下拉列表未在转发器 Web 应用程序中显示正确的选定值 ASP.NET

本文关键字：NET ASP 显示转发器 Web 应用程序下拉列表 | 更新日期: 2023-09-27 18:31:12

我有几个 ASP.NET 中继器，其中有下拉列表，它们都需要填充正确的信息，然后显示它正在显示的每个数据行的选定值。在一个中继器（CompanyRepeater）中，选择正确的选择值。在另一个中继器（SoldRepeater）中，没有选择正确的选择值。因此，CompanyRepeater中的下拉列表确实有效，但SoldRepeater中的下拉列表不起作用。两个中继器的代码相同，我无法弄清楚为什么第二个中继器不起作用。两个下拉列表都填充了正确的信息，但第二个转发器不显示正确的选定值。请帮助我找出为什么没有选择正确的选定值。下面是我的代码。如果还有需要帮助我的信息，请告诉我。任何帮助都非常感谢。首先是我的前端代码。

<asp:Repeater ID="CompanyRepeater" runat="server" OnItemDataBound="CompanyRepeater_ItemDataBound" OnItemCommand="CompanyRepeater_ItemCommand">
   <ItemTemplate>
      <table>
         <tr>
            <td colspan="3" style="text-align: center;">
               <h3 style="font-weight: bold;">Company</h3>
            </td>
         </tr>
         <tr>
            <td>Event Date:
               <br />
               <asp:TextBox ID="txtDate" runat="server" Text='<%#Eval("Date") %>'></asp:TextBox>
               <asp:Label ID="lblCompID" runat="server" Text='<%#Eval("CompID") %>' Visible="false"></asp:Label>
            </td>
            <td rowspan="2">Notes:
               <br />
               <asp:TextBox ID="txtNotes" TextMode="MultiLine" Height="100px" Text='<%#Eval("Notes") %>' runat="server"></asp:TextBox>
            </td>
            <td>OldName
               <br />
               <asp:TextBox ID="txtOldNameChange" Text='<%#Eval("OldName") %>' runat="server"></asp:TextBox>
            </td>
         </tr>
         <tr>
            <td>Country:
               <asp:DropDownList ID="ddlCountry" AutoPostBack="true" runat="server" OnSelectedIndexChanged="ddlCountry_SelectedIndexChanged"></asp:DropDownList>
               <br /> State:
               <asp:DropDownList ID="ddlState" runat="server"></asp:DropDownList>
            </td>
            <td>New Name
               <br />
               <asp:TextBox ID="txtNewNameChange" runat="server" Text='<%#Eval("NewName") %>'></asp:TextBox>
            </td>
            <td rowspan="3" style="width: 50px; float: right;">
               <asp:Button ID="btnUpdateName" runat="server" Text="Update" CommandName="Update" />
               <br />
               <asp:Button ID="btnDelete" runat="server" Text="Delete" OnClientClick="return confirm('Are you sure you want to delete this record?')" CommandName="Delete" CommandArgument='<%#Eval("CompID") %>' />
            </td>
         </tr>
      </table>
   </ItemTemplate>
   <SeparatorTemplate>
      <p>&nbsp;</p>
      <br />
   </SeparatorTemplate>
</asp:Repeater>
<hr />
<asp:Repeater ID="SoldRepeater" runat="server" OnItemDataBound="SoldRepeater_ItemDataBound" OnItemCommand="SoldRepeater_ItemCommand">
   <ItemTemplate>
      <table>
         <tr>
            <td colspan="3" style="text-align: center;">
               <h3 style="font-weight: bold;">Sold Event</h3>
            </td>
         </tr>
         <tr>
            <td>Event Date:
               <br />
               <asp:TextBox ID="txtSoldDate" runat="server" Text='<%#Eval("EventDate") %>'></asp:TextBox>
               <asp:Label ID="lblCompID" runat="server" Text='<%#Eval("CompID") %>' Visible="false"></asp:Label>
            </td>
            <td rowspan="2">Notes:
               <br />
               <asp:TextBox ID="txtSoldNotes" TextMode="MultiLine" Height="100px" Text='<%#Eval("Notes") %>' runat="server"></asp:TextBox>
            </td>
            <td>Sold to Company
               <br />
               <asp:TextBox ID="txtSoldTo" Text='<%#Eval("SoldToCompany") %>' runat="server"></asp:TextBox>
               <br /> Sold to Type
               <asp:DropDownList ID="ddlSoldTo" runat="server"></asp:DropDownList>
            </td>
            <td rowspan="2">
               <asp:Button ID="btnUpdate" runat="server" Text="Update" CommandName="Update" CommandArgument='<%#Eval("CompID") %>' />
               <br />
               <asp:Button ID="btnDelete" runat="server" Text="Delete" OnClientClick="return confirm('Are you sure you want to delete this record?')" CommandName="Delete" CommandArgument='<%#Eval("CompID") %>' />
            </td>
         </tr>
      </table>
   </ItemTemplate>
   <SeparatorTemplate>
      <p>&nbsp;</p>
      <br />
   </SeparatorTemplate>
</asp:Repeater>

