如何在后面的代码中访问扩展 Panel 的自定义控件的公共属性？

Question

I am trying to create a custom control that inherits from the web control "Panel". The control itself is working as it acts like a regular Panel control, however I am only able to set the public properties on it directly in the control on the.aspx page. I have been trying to modify them in the code behind during Page_Load but that apparently is too late in the page life-cycle. When I try to do it earlier though, I get a null reference error. Is there something that I can do in the custom control itself so that it can be modified during Page_Load()?

In the ASPX, this is the control with properties set (this works fine):

<cod:ContentOnDemandPanel LocationId="4" ID="codPanelLocation" runat="server">
    <p>This is some text that is in the panel</p>
</cod:ContentOnDemandPanel>

In the code behind though (and I've tried other parts of the life-cycle). This does NOT work.

protected void Page_Load(object sender, EventArgs e)
{
    codPanelLocation.LocationId = 22;
    codPanelOfferingText.TelerikToolTipSkinName = "Black";
}

Any help is appreciated.

Here is my class (removed some stuff that probably isn't for public consumption)

namespace Home.ContentOnDemand {

 [ToolboxData("<{0}:ContentOnDemandPanel runat=server></{0}:ContentOnDemandPanel>")]


public partial class ContentOnDemandPanel : Panel, INamingContainer
{

    private ContentOnDemandDataSource _contentDataSource;
    private RadToolTip _contentEditTooltip;
    private ContentOnDemandItem _contentItem;
    private int _contentItemId;
    private bool _isEditMode;

    private bool _isSharedContent;
    private string _telerikToolTipSkinName;
    private MasterWebDatabaseDataType _mwdbDataType;
    private string _mwdbDataKeyValue;
    private int _locationId;
    private int _programId;
    private int _areaOfStudyId;
    private int _programOfferingId;

    public ContentOnDemandPanel()
    {


    }

    public override ControlCollection Controls
    {
        get
        {
            EnsureChildControls();
            return base.Controls;
        }
    }

    protected override void CreateChildControls()
    {
        if (_isEditMode == false)
        {
            this._isEditMode = CODUtilities.isUserInEditMode();
        }

        if (this._isEditMode)
        {
            Controls.Clear();

            if (_contentItemId > 0 && _contentDataSource == ContentOnDemandDataSource.CommonContent)
            {
                _contentItem = GetCommonContentItemByContentId(this._contentItemId);
                if (_contentItem != null)
                {
                    _contentEditTooltip = this.BuildRadToolTip();
                    Controls.Add(_contentEditTooltip);
                }
            }
            else
            {
                if (_contentDataSource == ContentOnDemandDataSource.MasterWeb)
                {
                    _contentItem = GetCommonContentItemForMasterWeb(_mwdbDataType);
                    _contentEditTooltip = this.BuildRadToolTip();
                    Controls.Add(_contentEditTooltip);
                }
            }
        }
    }

    public void AddButtonsToToolTip(RadToolTip tooltip, ContentOnDemandItem item)
    {
        if (item != null)
        {
            if ((item != null) && ((item.EditItemPath.Length > 5) || (item.NewItemPath.Length > 5)))
            {
                Panel pnlButtonHolder = new Panel
                {
                    CssClass = "cod-button-holder"
                };
                HyperLink editButton = this.BuildEditButton(item.EditItemPath);
                HyperLink addNewButton = this.BuildNewRecordButton(item.NewItemPath);
                if (editButton != null)
                {
                    pnlButtonHolder.Controls.Add(editButton);
                }
                if (addNewButton != null)
                {
                    pnlButtonHolder.Controls.Add(addNewButton);
                }
                tooltip.Controls.AddAt(0, pnlButtonHolder);
                this.CssClass = "cod-content-editable";
            }
            else
            {
                this.makePanelNotCOD();
            }
        }
        else
        {
            this.makePanelNotCOD();
        }
    }

    private HyperLink BuildEditButton(string editPath)
    {
        if (editPath.Length < 5)
        {
            return null;
        }
        return new HyperLink { CssClass = "cod-button-edit", Text = "Edit Record", NavigateUrl = editPath, Target = "CMSWindow" };
    }

    private HyperLink BuildNewRecordButton(string newRecordPath)
    {
        if (newRecordPath.Length < 5)
        {
            return null;
        }
        return new HyperLink { CssClass = "cod-button-new", Text = "Add New Record", NavigateUrl = newRecordPath, Target = "CMSWindow" };
    }


    private RadToolTip BuildRadToolTip()
    {
        RadToolTip tt = new RadToolTip();

