无法使用复合控件加载viewstate

时间：2010-10-18 12:59:50

标签： c# composite-controls failed-to-load-viewstate

我创建了一个复合控件，它根据其中一个名为“Type”的属性的值来更改其中的控件。 意图是，一旦设置了“Type”属性，它就不会在控件的生命周期内再次更改，因此由于“Type”属性的值而呈现的控件不应更改。

我已按照许多互联网帖子的建议覆盖了LoadViewState和SaveViewState方法，但我仍然收到有关“无法加载ViewState”的错误。控件将在第一次加载时正确呈现，但一旦进行任何回发，它将生成“无法加载ViewState”错误。

以下是复合控件代码的一部分：

    [Serializable]
internal enum SearchPanelControlType
{
    Label,
    DropDownList,
    TextBox
}
[Serializable]
internal class SearchGridViewStateObject<T> where T : Bll.BaseCriteria
{
    public T mySearchCriteria { get; set; }
    public SearchGridType myType { get; set; }
    public int myNumberOfChildrenPerRow { get; set; }
    public object myBaseViewState { get; set; }

    public SearchGridViewStateObject(T searchCriteria, SearchGridType type, int numberOfChildrenPerRow, object baseViewState)
    {
        mySearchCriteria = searchCriteria;
        myType = type;
        myNumberOfChildrenPerRow = numberOfChildrenPerRow;
        myBaseViewState = baseViewState;
    }
}
[Themeable(true)]
[Serializable]
public class SearchGrid<T> : CompositeControl
     where T : Bll.BaseCriteria
{
    #region Constructor
    public SearchGrid()
    {
    }
    #endregion

    #region Private Fields
    private MyCompanygridview myGridView;
    private ObjectDataSource myObjectDataSource;
    private Panel mySearchParametersPanel;
    private Button mySearchButton;
    private Button myClearSearchCriteriaButton;
    private T mySearchCriteria;
    //private SearchGridType myType = SearchGridType.Account;
    private SearchGridType myType;
    private int myNumberOfChildrenPerRow = 2;
    private MyCompanygridviewSelectionType mySelectionType = MyCompanygridviewSelectionType.None;
    private int mySelectColumnIndex = 0;
    private int myPageSize = 10;
    private int myPageIndex = 0;
    private string myGridViewCssClass;
    private string myCustomPagerButtonCssClass;
    private string myCustomPagerTextBoxCssClass;
    private string myRowCssClass;
    private string myEmptyDataRowCssClass;
    private string myPagerCssClass;
    private string mySelectedRowCssClass;
    private string myHeaderCssClass;
    private string myAlternatingRowCssClass;
    private string myDisabledRowCssClass;
    private List<Guid> myGridViewDisabledValues = new List<Guid>();
    private List<Guid> myGridViewSelectedValues = new List<Guid>();
    private GridLines myGridLines = GridLines.None;
    private string mySearchPanelButtonCssClass;
    private string mySearchPanelTextBoxCssClass;
    private string mySearchPanelDropDownListCssClass;
    private string mySearchPanelLabelCssClass;



    #endregion

    #region Public Properties
    /// <summary>
    /// Gets or sets the search criteria.
    /// </summary>
    /// <value>The search criteria.</value>
    public T SearchCriteria
    {
        get
        {
            return mySearchCriteria;
        }
        set
        {
            if (value != mySearchCriteria)
            {
                mySearchCriteria = value;
                this.ChildControlsCreated = false;
                this.EnsureChildControls();
            }
        }
    }
    /// <summary>
    /// Gets or sets the type of items that should be shown in the gridview.
    /// </summary>
    /// <summary>
    /// Gets or sets the type of items that should be shown in the gridview.
    /// </summary>
    [Category("SearchGrid"),
    Description("Gets or sets the type of items that should be shown in the grid view."),
    DefaultValue(null)]
    public SearchGridType Type
    {
        get
        {
            return myType;
        }
        set
        {
            if (value != myType)
            {
                myType = value;
                this.ChildControlsCreated = false;
                this.EnsureChildControls();
            }
        }