这是我的后端代码

protected void Page_Load(object sender, EventArgs e)
{
   _cID = Convert.ToInt32(Request.QueryString["CompID"]);
   if (!Page.IsPostBack)
   {
      PopulateCompanyRepeater();
      PopulateSoldEvent();
   }
}
private void PopulateCompanyRepeater()
{
   DALAccessData a = new DALAccessData(connString);
   _listInfo = a.GetCompInfo(_cID);
   CompanyRepeater.DataSource = _listInfo;
   CompanyRepeater.DataBind();
}
private void PopulateSoldEvent()
{
   DALSectionAccessData a = new DALSectionAccessData(connString);
   _listEvents = a.GetSoldEvents(_cID);
   SoldRepeater.DataSource = _listEvents;
   SoldRepeater.DataBind();
}
protected void CompanyRepeater_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
   if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
   {
      DropDownList ddl = (DropDownList)e.Item.FindControl("ddlCountry");
      DropDownList ddl2 = (DropDownList)e.Item.FindControl("ddlState");
      Corp co = (Corp)e.Item.DataItem;
      Corp st = (Corp)e.Item.DataItem;
      SqlDataAdapter sda;
      DataSet ds = new DataSet();
      try
      {
         using(cn = new SqlConnection(connString))
         {
            string s = "SELECT DISTINCT a.Country_ID, a.CountryName FROM States c INNER JOIN Countries a ON a.Country_ID = c.Country_ID";
            cn.Open();
            sda = new SqlDataAdapter(s, cn);
            sda.Fill(ds);
            ddl.DataSource = ds.Tables[0];
            ddl.DataTextField = "CountryName";
            ddl.DataValueField = "Country_ID";
            ddl.DataBind();
            cn.Close();
         }
      }
      catch (Exception ex)
      {
         throw new Exception(ex.Message);
      }
      for (int i = 0; i < ddl.Items.Count; i++)
      {
         if (co.Country_ID == Convert.ToInt32(ddl.Items[i].Value))
         {
            ddl.Items[i].Selected = true;
         }
         else
         {
            ddl.Items[i].Selected = false;
         }
      }
      try
      {
         using(cn = new SqlConnection(connString))
         {
            string s = "SELECT DISTINCT StateName, StateID FROM States WHERE Country_ID = " + ddl.SelectedValue;
            cn.Open();
            sda = new SqlDataAdapter(s, cn);
            sda.Fill(ds);
            ddl2.DataSource = ds.Tables[0];
            ddl2.DataTextField = "StateName";
            ddl2.DataValueField = "StateID";
            ddl2.DataBind();
         }
      }
      catch (Exception ex)
      {
         throw new Exception(ex.Message);
      }
      for (int i = 0; i < ddl2.Items.Count; i++)
      {
         if (!String.IsNullOrEmpty(ddl2.Items[i].Value))
         {
            if (st.StateID == Convert.ToInt32(ddl2.Items[i].Value))
            {
               ddl2.Items[i].Selected = true;
            }
            else
            {
               ddl2.Items[i].Selected = false;
            }
         }
      }
   }
}
protected void ddlCountry_SelectedIndexChanged(object sender, EventArgs e)
{
   DropDownList ddl = (DropDownList)CompanyRepeater.Items[0].FindControl("ddlCountry");
   DropDownList ddl2 = (DropDownList)CompanyRepeater.Items[0].FindControl("ddlState");
   ddl2.Items.Clear();
   using(SqlConnection conn = new SqlConnection(connString))
   {
      using(SqlCommand cmd = new SqlCommand())
      {
         cmd.CommandText = "SELECT StateName, StateID FROM States WHERE Country_ID = " + ddl.SelectedValue;
         cmd.Connection = conn;
         conn.Open();
         using(SqlDataReader sdr = cmd.ExecuteReader())
         {
            while (sdr.Read())
            {
               ListItem _listStates = new ListItem();
               _listStates.Text = sdr["StateName"].ToString();
               _listStates.Value = sdr["StateID"].ToString();
               ddl2.Items.Add(_listStates);
            }
         }
      }
   }
   ddl2.AppendDataBoundItems = true;
   ddl2.Items.Insert(0, new ListItem("Select a State", "-1"));
   ddl2.SelectedIndex = -1;
}
protected void SoldRepeater_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
   if (e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem)
   {
      DropDownList ddl = (DropDownList)e.Item.FindControl("ddlSoldTo");
      int x = ((CorpEvents)e.Item.DataItem).SoldToTypeID;
      //Corp x = (Corp)e.Item.DataItem;
      SqlDataAdapter sda;
      DataSet ds = new DataSet();
      try
      {
         using(cn = new SqlConnection(connString))
         {
            string s = "SELECT SoldToTypeID, SoldToTypeName FROM SoldToType";
            cn.Open();
            sda = new SqlDataAdapter(s, cn);
            sda.Fill(ds);
            ddl.DataSource = ds.Tables[0];
            ddl.DataTextField = "SoldToTypeName";
            ddl.DataValueField = "SoldToTypeID";
            ddl.DataBind();
         }
      }
      catch (Exception ex)
      {
         throw new Exception(ex.Message);
      }
      for (int i = 0; i < ddl.Items.Count; i++)
      {
         if (x == Convert.ToInt32(ddl.Items[i].Value))
         {
            ddl.Items[i].Selected = true;
            //i = 9;
         }
         else
         {
            ddl.Items[i].Selected = false;
         }
      }
   }
}

