Sub
Protected Sub FrstDateCal_SelectedIndexChanged() Handles FrstDateCal.SelectedIndexChanged
FrstDateCal.SelectedValue = ViewState("xmaxscale")
DataUpdate.Update()
End Sub
Protected Sub ScndDateCal_SelectedIndexChanged() Handles ScndDateCal.SelectedIndexChanged
ScndDateCal.SelectedValue = ViewState("xminscale")
DataUpdate.Update()
End Sub
ASKER
Yes, those session values are the values to use. Yes, I tried doing it in Page_Load as well.
Try the Page_PreRender event instead. Regardless, the values need to already be available in the control before they can be selected. The Page Lifecycle comes into play here.
ASKER
Yes, the values are available in the control. All values are loaded fine in the control, but the programmatic select command will simply not select the target value (that is present) in the control.
Understood, but I'm talking about:
1. Debugging the code so that you can verify that at the point of time when it tries to set the value that it's availalble.
2. Nothing is overwriting the setting after that point.
1. Debugging the code so that you can verify that at the point of time when it tries to set the value that it's availalble.
2. Nothing is overwriting the setting after that point.
ASKER
Yes, that is when it is verified to be populated - during debugging. I verified that the full list of available data points from the database are loaded. The verification of the loaded data is done during debugging at the point when the SelectedValue command is invoked.
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ASKER
Thanks Kelvin,
I'll try this and let you know.
I'll try this and let you know.
According to the documentation, the SelectedValue property is a getter, not a setter.I don't think the documentation says that.
On the contrary : "The SelectedValue property can also be used to select an item in the list control by setting it with the value of the item."
Did you try setting them in the Page_Load event?