Why isn't my designer property serialized in the ASPX

Question

In an attempt to create a custom data source that is supposed to be used in ASP.NET, I've created a custom data source class, a custom editor and a custom serializable class.

What I fail to understand is why it doesn't work... even though I probably have more attributes than required (I've been browsing and trying things for hours), from what I understand the PersistenceMode(PersistenceMode.InnerProperty) should have done the trick... Also, it seems to me like my code is similar to Why can't I declare sub-elements (properties) of a UserControl in a WebForm? .

The code works as follows:

[ParseChildren(true)]
[PersistChildren(true)]
public class MyDataSource : DataSourceControl
{
    // [much more irrelevant code...]

    [Browsable(true)]
    [EditorBrowsable(EditorBrowsableState.Always)]
    [PersistenceMode(PersistenceMode.InnerProperty)]
    [MergableProperty(false)]
    [TypeConverter(typeof(ExpandableObjectConverter))]
    [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]
    [Editor(typeof(Editors.ResultRequestEditor), typeof(System.Drawing.Design.UITypeEditor))]
    public ResultRequest Request { get; set; }
}

[Serializable]
[PersistChildren(true)]
[TypeConverter(typeof(ExpandableObjectConverter))]
[ParseChildren(true)]    
public class ResultRequest
{
    [Browsable(true)]
    [EditorBrowsable(EditorBrowsableState.Always)]
    public string ColumnName { get; set; }

    [Browsable(true)]
    [EditorBrowsable(EditorBrowsableState.Always)]
    public Type ColumnType { get; set; }

    [Browsable(false)]
    [EditorBrowsable(EditorBrowsableState.Always)]
    public object[] ResultTypeParameters { get; set; }
}

The custom editor seems to work: after using it, the properties in VS are updated correctly.

However, after updating something the information is not persisted in the ASPX file:

<cc1:MyDataSource ID="SearchDataSource1" runat="server" ProviderID="MyProvider1" />

What I expected was some serialization within the data source, e.g.:

<cc1:MyDataSource ID="SearchDataSource1" runat="server" ProviderID="MyProvider1">
    <Request>
        // blah
    </Request>
</cc1:MyDataSource>

Can someone please explain why this doesn't work?

Answer 1

Please take a look at my sample it's less complex so it would be easier to understand:

First parent control (in your case this would be DataSource):

[ToolboxData("<{0}:TabContainer runat=server></{0}:TabContainer>")]
[ParseChildren(ChildrenAsProperties = false)]
[PersistChildren(true)]
public class TabContainer : Panel, INamingContainer
{

    #region private properties

    List<TabItem> tabs = new List<TabItem>();

    #endregion

    [Bindable(true)]
    public event EventHandler TabClick;

    [Browsable(true)]
    [PersistenceMode(PersistenceMode.InnerProperty)]
    public List<TabItem> Tabs
    {
        get { return this.tabs; }
    }
}

Take notice I have set ChildrenAsProperties to false. And here is child definition, TabItem:

public class TabItem : Panel, IPostBackEventHandler
{


    String clientClick = String.Empty;

    public event EventHandler Click;


    [Bindable(true)]
    [Category("Appearance")]
    public string Text
    {
        get
        {
            if (ViewState["Text"] == null)
            {
                ViewState["Text"] = "";
            }
            return (string)ViewState["Text"];
        }
        set
        {
            ViewState["Text"] = value;
        }
    }
}

Now inside designer I can declare TabContainer like this:

        <cc1:TabContainer ID="TabContainer1" runat="server"
        </cc1:TabContainer>

And finally add child controls that preserve state:

        <cc1:TabContainer ID="TabContainer1" runat="server"
            OnTabClick="TabContainer_TabClick">
            <Tabs>
                <cc1:TabItem ID="Tab1" Text="Hello" runat="server" />
                <cc1:TabItem ID="Tab2" Text="World" runat="server" />
            </Tabs>
        </cc1:TabContainer>

Best regards!