        AddButtonsToToolTip(tt,_contentItem);
        return tt;
    }


    private ContentOnDemandItem GetCommonContentItemForMasterWeb(MasterWebDatabaseDataType dataType)
    {
        ContentOnDemandItem item = new ContentOnDemandItem();

        return item;
    }
    public static ContentOnDemandItem GetCommonContentItemByContentId(int contentId)
    {
        ContentOnDemandItem item = new ContentOnDemandItem();

        return item;
    }

    private void makePanelNotCOD()
    {
        this._isEditMode = false;
        this.CssClass = "";
        this._contentEditTooltip = null;
    }

    protected override void Render(HtmlTextWriter writer)
    {
        this.RenderBeginTag(writer);
        foreach (Control c in base.Controls) if (!c.Equals(_contentEditTooltip))
        c.RenderControl(writer);
        if (_contentEditTooltip != null)
        {
           this._contentEditTooltip.RenderControl(writer);
        }
        this.RenderEndTag(writer);
    }

    // Properties
    public ContentOnDemandDataSource ContentDataSource
    {
        get
        {
            return this._contentDataSource;
        }
        set
        {
            this._contentDataSource = value;
        }
    }

    public ContentOnDemandItem ContentItem
    {
        get
        {
            return this._contentItem;
        }
        set
        {
            this._contentItem = value;
        }
    }

    public bool IsEditMode
    {
        get { return _isEditMode; }
        set { _isEditMode = value; }
    }

    public int ContentItemId
    {
        get
        {
            return this._contentItemId;
        }
        set
        {
            this._contentItemId = value;
        }
    }

    public bool IsSharedContent
    {
        get
        {
            return this._isSharedContent;
        }
        set
        {
            this._isSharedContent = value;
        }
    }
    public int ProgramId
    {
        get { return _programId; }
        set { _programId = value; }
    }

    public int AreaOfStudyId
    {
        get { return _areaOfStudyId; }
        set { _areaOfStudyId = value; }
    }

    public int ProgramOfferingId
    {
        get { return _programOfferingId; }
        set { _programOfferingId = value; }
    }

    public MasterWebDatabaseDataType MwdbDataType
    {
        get { return _mwdbDataType; }
        set { _mwdbDataType = value; }
    }

    public string MwdbDataKeyValue
    {
        get { return _mwdbDataKeyValue; }
        set { _mwdbDataKeyValue = value; }
    }

    public int LocationId
    {
        get { return _locationId; }
        set { _locationId = value; }
    }

    public string TelerikToolTipSkinName
    {
        get
        {
            return this._telerikToolTipSkinName;
        }
        set
        {
            this._telerikToolTipSkinName = value;
        }
    }
}

}

Answer 1

I'd suggest, based on your code above, that you abstract your control out another level. Create an ASCX which contains a Label (to hold the "T" text) and the two hyperlinks for add/edit.

<%@ Control... %>

<div class="cod-content-editable">
    <asp:Label id="textLabel" runat="server" CssClass="Text"/>
    <div class="cod-button-holder">
        <asp:HyperLink id="editLink" runat="server" Text="Edit" ... />
    </div>
</div>

Etc., etc. and then in your code you can wire the properties directly to the controls:

public class MyControl : UserControl
{
    public string Text { get { return textLabel.Text; } set { textLabel.Text = value; } }
    public Uri EditNavigateUri { get { return editLink.NavigateUri; } set { editLink.NavigateUri = value; } }

    //...etc.
}