如何在使用C＃動態創建時保留StateManagedCollection？

Question

people〜

我正在使用C＃創建一個自定義的gridview繼承自CompositeDataBoundControl。 我有一個公共屬性，名爲「Columns」，如下所示。

private FixedGridColumnCollection _columnCollection = null; 
    /// <summary> 
    /// FixedGrid's columns 
    /// </summary> 
    [Category("BANANA Framework")] 
    [Description("Gets or sets FixedGrid's columns")] 
    [Editor(typeof(FixedGridColumnCollectionEditor), typeof(UITypeEditor))] 
    [PersistenceMode(PersistenceMode.InnerDefaultProperty)] 
    [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)] 
    [ReadOnly(true)] 
    public FixedGridColumnCollection Columns 
    { 
     get 
     { 
      if (this._columnCollection == null) 
       this._columnCollection = new FixedGridColumnCollection(); 
      if (base.IsTrackingViewState) 
      { 
       ((IStateManager)(this._columnCollection)).TrackViewState(); 
      } 
      return _columnCollection; 
     } 
    } 

既然FixedGridColumnCollection類在下面。

[TypeConverter(typeof(FixedGridColumnConverter))] 
public class FixedGridColumnCollection : StateManagedCollection 
{ 
    // Fields 
    #region Type : FixedGrid's column types 
    /// <summary> 
    /// FixedGrid's column types 
    /// </summary> 
    private static readonly Type[] _knownTypes = new Type[] 
    { 
     typeof(BANANA.Web.Controls.BoundDataField) 
     , typeof(BANANA.Web.Controls.TextBoxField) 
     , typeof(BANANA.Web.Controls.HyperLinkField) 
     , typeof(BANANA.Web.Controls.LinkButtonField) 
     , typeof(BANANA.Web.Controls.CheckBoxField) 
     , typeof(BANANA.Web.Controls.DropDownListField) 
     , typeof(BANANA.Web.Controls.RadioButtonField) 
     , typeof(BANANA.Web.Controls.DatePickerField) 
     , typeof(BANANA.Web.Controls.CodeHelperField) 
     , typeof(BANANA.Web.Controls.TemplateField) 
    }; 
    #endregion 

    // Properties 
    #region BoundFieldBase 
    public BaseDataField this[int index] 
    { 
     get { return (BaseDataField)((IList)this)[index]; } 
    } 
    #endregion 

    #region Type 
    protected override Type[] GetKnownTypes() 
    { 
     return _knownTypes; 
    } 
    #endregion 

    // Methods 
    #region Add 
    public int Add(BaseDataField item) 
    { 
     return ((IList)this).Add(item); 
    } 
    #endregion 

    #region Remove 
    public void Remove(BaseDataField item) 
    { 
     ((IList)this).Remove(item); 
    } 
    #endregion 

    #region SetDirtyObject 
    protected override void SetDirtyObject(object o) 
    { 
     ((BaseDataField)o).SetDirty(); 
    } 
    #endregion 

    #region CreateKnownType 
    protected override object CreateKnownType(int index) 
    { 
     switch (index) 
     { 
      case 0: 
       return new BANANA.Web.Controls.BoundDataField(); 
      case 1: 
       return new BANANA.Web.Controls.TextBoxField(); 
      case 2: 
       return new BANANA.Web.Controls.HyperLinkField(); 
      case 3: 
       return new BANANA.Web.Controls.LinkButtonField(); 
      case 4: 
       return new BANANA.Web.Controls.CheckBoxField(); 
      case 5: 
       return new BANANA.Web.Controls.DropDownListField(); 
      case 6: 
       return new BANANA.Web.Controls.RadioButtonField(); 
      case 7: 
       return new BANANA.Web.Controls.DatePickerField(); 
      case 8: 
       return new BANANA.Web.Controls.CodeHelperField(); 
      case 9: 
       return new BANANA.Web.Controls.TemplateField(); 
      default: 
       throw new Exception("Does not support this kind of filed in FixedGrid."); 
     } 
    } 
    #endregion 

    #region OnValidate 
    protected override void OnValidate(object o) 
    { 
     base.OnValidate(o); 
     if (!(o is BaseDataField)) 
      throw new ArgumentException("It must be value of BaseDataField.", "value"); 
    } 
    #endregion 
} 

當靜態聲明列時，它對頁面正常工作。 但是，當我動態創建列時，像下面一樣回發時，我會丟失所有列。

protected void Page_Load(object sender, EventArgs e) 
    { 
     if (!IsPostBack) 
     { 
      BANANA.Web.Controls.BoundDataField field = null; 
      BANANA.Web.Controls.TemplateField tField = null; 

      tField = new BANANA.Web.Controls.TemplateField(); 
      tField.ItemTemplate = new GridViewRadioButtonTemplate("APPSTATUS", _strRadioButtonID); 
      tField.ID = "APPSTATUS"; 
      tField.Width = 30; 
      tField.HorizontalAlignment = BANANA.Web.Controls.HorizontalAlignment.Center; 
      this.FixedGrid1.Columns.Add(tField); 

      FixedGrid1.DataSource = _dt; 
      FixedGrid1.DataBind(); 
     } 
    } 

我的代碼有什麼問題？ 有人可以給我任何線索嗎？

Answer 1

如果您在頁面初始化中加載列，那麼列應該能夠足夠早地提取視圖狀態，並且每次都應該顯示所有列。您的數據只能在首頁請求中加載。像這樣：

protected void Page_Init(object sender, EventArgs e) 
{ 
    BANANA.Web.Controls.BoundDataField field = null; 
    BANANA.Web.Controls.TemplateField tField = null; 

    tField = new BANANA.Web.Controls.TemplateField(); 
    tField.ItemTemplate = new GridViewRadioButtonTemplate("APPSTATUS", _strRadioButtonID); 
    tField.ID = "APPSTATUS"; 
    tField.Width = 30; 
    tField.HorizontalAlignment = BANANA.Web.Controls.HorizontalAlignment.Center; 
    this.FixedGrid1.Columns.Add(tField); 
} 

protected void Page_Load(object sender, EventArgs e) 
{ 
    if (!IsPostBack) 
    { 
     FixedGrid1.DataSource = _dt; 
     FixedGrid1.DataBind(); 
    } 
}