C# 将DropDownList的返回对象绑定到asp:DropDownList Web表单

为了帮助重用一些代码，我想生成DropDownList对象，并将它们分配给ASP.NET C#中的web表单字段

我似乎无法将我的对象（DropDownList）绑定到我的Web表单。这样做合适吗？有更好的办法吗？我知道我会在其他web表单上使用这个下拉列表，很多人都喜欢它。我想把所有这些放在一个我可以调用的类中

下面是我返回下拉对象的方法

在我的网络表单上，它是一个简单的

<asp:DropDownList ID="dd_name" runat="server"></asp:DropDownList>

我还试过Bind和其他东西

---

这可能吗？有更好的方法吗？

我已经调整了您的代码，使您能够将数据绑定到dropdownlist

protected ICollection ddNames() {

        string selectSQL = "mysql stuff";

        string connString = "my string";
        SqlCommand cmd = new SqlCommand(selectSQL, conn);
        SqlDataReader reader;
    // Create a table to store data for the DropDownList control.
     DataTable dt = new DataTable();

     // Define the columns of the table.
     dt.Columns.Add(new DataColumn("NewItemTextField", typeof(String)));
     dt.Columns.Add(new DataColumn("NewItemValueField", typeof(String)));

     dt.Rows.Add(CreateRow("Unassigned", "999999", dt));
        try  {
            conn.Open(); 
            reader = cmd.ExecuteReader();
            while ( reader.Read() )  {
                    // Populate the table with sample values.
                    dt.Rows.Add(CreateRow(DataHelpers.GetUserFirstLastFromID(Convert.ToInt32(reader["someid"])), reader["someid"].ToString(), dt));
            }
            reader.Close();
        }   catch (Exception ex)   {
             throw ex;
        }   finally    {

                if (conn != null)  {
                    conn.Dispose();
                    conn.Close();
                }
         }

    return dt;

    }

  DataRow CreateRow(String Text, String Value, DataTable dt)
  {

     // Create a DataRow using the DataTable defined in the 
     // CreateDataSource method.
     DataRow dr = dt.NewRow();

     // This DataRow contains the NewItemTextField and NewItemValueField 
     // fields, as defined in the CreateDataSource method. Set the 
     // fields with the appropriate value. Remember that column 0 
     // is defined as NewItemTextField, and column 1 is defined as 
     // NewItemValueField.
     dr[0] = Text;
     dr[1] = Value;

     return dr;

  }

最后，您对方法的调用和对dropdownlist的绑定将是：

 // Specify the data source and field names for the Text 
        // and Value properties of the items (ListItem objects) 
        // in the DropDownList control.
        dd_name.DataSource = ddNames();
        dd_name.DataTextField = "NewItemTextField";
        dd_name.DataValueField = "NewItemValueField";

        // Bind the data to the control.
        dd_name.DataBind();

        // Set the default selected item, if desired.
        dd_name.SelectedIndex = 0;

---

灵感来自

哦，回答得不错！这很有效。虽然我没有返回Icollection，而是返回了DataTable@Firemarble我很高兴这是你想要的：-）

protected ICollection ddNames() {

        string selectSQL = "mysql stuff";

        string connString = "my string";
        SqlCommand cmd = new SqlCommand(selectSQL, conn);
        SqlDataReader reader;
    // Create a table to store data for the DropDownList control.
     DataTable dt = new DataTable();

     // Define the columns of the table.
     dt.Columns.Add(new DataColumn("NewItemTextField", typeof(String)));
     dt.Columns.Add(new DataColumn("NewItemValueField", typeof(String)));

     dt.Rows.Add(CreateRow("Unassigned", "999999", dt));
        try  {
            conn.Open(); 
            reader = cmd.ExecuteReader();
            while ( reader.Read() )  {
                    // Populate the table with sample values.
                    dt.Rows.Add(CreateRow(DataHelpers.GetUserFirstLastFromID(Convert.ToInt32(reader["someid"])), reader["someid"].ToString(), dt));
            }
            reader.Close();
        }   catch (Exception ex)   {
             throw ex;
        }   finally    {

                if (conn != null)  {
                    conn.Dispose();
                    conn.Close();
                }
         }

    return dt;

    }

  DataRow CreateRow(String Text, String Value, DataTable dt)
  {

     // Create a DataRow using the DataTable defined in the 
     // CreateDataSource method.
     DataRow dr = dt.NewRow();

     // This DataRow contains the NewItemTextField and NewItemValueField 
     // fields, as defined in the CreateDataSource method. Set the 
     // fields with the appropriate value. Remember that column 0 
     // is defined as NewItemTextField, and column 1 is defined as 
     // NewItemValueField.
     dr[0] = Text;
     dr[1] = Value;

     return dr;

  }

 // Specify the data source and field names for the Text 
        // and Value properties of the items (ListItem objects) 
        // in the DropDownList control.
        dd_name.DataSource = ddNames();
        dd_name.DataTextField = "NewItemTextField";
        dd_name.DataValueField = "NewItemValueField";

        // Bind the data to the control.
        dd_name.DataBind();

        // Set the default selected item, if desired.
        dd_name.SelectedIndex = 0;