如何将页面加载时的网格视图与下拉列表绑定

本文关键字：视图 网格 下拉列表 绑定 加载 | 更新日期: 2023-09-27 18:24:19

我有一个下拉列表，可以按类别进行搜索。我需要帮助在页面加载时绑定我的网格视图，但同时，我还有一个选择命令作为投票。我知道pageload事件中有一些代码，比如Databinding。但对于我的情况，我需要将select命令链接到一个按钮来更新投票。如果我对它进行数据绑定，我就无法获取数据密钥名称来更新我的投票计数器。有没有任何方法可以在不删除gridview本身中的DataSourceID的情况下绑定gridview？

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>

c#代码

 protected void btnVote_Click(object sender, EventArgs e)
{
    int reviewid = Convert.ToInt16(GridView1.SelectedDataKey.Value);
    SqlConnection conn = new SqlConnection(@"Data Source=.'SQLEXPRESS;AttachDbFilename=|DataDirectory|'Database.mdf;Integrated Security=True;User Instance=True");
    string sqlstmt = "select Votes from Review where ReviewID = '" + reviewid + "'";
    SqlCommand comm = new SqlCommand(sqlstmt, conn);

    try
    {
        conn.Open();
        SqlDataReader read = comm.ExecuteReader();

        if (read.Read())
        {
            int votes = (int)read["Votes"];
            votes += 1;
            string updatestatement = "Update Review set Votes= '" + votes + "' Where ReviewID = '" + reviewid + "'";
            SqlCommand command = new SqlCommand(updatestatement, conn);
           read.Close();
            command.ExecuteNonQuery();
        }

    }
    finally { 
        conn.Close();
        GridView1.DataBind();
    }
}
     protected void SelectionChange(object sender, EventArgs e)
  {
    int stored = ddlCat.SelectedIndex;
    if (stored == 0)
    {
        SqlDataSource1.SelectCommand = "SELECT * from Review ORDER BY [Votes] DESC  ";

    }
    else { } 
}

如何将页面加载时的网格视图与下拉列表绑定

您应该从GridView实现RowCommand事件。你已经有了CommandField，所以做这样的事情：

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，假设您将使用Select按钮来激发更新魔法。这里是SelectIndexChanging。

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绑定GridView：

在这种情况下，您需要检索在下拉列表中选择的值。执行以下设置以从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>

正在发生什么：

  • 每次在下拉列表中选择一个值时，都会进行Postback（AutoPostback="true"）
  • Page.PreRender事件之后，DataSource控件[SqlDatSource here]执行所需的查询并检索数据。因此，SqlDataSource将使用选定的DropDownList值。因此，无需担心以任何方式更改/操纵DataSourceID

2.）"但对于我的情况，我需要将select命令链接到更新投票的按钮"'

在这种情况下，您在网格视图内有一个选择按钮，在网格视图外有一个"投票"按钮，但在页面的某个位置。因此，一旦您在网格视图中选择了任何一行，请单击"投票"按钮。您可以像往常一样访问SelectedRow和Index。

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

请注意，"Vote"按钮的Click事件在DataSource控件执行查询之前激发&检索数据。因此，一旦您像当前一样更新btnVote_click事件中的投票计数，就不需要再次绑定数据。你的这部分代码对我来说似乎很好。

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