C# 如何使用下拉列表在pageload处绑定gridview

我有一个按类别搜索的下拉列表。 我需要帮助在页面加载时绑定gridview，但同时，我还有一个select命令作为投票。 我知道pageload事件中存在诸如数据绑定之类的代码。但对于我的情况，我需要将select命令链接到一个按钮以更新投票。如果我对它进行数据绑定，我就无法获取数据键名称来更新投票计数器。 有没有办法绑定gridview，而不删除gridview本身中的DataSourceID

我的aspx代码如下

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
                        ConnectionString="<%$ ConnectionStrings:ConnectionString %>" 
                        SelectCommand="SELECT * FROM [Review] WHERE ([Category] = @Category)">
                        <SelectParameters>
                            <asp:ControlParameter ControlID="ddlCat" Name="Category" 
                                PropertyName="SelectedValue" Type="String" />
                        </SelectParameters>
                    </asp:SqlDataSource>



                      <asp:SqlDataSource ID="SqlDataSource2" runat="server" 
                        ConnectionString="<%$ ConnectionStrings:ConnectionString %>" 
                        SelectCommand="SELECT [Category] FROM [ReviewCategory]">
                        </asp:SqlDataSource>


                    <asp:DropDownList ID="ddlCat" runat="server" 
                        DataSourceID="SqlDataSource2" DataTextField="Category" 
                        DataValueField="Category" AutoPostBack="True" 
                        onselectedindexchanged="SelectionChange">
                    </asp:DropDownList>


<asp:GridView ID="GridView1" runat="server" Width="1114px" 
    Height="272px" AutoGenerateColumns="False" PageSize="5" 
        DataSourceID="SqlDataSource1" AllowPaging="True" DataKeyNames="ReviewID">
<Columns>

    <asp:BoundField DataField="Votes" HeaderText="Votes" 
        SortExpression="Votes" />
    <asp:BoundField DataField="Category" HeaderText="Category" 
        SortExpression="Category" />

    <asp:CommandField SelectText="VOTE as your FAVOURITE!" 
        ShowSelectButton="True" />
</Columns>

---

您应该从GridView实现

row命令

事件。您已经有了

命令字段

，因此请执行以下操作：

void GridView1_RowCommand(Object sender, GridViewCommandEventArgs e)
{
  //
  // Get the keys from the selected row
  //
  LinkButton lnkBtn = (LinkButton)e.CommandSource;    //the button
  GridViewRow myRow = (GridViewRow)lnkBtn.Parent.Parent;  //the row
  GridView myGrid = (GridView)sender; // the gridview
  int reviewid = Convert.ToInt32(GridView1.DataKeys[myRow.RowIndex].Value); //value of the datakey **strong text**

  // If multiple buttons are used in a GridView control, use the
  // CommandName property to determine which button was clicked.
  // In this case you are pressing the button Select, as ou already
  // defined this at the aspx code.
  if(e.CommandName=="Select")
  {
    // Put the logic from btnVote_Click here
  }
}

另一种方法可以是实现

SelectIndexChanging

或

SelectIndexChanged

，因为您将使用选择按钮触发更新魔法。下面是带有

selectIndexchange

的示例

void GridView1_SelectedIndexChanging(Object sender, GridViewSelectEventArgs e)
{

  // Get the currently selected row. Because the SelectedIndexChanging event
  // occurs before the select operation in the GridView control, the
  // SelectedRow property cannot be used. Instead, use the Rows collection
  // and the NewSelectedIndex property of the e argument passed to this 
  // event handler.
  int reviewid = Convert.ToInt32(GridView1.DataKeys[e.NewSelectedIndex].Value); //value of the datakey **strong text**

  // Put the logic from btnVote_Click here
}

---

让我们逐一了解您的需求：

1.）*使用DropDownList在PageLoad处绑定GridView：

在这种情况下，您需要检索dropdownList中选择的值。执行以下设置从DropDownList获取值

<asp:SqlDataSource ID="SqlDataSource2" runat="server" 
 ConnectionString="<%$ ConnectionStrings:ConnectionString %>" 
 SelectCommand="SELECT [Category] FROM [ReviewCategory] where Category=@Category">
<SelectParameters><asp:ControlParameter ControlID="ddlCat" Name="Category"
 PropertyName="SelectedValue" /></SelectParameters>
</asp:SqlDataSource>

---

请注意，“投票”按钮的单击事件在数据源控件执行查询和检索数据之前触发。因此，一旦您按照当前的操作更新btnVote_click事件中的投票计数，就无需再次绑定数据。这部分代码对我来说似乎很好。

我尝试了你的方法。。在sqlsoruce 2中添加控件样式后，我的下拉列表值消失..为什么这个soDropdownlist值消失？您正在使用“SqlDataSource2”在dropDownList中获取数据。那么，您可以检查第二个数据源是否确实正在获取数据吗？因为您没有对SqlDataSource2进行任何更改，所以它应该获取数据。

<asp:SqlDataSource ID="SqlDataSource2" runat="server" 
 ConnectionString="<%$ ConnectionStrings:ConnectionString %>" 
 SelectCommand="SELECT [Category] FROM [ReviewCategory] where Category=@Category">
<SelectParameters><asp:ControlParameter ControlID="ddlCat" Name="Category"
 PropertyName="SelectedValue" /></SelectParameters>
</asp:SqlDataSource>

protected void btnVote_Click1(object sender, EventArgs e)
{
     int i = CustomersGridView.SelectedIndex;
}