c# - ASP.NET DropDownList 问题

Question

[...]
public DataSet ReturnPromoMagazinesDs()
{

    MySql.Data.MySqlClient.MySqlConnection mysqlConnection = new MySql.Data.MySqlClient.MySqlConnection(this.connectionString);

    MySql.Data.MySqlClient.MySqlCommand mysqlCommand = new MySql.Data.MySqlClient.MySqlCommand("SELECT id, magazine_name FROM `magazines`", mysqlConnection);

    MySql.Data.MySqlClient.MySqlDataAdapter mysqlAdaptor = new MySql.Data.MySqlClient.MySqlDataAdapter(mysqlCommand);

    DataSet ds = new DataSet();

    mysqlAdaptor.Fill(ds, "magazines");

    return ds;
}

[...]
protected void Page_Load(object sender, EventArgs e)
{
        DataSet ds = new DataSet();
        ds = coreObject.ReturnPromoMagazinesDs();

        DropDownList1.DataSource = ds;
        DropDownList1.DataTextField = ds.Tables["magazines"].Columns["magazine_name"].ColumnName;
        DropDownList1.DataValueField = ds.Tables["magazines"].Columns["id"].ColumnName;
        DropDownList1.DataBind();

}

[...]
<asp:dropdownlist id="DropDownList1" runat="server"></asp:dropdownlist>

上面的代码工作正常，直到我获取始终为 1(表中的第一个值)的 DropDownList1.SelectedValue 。表中的值并不是造成这种情况的原因，如果我手动将项目添加到 DropDownList，一切都会正常。什么会导致这种情况？

Answer 1

当您将 Page_Load 方法中的所有代码包装在以下内容中时，它是否可以正常工作:

if (!IsPostBack) { /* Code as in the original post */ }