我的数据访问层代码

public List <Corp> GetCompInfo(int a)
{
   List <Corp> _listInfo = new List <Corp> ();
   DataTable dt = new DataTable();
   DataSet ds = new DataSet();
   //create the connection and command objects
   SqlConnection connection = new SqlConnection(_dbConnection);
   SqlCommand command = new SqlCommand();
   //populate the command object
   command.Connection = connection;
   command.CommandText = "SELECT a.CompID, CONVERT(varchar(10), a.Date, 120) AS Date, a.Notes, b.StateID, b.OldName, b.NewName, c.Country_ID FROM NameChange b INNER JOIN CompanyInfo a ON a.CompID = b.CompID INNER JOIN States c ON c.StateID = b.StateID WHERE a.CompID = " + a;
   using(connection)
   {
      using(command)
      {
         connection.Open();
         ds.Load(command.ExecuteReader(), LoadOption.OverwriteChanges, new string[] {
            "MyTable"
         });
         dt = ds.Tables["MyTable"];
      }
   }
   foreach(DataRow row in dt.Rows)
   {
      Corp e = new Corp();
      e.CompID = Convert.ToInt32(row["CompID"].ToString());
      e.NewName = row["NewName"].ToString();
      e.OldName = row["OldName"].ToString();
      e.StateID = Convert.ToInt32(row["StateID"].ToString());
      e.Notes = row["Notes"].ToString();
      e.CountryID = Convert.ToInt32(row["Country_ID"].ToString());
      e.Date = Convert.ToDateTime(row["Date"].ToString());
      e.Date.ToShortDateString();
      _listInfo.Add(e);
   }
   return _listInfo;
}
public List <Corp> GetSoldEvents(int a)
{
   List <Corp> _listInfo = new List <Corp> ();
   DataTable dt = new DataTable();
   DataSet ds = new DataSet();
   //create the connection and command objects
   SqlConnection connection = new SqlConnection(_dbConnection);
   SqlCommand command = new SqlCommand();
   //populate the command object
   command.Connection = connection;
   command.CommandText = "SELECT a.CompID, a.Notes, a.Date, b.SoldToCompany, c.SoldToTypeName, c.SoldToTypeID FROM CompanyInfo a INNER JOIN SoldEvent b ON a.CompID = b.CompID INNER JOIN SoldToType c ON b.SoldToTypeID = c.SoldToTypeID WHERE a.CompID = " + a;
   using(connection)
   {
      using(command)
      {
         connection.Open();
         ds.Load(command.ExecuteReader(), LoadOption.OverwriteChanges, new string[] {
            "MyTable"
         });
         dt = ds.Tables["MyTable"];
      }
   }
   foreach(DataRow row in dt.Rows)
   {
      Corp e = new Corp();
      e.CompID = Convert.ToInt32(row["CompID"].ToString());
      e.SoldToCompany = row["SoldToCompany"].ToString();
      e.SoldToTypeName = row["SoldToTypeName"].ToString();
      e.SoldToTypeID = Convert.ToInt32(row["SoldToTypeID"].ToString());
      e.Notes = row["Notes"].ToString();
      e.EventDate = Convert.ToDateTime(row["Date"].ToString());
      e.EventDate.ToShortDateString();
      _listInfo.Add(e);
   }
   return _listInfo;
}

下拉列表未在转发器 Web 应用程序中显示正确的选定值 ASP.NET

恕

我直言，您设置所选值的方法相当麻烦。这整段代码：

for (int i = 0; i < ddl.Items.Count; i++)
{
   if (x == Convert.ToInt32(ddl.Items[i].Value))
   {
      ddl.Items[i].Selected = true;
      //i = 9;
   }
   else
   {
      ddl.Items[i].Selected = false;
   }
}

可以用单行替换：

ddl.SelectedValue = x.ToString();

此外，一旦找到匹配的值，您就会继续循环项目，而不是退出循环。

尝试这些更改，它们可能会为您解决问题。

我注意到的其他一些项目：

检索SoldToType的代码是为中继器。我建议检索此数据一次并引用它针对每个项目，而不是每次都转到数据库。

您的 SQL 代码对 SQL 注入是开放的。使用参数化查询，如下所示：

cmd.CommandText = "SELECT StateName, StateID FROM States WHERE Country_ID = @CountryID";
...
cmd.Parameters.AddWithValue("CountryID", ddl.SelectedValue);