c# - ASP :gridview filter using listbox cannot make multiple selection

Question

我有这个 asp:gridview，我在其中使用 mySql 存储过程显示数据。我有一个名为 ddlstatus 的列表框，我用它来过滤数据。我使用 View 状态来显示从列表框中选择的数据。问题是我想在此列表框中进行多项选择并显示其上的每个选择的数据，但当它只显示初始选择的数据时。

客户端代码如下:

<asp:Label ID="lblstat" Text="status" Visible="false" runat="server"></asp:Label>
<asp:ListBox ID="ddlstatus" runat="server" OnSelectedIndexChanged="DropDownChange" AutoPostBack="true" AppendDataBoundItems="true" SelectionMode="Multiple"></asp:ListBox>

<asp:GridView ID="gdvTM" runat="server" ControlStyle-Width="100%"  AutoGenerateColumns="False" DataKeyNames="ID" OnRowDeleting="gdvTM_RowDeleting" PageSize="5" CssClass="cssgridview" AlternatingRowStyle-BackColor="#d5d8dc">
    <Columns >
       <asp:TemplateField HeaderText="Current Status">
         <ItemTemplate >
             <asp:Label ID="lblcstat" runat="server" Text='<%# Eval("status") %>'></asp:Label>
        </ItemTemplate>
      </asp:TemplateField>
    </Columns>
</asp:GridView>

服务器端代码如下:

private void BindDropDownList()
{
    PopulateDropDown(ddlstatus, lblstat.Text);
}
private void PopulateDropDown(ListBox ddl, string columnName)
{
    ddl.Items.Clear();
    ddl.DataSource = BindDropDown(columnName);
    ddl.DataTextField = columnName;
    ddl.DataValueField = columnName;
    ddl.DataBind();
    ddl.Items.Insert(0, new ListItem("Please select", "0"));
}
private void BindGrid()
{
    DataTable dt = new DataTable();
    String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;
    MySqlConnection con = new MySqlConnection(strConnString);
    MySqlDataAdapter sda = new MySqlDataAdapter();
    MySqlCommand cmd = new MySqlCommand("GetTMData");
    cmd.CommandType = CommandType.StoredProcedure;  
    string statusVal = null;
    if (ViewState["stat"] != null && ViewState["stat"].ToString() != "0")
    {
        statusVal = ViewState["stat"].ToString();
    }
    cmd.Parameters.AddWithValue("statusVal", statusVal);
    cmd.Connection = con;
    sda.SelectCommand = cmd;
    sda.Fill(dt);
    gdvTM.DataSource = dt;
    int i = dt.Rows.Count;
    gdvTM.DataBind();
    this.BindDropDownList();
    TableCell cell = gdvTM.HeaderRow.Cells[0];
    setDropdownselectedItem(ViewState["stat"] != null ? (string)ViewState["stat"] : string.Empty, ddlstatus);
}
private void setDropdownselectedItem(string selectedvalue, ListBox ddl)
{
    if (!string.IsNullOrEmpty(selectedvalue))
    {
         ddl.Items.FindByValue(selectedvalue).Selected = true;

    }
}
protected void DropDownChange(object sender, EventArgs e)
 {
      ListBox dropdown = (ListBox)sender;
      string selectedValue = dropdown.SelectedItem.Value;
      switch (dropdown.ID.ToLower())
      {
          case "ddlstatus":
             ViewState["stat"] = selectedValue;
             break;
      }

      this.BindGrid();
 }

private DataTable BindDropDown(string columnName)
{
    string username = uName.Text;
    String strConnString = System.Configuration.ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;
    MySqlConnection con = new MySqlConnection(strConnString);
    MySqlCommand cmd = new MySqlCommand("SELECT DISTINCT (" + columnName + ") FROM approved WHERE tm = @tm AND " + columnName + " IS NOT NULL", con);
    MySqlDataAdapter sda = new MySqlDataAdapter(cmd);
    cmd.Parameters.AddWithValue("@tm", username);
    DataTable dt = new DataTable();
    sda.Fill(dt);
    return dt;
}

下面是MySql存储过程:

CREATE DEFINER=`root`@`localhost` PROCEDURE `GetTMData`(in statusVal varchar(45))
BEGIN
SELECT *
   FROM approved
   WHERE (statusVal IS NULL
                OR status = statusVal)
         order by date desc;
END

我怎样才能做到这一点？提前致谢。

Answer 1

请将列表框设为多个

<asp:ListBox id="ListBox1" 
           Rows="6"
           Width="100px"
           **SelectionMode="Multiple"** 
           runat="server">

         <asp:ListItem Selected="True">Item 1</asp:ListItem>
         <asp:ListItem>Item 2</asp:ListItem>
         <asp:ListItem>Item 3</asp:ListItem>
         <asp:ListItem>Item 4</asp:ListItem>
         <asp:ListItem>Item 5</asp:ListItem>
         <asp:ListItem>Item 6</asp:ListItem>

      </asp:ListBox>

然后在服务器端void SubmitBtn_Click(Object sender, EventArgs e) {

     Message.Text = "You chose: <br />";

     // Iterate through the Items collection of the ListBox and 
     // display the selected items.
     foreach (ListItem item in ListBox1.Items)
     {

        if(item.Selected)
        {

           Message.Text += item.Text + "<br />";

        }

     }

  }