从下拉列表中传递数据

Question

我一直在尝试从两个dropdownlist（page1.aspx）传递选定的数据到（page2.aspx）我没有任何运气，因为它似乎没有被选中时传递数据。请帮助，这似乎并不困难，但我无法得到它的工作。在（page2.aspx）上，下拉列表中的数据将被传递给一个存储过程，所有结果都将在gridview中。

这里是我的代码：

Page1.aspx的

<asp:DropDownList ID="ddlState" runat="server" AutoPostBack="True" DataSourceID="SqlDataSource1" DataTextField="ST_Code" DataValueField="ST_Code" /> 
<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:dbConnection %>"SelectCommand="SELECT [ST_Code] FROM [State]"> 
</asp:SqlDataSource> City: <asp:DropDownList ID="ddlCity" runat="server" DataSourceID="SqlDataSource2" DataTextField="RS_City" DataValueField="RS_City" /> 
<asp:SqlDataSource ID="SqlDataSource2" runat="server" ConnectionString="<%$ ConnectionStrings:dbConnection %>"SelectCommand="ListbyStateSPROC"SelectCommandType="StoredProcedure">` 
     <SelectParameters> 
      <asp:ControlParameter ControlID="ddlState" Name="State" PropertyName="SelectedValue" Type="String" />  
     </SelectParameters> 
</asp:SqlDataSource> 

     <asp:Button ID="Submit" runat="server" Text="Submit" /> 
    &nbsp; 

</asp:Content> 

Page1.aspx.vb

Imports System.Data 
Imports System.Data.Common 
Imports System.Data.SqlClient 
Imports System.Web.UI.WebControls.DataGrid 
Imports System.Web.UI.WebControls.DropDownList 


Partial Public Class LiveEventSearch 
    Inherits System.Web.UI.Page 

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load 

    End Sub 

    Public Sub ddlState_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) 
     SqlDataSource2.SelectParameters.Clear() 
     SqlDataSource2.SelectParameters.Add(New Parameter("@State", DbType.String, ddlState.SelectedValue)) 
     ddlCity.DataBind() 


    End Sub 

    Protected Sub ddlCity_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ddlCity.SelectedIndexChanged 

    End Sub 


    Protected Sub Submit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Submit.Click 

    End Sub 
End Class 

Page2.aspx

<asp:GridView ID="GridView1" runat="server" AllowSorting="True" AutoGenerateColumns="False" 
     DataSourceID="SqlDataSource1" Style="z-index: 100; left: 324px; position: absolute; 
     top: 226px"> 
     <Columns> 
      <asp:BoundField DataField="Code" HeaderText="Code" ReadOnly="True" SortExpression="R_Code" /> 
      <asp:BoundField DataField="Name" HeaderText="Name" ReadOnly="True" SortExpression="R_Name" /> 
      <asp:BoundField DataField="Number" HeaderText="Number" ReadOnly="True" SortExpression="RS_Number" /> 
      <asp:BoundField DataField="Addr_1" HeaderText="Addr_1" ReadOnly="True" SortExpression="RS_Addr_1" /> 
      <asp:BoundField DataField="City" HeaderText="City" ReadOnly="True" SortExpression="RS_City" /> 
      <asp:BoundField DataField="State" HeaderText="State" ReadOnly="True" SortExpression="RS_State" /> 
      <asp:BoundField DataField="RS_Zip" HeaderText="RS_Zip" ReadOnly="True" SortExpression="RS_Zip" /> 
     </Columns> 
    </asp:GridView> 
    <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:dbConnection %>" 
     SelectCommand="ListbyCityStSPROC" SelectCommandType="StoredProcedure"> 
     <SelectParameters> 
      <asp:QueryStringParameter Name="City" QueryStringField="RS_City" Type="String" /> 
      <asp:QueryStringParameter Name="State" QueryStringField="ST_Code" Type="String" /> 
     </SelectParameters> 
    </asp:SqlDataSource> 

</asp:Content> 

Answer 1

有效地在每一页ASP.NET应用程序就像一个单独的应用程序本身并不会跨越页面，因此您需要实现一个保持SQLDataSource的类，以便跨页面调用它，或者需要实现一些方法在页面之间复制数据。

你也可以使用FindControl函数来查找所有网页的SqlDataSource：

SqlDataSource sql = (SqlDataSource)Page.Master.Findcontrol("SqlDataSource1");