    }
    [DefaultValue(MyCompanygridviewSelectionType.None),
    Category("SearchGrid"),
    Description("Indicates whether to use multiselection mode, single selection mode, or no selection mode.")]
    public MyCompanygridviewSelectionType SelectionType
    {
        get
        {
            return mySelectionType;
        }
        set
        {
            mySelectionType = value;
        }
    }
    #endregion
    #region Overridden Methods
    protected override void LoadViewState(object savedState)
    {
        SearchGridViewStateObject<T> vsObject = savedState as SearchGridViewStateObject<T>;
        mySearchCriteria = vsObject.mySearchCriteria;
        myType = vsObject.myType;
        myNumberOfChildrenPerRow = vsObject.myNumberOfChildrenPerRow;

        ClearChildViewState();
        this.ChildControlsCreated = false;
        this.EnsureChildControls();

        base.LoadViewState(vsObject.myBaseViewState);
    }
    protected override object SaveViewState()
    {
        SearchGridViewStateObject<T> vsObject = new SearchGridViewStateObject<T>(mySearchCriteria, myType, myNumberOfChildrenPerRow, base.SaveViewState());
        return vsObject;
    }
    protected override void RecreateChildControls()
    {
        EnsureChildControls();
    }
    protected override void CreateChildControls()
    {
        SearchGridParser parser = SearchGridParserFactory.GetParser(this.myType);

        Controls.Clear();

        //Define the Search Parameters Panel
        mySearchParametersPanel = new Panel();
        mySearchParametersPanel.ID = "spp" + Enum.GetName(typeof(SearchGridType), this.myType);
        mySearchParametersPanel.DefaultButton = "btnSearch";
        mySearchParametersPanel.ScrollBars = ScrollBars.None;
        parser.CreateSearchPanelControls(ref mySearchParametersPanel, CreateSearchPanelStyleDictionary());


        //Define Buttons
        mySearchButton = new Button();
        mySearchButton.ID = "btnSearch";
        mySearchButton.Text = "Search";
        mySearchButton.CausesValidation = false;
        mySearchButton.UseSubmitBehavior = false;
        mySearchButton.Click += new EventHandler(mySearchButton_Click);
        if (!string.IsNullOrEmpty(mySearchPanelButtonCssClass))
        {
            mySearchButton.CssClass = mySearchPanelButtonCssClass;
        }

        myClearSearchCriteriaButton = new Button();
        myClearSearchCriteriaButton.ID = "btnClearSearchCriteria";
        myClearSearchCriteriaButton.Text = "Clear Search Criteria";
        myClearSearchCriteriaButton.CausesValidation = false;
        myClearSearchCriteriaButton.UseSubmitBehavior = false;
        myClearSearchCriteriaButton.Click += new EventHandler(myClearSearchCriteriaButton_Click);
        if (!string.IsNullOrEmpty(mySearchPanelButtonCssClass))
        {
            myClearSearchCriteriaButton.CssClass = mySearchPanelButtonCssClass;
        }

        mySearchParametersPanel.Controls.Add(mySearchButton);
        mySearchParametersPanel.Controls.Add(myClearSearchCriteriaButton);

