SqlDataSource with DropDownList Control Parameter doesn't read value

Question

I have a drop down list that bound to a SqlDataSource.

I have another drop down list that's bound to a different SqlDataSource.

The second SqlDataSource has the first drop down as a Control Parameter.

I'm trying to do this...

<asp:SqlDataSource ID="sqlDataSource2" runat="server"
    ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
    SelectCommand="SELECT * FROM Test WHERE Param = @param;"
    CancelSelectOnNullParameter="true">
    <SelectParameters>
        <asp:ControlParameter ControlID="dropDown1" Name="param"
            PropertyName="SelectedValue"
            ConvertEmptyStringToNull="true" />
    </SelectParameters>
</asp:SqlDataSource>

dropDown1.SelectedValue = "someValue"
dropDown2.DataBind()

but I don't get any results. However, if I set the second SqlDataSource's Control Parameter to a text box, it works. For example, this works:

<asp:ControlParameter ControlID="txt" Name="param"
    PropertyName="Text"
    ConvertEmptyStringToNull="true" />

txt.Text = "someValue"
dropDown2.DataBind()

Any ideas why this is?

are you sure you have your datatextfield and datavaluefield arranged properly? Plus do you have autopostback set to true for both controls? — briskovich
– briskovich, Commented Mar 22, 2013 at 23:31

Community · Accepted Answer · 2017-05-23 12:04:56Z

1

I ended up figuring this one out. The problem was that the drop down was attempting to bind twice, much like the problem in this question.

I used the suggestion made by Joel Etherton, and now it works perfectly. Although I used a hidden control rather than a label.

edited May 23, 2017 at 12:04

CommunityBot

11 silver badge

answered Mar 26, 2013 at 14:21

LukeGeneva

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