vb.net 带有 DropDownList 控制参数的 SqlDataSource 不读取值
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SqlDataSource with DropDownList Control Parameter doesn't read value
提问by LukeGeneva
I have a drop down list that bound to a SqlDataSource.
我有一个绑定到 SqlDataSource 的下拉列表。
I have another drop down list that's bound to a different SqlDataSource.
我有另一个绑定到不同 SqlDataSource 的下拉列表。
The second SqlDataSource has the first drop down as a Control Parameter.
第二个 SqlDataSource 将第一个下拉列表作为控制参数。
I'm trying to do this...
我正在努力做到这一点...
<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:
但我没有得到任何结果。但是，如果我将第二个 SqlDataSource 的控制参数设置为文本框，它就可以工作。例如，这有效：
<asp:ControlParameter ControlID="txt" Name="param"
PropertyName="Text"
ConvertEmptyStringToNull="true" />
txt.Text = "someValue"
dropDown2.DataBind()
Any ideas why this is?
任何想法这是为什么？
采纳答案by LukeGeneva
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.
我最终弄清楚了这一点。问题是下拉菜单试图绑定两次，很像这个问题中的问题。
I used the suggestion made by Joel Etherton, and now it works perfectly. Although I used a hidden control rather than a label.
我使用了 Joel Etherton 提出的建议，现在效果很好。虽然我使用了隐藏控件而不是标签。
