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我动态创建了几个仪表控件，将它们存储到一个类中，然后将它们添加到列表和会话变量中以供稍后检索。当我尝试从会话状态加载仪表时，未设置某些控制属性，例如“gauge.Gauge.Value”引发了“System.NullReferenceException”类型的异常。我的课看起来像这样：

public BoldGauge(ASPxGaugeControl gauge, string gaugeValue, string gaugeDataType, float gaugeMinValue, float gaugeMaxValue)
    {
        Gauge = gauge; // new ASPxGaugeControl(); 
        GaugeValue = gaugeValue; 
        GaugeDataType = gaugeDataType; 
        GaugeMinValue = gaugeMinValue; 
        GaugeMaxValue = gaugeMaxValue; 
    }

    public ASPxGaugeControl Gauge { get; set; }
    public string GaugeValue { get; set; } 
    public string GaugeDataType { get; set; } 
    public float GaugeMinValue { get; set; }
    public float GaugeMaxValue { get; set; } 
}

下面是我声明控件的方式，在底部，您可以看到我将它们添加到列表的位置、列表和会话。任何想法为什么会发生这种情况？我需要做一些特别的事情来在会话中存储控件吗？

ASPxDockPanel dockPanel = CreateDockPanel(layoutName, tableCellId, controlType, controlData, controlName);
            ASPxGaugeControl boldGaugeControl = new ASPxGaugeControl();

            string dockZonePanelId = "dockPanel" + tableCellId[tableCellId.Length - 1] + layoutName.Replace(".xml", "");
            //boldGaugeControl.ID = "gaugeControl" + dockZonePanelId;

            boldGaugeControl.ID = "gaugeControl" +gaugeVal; 
            boldGaugeControl.ClientInstanceName = "gaugeControl" +gaugeVal; // +gaugeVal;// dockZonePanelId  + layoutName.Replace(".xml", "");
            boldGaugeControl.EnableClientSideAPI = true;

            // Creates a new instance of the CircularGauge class and adds it
            // to the gauge control's Gauges collection.
            CircularGauge circularGauge = (CircularGauge)boldGaugeControl.AddGauge(GaugeType.Circular);

            // Adds the default elements (a scale, background layer, needle and spindle cap).
            circularGauge.AddDefaultElements();

            // Changes the background layer's paint style.
            ArcScaleBackgroundLayer background = circularGauge.BackgroundLayers[0];
            background.ShapeType = BackgroundLayerShapeType.CircularFull_Style2;

            // Customizes the scale's settings.
            ArcScaleComponent scale = circularGauge.Scales[0];
            scale.MinValue = minimumGaugeValue;
            scale.MaxValue = maximumGaugeValue;
            scale.Value = value;
            scale.MajorTickCount = 6;
            scale.MajorTickmark.FormatString = "{0:F0}";
            scale.MajorTickmark.ShapeType = TickmarkShapeType.Circular_Style1_2;
            scale.MajorTickmark.ShapeOffset = -9;
            scale.MajorTickmark.AllowTickOverlap = true;
            scale.MinorTickCount = 3;
            scale.MinorTickmark.ShapeType = TickmarkShapeType.Circular_Style2_1;
            scale.AppearanceTickmarkText.TextBrush = new SolidBrushObject(Color.Gray);

            // Changes the needle's paint style.
            ArcScaleNeedleComponent needle = circularGauge.Needles[0];
            needle.ShapeType = NeedleShapeType.CircularFull_Style3;

            // Adds the gauge control to the Page.
            boldGaugeControl.Width = 150;
            boldGaugeControl.Height = 150;
            boldGaugeControl.AutoLayout = true;
            boldGaugeControl.ControlStyle.BackColor = Color.Black;
            boldGaugeControl.EnableClientSideAPI = true;
            boldGaugeControl.ClientIDMode = ClientIDMode.Static;
            boldGaugeControl.Value = "25";

            dockPanel.Controls.Add(boldGaugeControl);

            BoldGauge gauge = new BoldGauge(boldGaugeControl, gaugeValue, controlData, minimumGaugeValue, maximumGaugeValue);

            boldGauges.Add(gauge);
            Session.Add("GaugesList", boldGauges);

我尝试在此调用中检索它们，它确实获取了值，但并非所有属性都是

protected void UpdateGauges()
    {

        List<BoldGauge> boldGauges = (List<BoldGauge>)Session["GaugesList"];

        if (boldGauges != null)
        {
            foreach (BoldGauge gauge in boldGauges)
            {
                ArcScaleComponent scale = GetGaugeScale(gauge.Gauge, 0, 0);
                scale.BeginUpdate();
                float newValue = new Random().Next(100);
                scale.Value = newValue;
                scale.EndUpdate();
            }
        }
    }
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1 回答 1

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行为是半预期的——只是不要那样做。

在会话状态中存储不可序列化的对象通常不是一个好主意。它主要在进程内提供程序的情况下工作，并且在使用 SQL 提供程序时完全失败。

此外，当从会话状态中取出下一个请求时，存储期望页面对象存在的控件将不起作用，因为旧页面（或父控件）对象与先前的请求一起被破坏。由于其父级已销毁，该控件也可能已自行取消初始化。

于 2012-07-02T22:13:19.470 回答