        // Define the GridView
        myGridView = new MyCompanygridview();
        myGridView.ID = "gv" + Enum.GetName(typeof(SearchGridType), this.myType);
        myGridView.AutoGenerateColumns = false;
        myGridView.DataKeyNames = new string[] { "ID" };
        myGridView.DataSourceID = "ods" + Enum.GetName(typeof(SearchGridType), this.myType);
        myGridView.AllowSorting = true;
        myGridView.Width = new System.Web.UI.WebControls.Unit("100%");
        myGridView.AllowPaging = true;
        myGridView.EnableCustomPager = true;
        myGridView.Sorted += new EventHandler(myGridView_Sorted);
        myGridView.PageIndexChanged += new EventHandler(myGridView_PageIndexChanged);
        myGridView.PageSizeChanged += new EventHandler(myGridView_PageSizeChanged);
        myGridView.PageSizeChanging += new EventHandler(myGridView_PageSizeChanging);
        myGridView.SelectionType = this.mySelectionType;
        myGridView.SelectColumnIndex = this.mySelectColumnIndex;
        myGridView.PageSize = this.myPageSize;
        myGridView.PageIndex = this.myPageIndex;
        myGridView.CssClass = this.myGridViewCssClass;
        myGridView.CustomPagerButtonCssStyle = this.myCustomPagerButtonCssClass;
        myGridView.CustomPagerTextBoxCssStyle = this.myCustomPagerTextBoxCssClass;
        myGridView.RowStyle.CssClass = this.myRowCssClass;
        myGridView.EmptyDataRowStyle.CssClass = this.myEmptyDataRowCssClass;
        myGridView.PagerStyle.CssClass = this.myPagerCssClass;
        myGridView.SelectedRowStyle.CssClass = this.mySelectedRowCssClass;
        myGridView.HeaderStyle.CssClass = this.myHeaderCssClass;
        myGridView.AlternatingRowStyle.CssClass = this.myAlternatingRowCssClass;
        myGridView.DisabledRowCssClass = this.myDisabledRowCssClass;
        myGridView.DisabledValues = this.myGridViewDisabledValues;
        myGridView.SelectedValues = this.myGridViewSelectedValues;
        myGridView.GridLines = this.myGridLines;
        parser.CreateGridViewColumns(ref myGridView);


        // Define the object data source
        myObjectDataSource = new ObjectDataSource();
        myObjectDataSource.ID = "ods" + Enum.GetName(typeof(SearchGridType), this.myType);
        myObjectDataSource.OldValuesParameterFormatString = "original_{0}";
        myObjectDataSource.SelectMethod = "GetList";
        myObjectDataSource.SelectCountMethod = "SelectCountForGetList";
        myObjectDataSource.TypeName = "MyCompany.DCO.MyProject.Bll." + Enum.GetName(typeof(SearchGridType), this.myType) + "Manager";
        myObjectDataSource.EnablePaging = true;
        myObjectDataSource.StartRowIndexParameterName = "startRowIndex";
        myObjectDataSource.MaximumRowsParameterName = "maximumRows";
        myObjectDataSource.SortParameterName = "SortExpression";
        myObjectDataSource.Selecting += new ObjectDataSourceSelectingEventHandler(myObjectDataSource_Selecting);
        myObjectDataSource.Selected += new ObjectDataSourceStatusEventHandler(myObjectDataSource_Selected);


        // Add the defined controls
        this.Controls.Add(myObjectDataSource);
        this.Controls.Add(myGridView);
        this.Controls.Add(mySearchParametersPanel);

        parser.SetSearchPanelControls<T>(this.mySearchCriteria, ref mySearchParametersPanel);

    }

    protected override void Render(HtmlTextWriter writer)
    {
        AddAttributesToRender(writer);

        writer.RenderBeginTag(HtmlTextWriterTag.Div);

        mySearchParametersPanel.RenderControl(writer);
        writer.RenderBeginTag(HtmlTextWriterTag.Br);
        writer.RenderEndTag();

        myGridView.RenderControl(writer);
        writer.RenderBeginTag(HtmlTextWriterTag.Br);
        writer.RenderEndTag();

        myObjectDataSource.RenderControl(writer);
        writer.RenderEndTag();
    }
    #endregion

}

以下是创建自定义控件的“解析器”文件的代码：

    class SearchGridParser_ApplicationFunction : SearchGridParser
{
    internal override void CreateGridViewColumns(ref MyCompanygridview myGridView)
    {
        // Link Column
        HyperLinkField linkColumn = new HyperLinkField();
        linkColumn.Text = "Edit";
        linkColumn.HeaderText = "ID";
        linkColumn.DataNavigateUrlFields = new string[] { "ID" };
        linkColumn.DataNavigateUrlFormatString = "~/AddEdit/ApplicationFunction/default.aspx?Action=Edit&ID={0}";
        myGridView.Columns.Add(linkColumn);

        // Name Column
        BoundField nameColumn = new BoundField();
        nameColumn.DataField = "Name";
        nameColumn.HeaderText = "Name";
        nameColumn.SortExpression = "Name";
        myGridView.Columns.Add(nameColumn);

        // Description Column
        BoundField descriptionColumn = new BoundField();
        descriptionColumn.DataField = "Description";
        descriptionColumn.HeaderText = "Description";
        descriptionColumn.SortExpression = "Description";
        myGridView.Columns.Add(descriptionColumn);

        // Business Criticality Column
        TemplateField businessCriticalityColumn = new TemplateField();
        businessCriticalityColumn.SortExpression = "BusinessCriticality";
        businessCriticalityColumn.HeaderText = "Criticality";
        businessCriticalityColumn.ItemTemplate = new LabelColumnGridViewTemplate(ListItemType.Item, "BusinessCriticality", "Name");
        myGridView.Columns.Add(businessCriticalityColumn);

        // Disabled Column
        CheckBoxField disabledColumn = new CheckBoxField();
        disabledColumn.DataField = "DisabledFlg";
        disabledColumn.HeaderText = "Disabled";
        disabledColumn.SortExpression = "DisabledFlg";
        myGridView.Columns.Add(disabledColumn);

        // Agencies Column
        TemplateField agenciesColumn = new TemplateField();
        agenciesColumn.HeaderText = "Agencies";
        agenciesColumn.ItemTemplate = new ChildObjectsGridViewTemplate(ListItemType.Item, 2, "Agencies", "Agency.Abbreviation");
        myGridView.Columns.Add(agenciesColumn);

        // Applications Column
        TemplateField applicationsColumn = new TemplateField();
        applicationsColumn.HeaderText = "Applications";
        applicationsColumn.ItemTemplate = new ChildObjectsGridViewTemplate(ListItemType.Item, 2, "Applications", "Application.Name");
        myGridView.Columns.Add(applicationsColumn);
    }

    internal override void CreateSearchPanelControls(ref Panel myPanel, Dictionary<SearchPanelControlType, string> myStyleDictionary)
    {
        if (myStyleDictionary == null)
        {
            myStyleDictionary = new Dictionary<SearchPanelControlType, string>();
        }

        // Title
        Literal myTitleStart = new Literal();
        myTitleStart.Text = "<h4>";

        Label myTitle = new Label();
        myTitle.Text = "Application Function:";
        myTitle.ID = "lblTitle";

        Literal myTitleEnd = new Literal();
        myTitleEnd.Text = "</h4>";



        // Begin Table
        Table myTable = new Table();
        myTable.ID = "myTable";

        // Create First Row
        TableRow myTableRow1 = new TableRow();
        myTableRow1.ID = "myTableRow1";

        // Search by Name
        TableCell myNameLabelTableCell = new TableCell();
        myNameLabelTableCell.ID = "myNameLabelTableCell";
        Label myNameLabel = new Label();
        myNameLabel.ID = "lblName";
        myNameLabel.Text = "Name:";
        myNameLabel.AssociatedControlID = "txtName";
        if (myStyleDictionary.ContainsKey(SearchPanelControlType.Label))
        {
            myNameLabel.CssClass = myStyleDictionary[SearchPanelControlType.Label];
        }
        myNameLabelTableCell.Controls.Add(myNameLabel);
        myTableRow1.Cells.Add(myNameLabelTableCell);

        TableCell myNameUserInputTableCell = new TableCell();
        myNameUserInputTableCell.ID = "myNameUserInputTableCell";
        TextBox myNameTextBox = new TextBox();
        myNameTextBox.ID = "txtName";
        if (myStyleDictionary.ContainsKey(SearchPanelControlType.TextBox))
        {
            myNameTextBox.CssClass = myStyleDictionary[SearchPanelControlType.TextBox];
        }
        myNameUserInputTableCell.Controls.Add(myNameTextBox);
        myTableRow1.Cells.Add(myNameUserInputTableCell);


        // Search by Agency
        TableCell myAgencyLabelTableCell = new TableCell();
        myAgencyLabelTableCell.ID = "myAgencyLabelTableCell";
        Label myAgencyLabel = new Label();
        myAgencyLabel.ID = "lblAgency";
        myAgencyLabel.Text = "Agency:";
        myAgencyLabel.AssociatedControlID = "ddlAgency";
        if (myStyleDictionary.ContainsKey(SearchPanelControlType.Label))
        {
            myAgencyLabel.CssClass = myStyleDictionary[SearchPanelControlType.Label];
        }
        myAgencyLabelTableCell.Controls.Add(myAgencyLabel);
        myTableRow1.Cells.Add(myAgencyLabelTableCell);

        TableCell myAgencyUserInputTableCell = new TableCell();
        myAgencyUserInputTableCell.ID = "myAgencyUserInputTableCell";
        DropDownList<AgencyCriteria> myAgencyDDL = new DropDownList<AgencyCriteria>();
        myAgencyDDL.Type = DropDownListType.Agency;
        myAgencyDDL.ID = "ddlAgency";
        if (myStyleDictionary.ContainsKey(SearchPanelControlType.DropDownList))
        {
            myAgencyDDL.CssClass = myStyleDictionary[SearchPanelControlType.DropDownList];
        }
        myAgencyDDL.DisplayDisabled = true;
        myAgencyDDL.EnableAnyOption = true;
        myAgencyDDL.DataBind();
        myAgencyUserInputTableCell.Controls.Add(myAgencyDDL);
        myTableRow1.Cells.Add(myAgencyUserInputTableCell);


        myTable.Rows.Add(myTableRow1);

        // Create Second row
        TableRow myTableRow2 = new TableRow();
        myTableRow2.ID = "myTableRow2";


        // Search by BusinessCriticality
        TableCell myBusinessCriticalityLabelTableCell = new TableCell();
        myBusinessCriticalityLabelTableCell.ID = "myBusinessCriticalityLabelTableCell";
        Label myBusinessCriticalityLabel = new Label();
        myBusinessCriticalityLabel.ID = "lblBusinessCriticality";
        myBusinessCriticalityLabel.Text = "Criticality:";
        myBusinessCriticalityLabel.AssociatedControlID = "ddlBusinessCriticality";
        if (myStyleDictionary.ContainsKey(SearchPanelControlType.Label))
        {
            myBusinessCriticalityLabel.CssClass = myStyleDictionary[SearchPanelControlType.Label];
        }
        myBusinessCriticalityLabelTableCell.Controls.Add(myBusinessCriticalityLabel);
        myTableRow2.Cells.Add(myBusinessCriticalityLabelTableCell);

        TableCell myBusinessCriticalityUserInputTableCell = new TableCell();
        myBusinessCriticalityUserInputTableCell.ID = "myBusinessCriticalityUserInputTableCell";
        DropDownList<LookupCodeCriteria> myBusinessCriticalityDDL = new DropDownList<LookupCodeCriteria>();
        myBusinessCriticalityDDL.Type = DropDownListType.LookupCode;
        myBusinessCriticalityDDL.ID = "ddlBusinessCriticality";
        if (myStyleDictionary.ContainsKey(SearchPanelControlType.DropDownList))
        {
            myBusinessCriticalityDDL.CssClass = myStyleDictionary[SearchPanelControlType.DropDownList];
        }
        myBusinessCriticalityDDL.DisplayDisabled = true;
        myBusinessCriticalityDDL.EnableAnyOption = true;
        LookupCodeCriteria myBusinessCriticalityCriteria = new LookupCodeCriteria();
        myBusinessCriticalityCriteria.Type = LookupCodeType.BusinessCriticality;
        myBusinessCriticalityDDL.OtherCriteria = myBusinessCriticalityCriteria;
        myBusinessCriticalityDDL.DataBind();
        myBusinessCriticalityUserInputTableCell.Controls.Add(myBusinessCriticalityDDL);
        myTableRow2.Cells.Add(myBusinessCriticalityUserInputTableCell);

        // Search by DisabledFlg
        TableCell myDisabledFlgLabelTableCell = new TableCell();
        myDisabledFlgLabelTableCell.ID = "myDisabledFlgLabelTableCell";
        Label myDisabledFlgLabel = new Label();
        myDisabledFlgLabel.ID = "lblDisabledFlg";
        myDisabledFlgLabel.Text = "Disabled:";
        myDisabledFlgLabel.AssociatedControlID = "ddlDisabledFlg";
        if (myStyleDictionary.ContainsKey(SearchPanelControlType.Label))
        {
            myDisabledFlgLabel.CssClass = myStyleDictionary[SearchPanelControlType.Label];
        }
        myDisabledFlgLabelTableCell.Controls.Add(myDisabledFlgLabel);
        myTableRow2.Cells.Add(myDisabledFlgLabelTableCell);

        TableCell myDisabledFlgUserInputTableCell = new TableCell();
        myDisabledFlgUserInputTableCell.ID = "myDisabledFlgUserInputTableCell";
        YesNoAnyDropDownList myDisabledFlgDDL = new YesNoAnyDropDownList();
        myDisabledFlgDDL.ID = "ddlDisabledFlg";
        if (myStyleDictionary.ContainsKey(SearchPanelControlType.DropDownList))
        {
            myDisabledFlgDDL.CssClass = myStyleDictionary[SearchPanelControlType.DropDownList];
        }
        myDisabledFlgDDL.DataBind();
        myDisabledFlgUserInputTableCell.Controls.Add(myDisabledFlgDDL);
        myTableRow2.Cells.Add(myDisabledFlgUserInputTableCell);

        myTable.Rows.Add(myTableRow2);


        myPanel.Controls.Add(myTitleStart);
        myPanel.Controls.Add(myTitle);
        myPanel.Controls.Add(myTitleEnd);
        myPanel.Controls.Add(myTable);
    }

    internal override void FillSearchCriteria<T>(T myCriteria, ref Panel myPanel)
    {
        ApplicationFunctionCriteria derivedCriteria = new ApplicationFunctionCriteria();
        if (myCriteria != null)
        {
            derivedCriteria = myCriteria as ApplicationFunctionCriteria;
        }

        // Name
        TextBox myNameTextBox = (TextBox)myPanel.FindControl("myTable").FindControl("myTableRow1").FindControl("myNameUserInputTableCell").FindControl("txtName");
        if (!string.IsNullOrEmpty(myNameTextBox.Text.Trim()))
        {
            derivedCriteria.Name = myNameTextBox.Text.Trim();
        }
        else
        {
            derivedCriteria.Name = string.Empty;
        }

        // AgencyID
        DropDownList<AgencyCriteria> myAgencyDDL = (DropDownList<AgencyCriteria>)myPanel.FindControl("myTable").FindControl("myTableRow1").FindControl("myAgencyUserInputTableCell").FindControl("ddlAgency");
        Guid myAgencyID;
        if (myAgencyDDL.SelectedValue.TryParseGuid(out myAgencyID))
        {
            derivedCriteria.AgencyID = myAgencyID;
        }
        else
        {
            derivedCriteria.AgencyID = null;
        }

        // BusinessCriticalityID
        DropDownList<LookupCodeCriteria> myBusinessCriticalityDDL = (DropDownList<LookupCodeCriteria>)myPanel.FindControl("myTable").FindControl("myTableRow2").FindControl("myBusinessCriticalityUserInputTableCell").FindControl("ddlBusinessCriticality");
        Guid myBusinessCriticalityID;
        if (myBusinessCriticalityDDL.SelectedValue.TryParseGuid(out myBusinessCriticalityID))
        {
            derivedCriteria.BusinessCriticalityID = myBusinessCriticalityID;
        }
        else
        {
            derivedCriteria.BusinessCriticalityID = null;
        }

        // DisabledFlg
        YesNoAnyDropDownList myDisabledFlgDDL = (YesNoAnyDropDownList)myPanel.FindControl("myTable").FindControl("myTableRow2").FindControl("myDisabledFlgUserInputTableCell").FindControl("ddlDisabledFlg");
        bool myDisabledFlg;
        if (bool.TryParse(myDisabledFlgDDL.SelectedValue, out myDisabledFlg))
        {
            derivedCriteria.DisabledFlg = myDisabledFlg;
        }
        else
        {
            derivedCriteria.DisabledFlg = null;
        }

    }

    internal override void SetSearchPanelControls<T>(T myCriteria, ref Panel myPanel)
    {
        ApplicationFunctionCriteria derivedCriteria = new ApplicationFunctionCriteria();
        if (myCriteria != null)
        {
            derivedCriteria = myCriteria as ApplicationFunctionCriteria;
        }

        // Name
        TextBox myNameTextBox = (TextBox)myPanel.FindControl("myTable").FindControl("myTableRow1").FindControl("myNameUserInputTableCell").FindControl("txtName");
        myNameTextBox.Text = derivedCriteria.Name;

        // AgencyID
        DropDownList<AgencyCriteria> myAgencyDDL = (DropDownList<AgencyCriteria>)myPanel.FindControl("myTable").FindControl("myTableRow1").FindControl("myAgencyUserInputTableCell").FindControl("ddlAgency");
        if (derivedCriteria.AgencyID.HasValue)
        {
            myAgencyDDL.SelectedValue = derivedCriteria.AgencyID.ToString();
        }
        else
        {
            myAgencyDDL.SelectedValue = "0";
        }

        // BusinessCriticalityID
        DropDownList<LookupCodeCriteria> myBusinessCriticalityDDL = (DropDownList<LookupCodeCriteria>)myPanel.FindControl("myTable").FindControl("myTableRow2").FindControl("myBusinessCriticalityUserInputTableCell").FindControl("ddlBusinessCriticality");
        if (derivedCriteria.BusinessCriticalityID.HasValue)
        {
            myBusinessCriticalityDDL.SelectedValue = derivedCriteria.BusinessCriticalityID.ToString();
        }
        else
        {
            myBusinessCriticalityDDL.SelectedValue = "0";
        }

        // DisabledFlg
        YesNoAnyDropDownList myDisabledFlgDDL = (YesNoAnyDropDownList)myPanel.FindControl("myTable").FindControl("myTableRow2").FindControl("myDisabledFlgUserInputTableCell").FindControl("ddlDisabledFlg");
        if (derivedCriteria.DisabledFlg.HasValue)
        {
            myDisabledFlgDDL.SelectedValue = derivedCriteria.DisabledFlg.ToString();
        }
        else
        {
            myDisabledFlgDDL.SelectedValue = "any";
        }

    }
}

以下是我用来测试控件的aspx页面上的代码：

    <html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>
    </div>
    </form>
</body>
</html>

代码隐藏：

public partial class test : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        CustomWebControls.SearchGrid<AccountCriteria> myAppFuncGrid = new      MyCompany.DCO.MyProject.CustomWebControls.SearchGrid<AccountCriteria>();
        myAppFuncGrid.Type = MyCompany.DCO.MyProject.CustomWebControls.SearchGridType.Account;
        myAppFuncGrid.SelectionType = MyCompany.DCO.Library.WebControls.MyCompanygridviewSelectionType.Multiple;
        myAppFuncGrid.PageSize = 3;
        PlaceHolder1.Controls.Add(myAppFuncGrid);
    }
}

我已经尝试过只将控件放在if（！Page.IsPostBack）中，但是它甚至根本没有在Postback上显示控件。我做错了什么？

更新： 所以我把它添加到复合控件中：

protected override void OnInit(EventArgs e) 
{ 
 this.CreateChildControls(); base.OnInit(e); 
}

现在我不再收到“无法加载viewstate”错误，但似乎子控件的视图状态不会在回发中保存。我的复合控件中的一个控件是启用了分页的gridview，当单击下一页时，它将转到第2页，但从不转到第3页或第4页。但它会毫无问题地进入“最后一页”，“第一页”。但是下一页和上一页不能正常工作，但它也不会引发错误。想法？

1 个答案:

答案 0 :(得分：0)

将控件动态添加到页面时，请尝试重写OnInit或CreateChildControls并在其中执行。

Viewstate在预加载阶段加载，因此无法为控件加载viewstate，因为它们尚不存在...

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