Question

我发现会话模式为＆＃34; SQLServer＆＃34;时出现问题。我已在以下示例中隔离了该问题：

在使用.Net 3.5的Web应用程序中，我有以下项目：

1）两个班级：

[Serializable]
public class Foo
{
    private List<Bar> bars;

    public Foo(List<Bar> bars)
    {
        this.bars = bars;
    }

    public List<Bar> Bars
    {
        get { return bars ?? (bars = new List<Bar>()); }
    }
}

[Serializable]
public class Bar
{
    public int PropertyBar { get; set; }
}

2）用户控件

public partial class UserControl : UserControl
{
    public List<Bar> Bars
    {
        get { return Session["Bars"] as List<Bar>; }
        set { Session["Bars"] = value; }
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            Bars.Add(new Bar { PropertyBar = Bars.Last().PropertyBar+1});
        }
    }
}

3）带有用户控件和按钮的aspx页面：

public partial class _Default : Page
{
    public List<Bar> Bars
    {
        get
        {
            var foo = Session["Foo"] as Foo;
            if (foo != null)
            {
                return foo.Bars;
            }
            return null;
        }
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            var foo = new Foo(new List<Bar>{new Bar{PropertyBar = 1}, new Bar{PropertyBar = 2}});
            Session["Foo"] = foo;
            userControl.Bars = foo.Bars;
        }
        else
        {
            Bars.Add(new Bar { PropertyBar = 5 });
        }
    }

    protected void OnButton1Click(object sender, EventArgs e)
    {
        label.Text = string.Format("Default.aspx has {0} bars ({1}); UserControl has {2} bars ({3})",
            Bars.Count, Bars.Aggregate(string.Empty, (s, i) => s + i.PropertyBar + ",").TrimEnd(','),
            userControl.Bars.Count, userControl.Bars.Aggregate(string.Empty, (s, i) => s + i.PropertyBar + ",").TrimEnd(','));
    }
}

使用此：

<sessionState mode="SQLServer" timeout="20" allowCustomSqlDatabase="true"
 sqlConnectionString="Data Source=.;Initial Catalog=SessionDB;User Id=XXX;Password=YYY;"     />

我按下按钮，结果是：

 Default.aspx has 5 bars (1,2,3,4,5); UserControl has 4 bars (1,2,3,4)

但如果我使用它：

<!--<sessionState mode="SQLServer" timeout="20" allowCustomSqlDatabase="true"
 sqlConnectionString="Data Source=.;Initial Catalog=SessionDB;User Id=XXX;Password=YYY;" /> -->

我按下按钮，结果是：

Default.aspx has 5 bars (1,2,3,4,5); UserControl has 5 bars (1,2,3,4,5)

我的问题是：

1）为什么只有在会话模式为＆＃34; SqlServer＆＃34;？

时才会出现这种情况

2）我应该如何正确使用本例中的会话？

Answer 1

我对问题2的回答是：

public interface IHasBars
{
    List<Bar> Bars { get; }
}

public partial class _Default : Page, IHasBars
{
    //...
}

public partial class UserControl : UserControl
{
    private List<Bar> bars; 
    private List<Bar> Bars
    {
        get 
        {
            if (bars==null)
            {
                var hasBars = Page as IHasBars;
                if (hasBars != null)
                {
                    return bars = hasBars.Bars;
                }
                throw new InvalidOperationException("You can only use this userControl inside a IHasBars");
            }
            return bars;
        }
    }

    //...

这样总是使用相同的列表。但我仍然不明白为什么不然。

SessionState在会话模式更改时呈现不同的行为

1 个答案: