在页面加载时将空值传递给sqldatasource中的存储过程

Question

I have some textboxes which are used to enter search values. I have a stored procedure that has 2 datetimes, 1 int and 1 char parameter. I attach my SqlDataSource to a TextBox and set the default value to null but when I run my project empty is passed to the stored procedure but my stored procedure expects a null value. How can I pass null with SqlDataSource bound to textboxes?

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:DB_MosquesAffairsConnectionString3 %>"
    SelectCommand="mqa.S_Conference_Select_Date"
    SelectCommandType="StoredProcedure" onload="SqlDataSource1_Load"
    onselecting="SqlDataSource1_Selecting">
    <SelectParameters>
        <asp:ControlParameter ControlID="TextBox1" DbType="Date" DefaultValue="null"
            Name="StartDate" PropertyName="Text" />
        <asp:ControlParameter ControlID="TextBox2" DbType="Date" DefaultValue="null" 
            Name="EndDate" PropertyName="Text" />
        <asp:ControlParameter ControlID="TextBox3" DefaultValue="null" 
            Name="ConferenceName" PropertyName="Text" Type="String" />
        <asp:ControlParameter ControlID="TextBox4" DefaultValue="null" 
            Name="ConferenceID" PropertyName="Text" Type="Int32" />
    </SelectParameters>
</asp:SqlDataSource>

Answer 1

You can use the following properties/attributes in ControlParameter

ConvertEmptyStringToNull="true" DefaultValue=""


  <SelectParameters>
                     <asp:ControlParameter ControlID="TextBox1" DbType="Date"     ConvertEmptyStringToNull="true" DefaultValue=""
                         Name="StartDate" PropertyName="Text" />
                     <asp:ControlParameter ControlID="TextBox2" DbType="Date"     ConvertEmptyStringToNull="true" DefaultValue=""
                         Name="EndDate" PropertyName="Text" />
                     <asp:ControlParameter ControlID="TextBox3"     ConvertEmptyStringToNull="true" DefaultValue="" 
                         Name="ConferenceName" PropertyName="Text" Type="String" />
                     <asp:ControlParameter ControlID="TextBox4"     ConvertEmptyStringToNull="true" DefaultValue=""
                         Name="ConferenceID" PropertyName="Text" Type="Int32" />
                 </SelectParameters>