Why is this String remaining null?

Question

The controls on my WebPart are not being created because the condition:

if (this.dpsvisWebPart != null && this.dpsvisWebPart.CustomTitleProp != null)

...fails due to CustomTitleProp being null. Yet it is declared in the WebPart's constructor and should not be null.

Here is the code:

namespace DirectPaymentSectionsWebPart.DPSVisualWebPart
{
    [ToolboxItemAttribute(false)]
    public class DPSVisualWebPart : WebPart
    {
        // Text
        [WebBrowsable(true),
        Category("Financial Affairs Forms"),
        Personalizable(PersonalizationScope.Shared),
        WebDisplayName("WebPart Title Text")]        
        public string CustomTitleProp { get; set; }

        // Checkboxes
        [WebBrowsable(true),
        Category("Financial Affairs Forms"),
        Personalizable(PersonalizationScope.Shared),
        WebDisplayName("Generate Section1")]
        public bool CheckboxGenSection1 { get; set; }

            . . .

// Visual Studio might automatically update this path when you change the Visual Web Part project item.
        private const string _ascxPath = @"~/_CONTROLTEMPLATES/DirectPaymentSectionsWebPart/DPSVisualWebPart/DPSVisualWebPartUserControl.ascx";
        . . .

        protected override void CreateChildControls()
        {
            //base.CreateChildControls(); // added this 5/28/2015 <= commented out, because it is being called over and over again
            DPSVisualWebPartUserControl control = Page.LoadControl(_ascxPath) as DPSVisualWebPartUserControl;
            //DPSVisualWebPartUserControl control = Page.LoadControl(siteUrl) as DPSVisualWebPartUserControl;
            if (control != null)
            {
                control.dpsvisWebPart = this;
            }
            Controls.Add(control);
        }
    } // class DPSVisualWebPart

So why might it be that CustomTitleProp is null at the previously noted juncture? Here that code is with more context:

public partial class DPSVisualWebPartUserControl : UserControl
{
    public DPSVisualWebPart dpsvisWebPart { get; set; }
    System.Web.UI.ScriptManager scriptMgr;

    . . .

    protected void Page_Load(object sender, EventArgs e)
    {
        base.OnPreRender(e);

        if (System.Web.UI.ScriptManager.GetCurrent(this.Page) == null)
        {
            scriptMgr = new System.Web.UI.ScriptManager();
            scriptMgr.EnablePartialRendering = true;
            this.Controls.AddAt(0, scriptMgr);
        }

        if (this.dpsvisWebPart != null && this.dpsvisWebPart.CustomTitleProp != null)
        {
            lbl_Title.Text = String.Format("<h1>{0}</h1>", this.dpsvisWebPart.CustomTitleProp.ToString());
        . . .

UPDATE

Under the heading of "Adventures in Folder Diffing" comes this:

The legacy project contains a file named FileListAbsolute.txt with this content:

C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\bin\Debug\DirectPaymentSectionsWebPart.dll
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\bin\Debug\DirectPaymentSectionsWebPart.pdb
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\bin\Debug\Microsoft.Sharepoint.Sandbox.dll
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\obj\Debug\ResolveAssemblyReference.cache
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\obj\Debug\DirectPaymentSectionsWebPart.dll
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\obj\Debug\DirectPaymentSectionsWebPart.pdb

The new project contains a file of the same name with this content:

C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\bin\Debug\DirectPaymentSectionsWebPart.dll
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\bin\Debug\DirectPaymentSectionsWebPart.pdb
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\bin\Debug\Microsoft.Sharepoint.Sandbox.dll
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\obj\Debug\ResolveAssemblyReference.cache
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\obj\Debug\DirectPaymentSectionsWebPart.dll
C:\Projects\DirectPaymentSectionsWebPart\DirectPaymentSectionsWebPart\obj\Debug\DirectPaymentSectionsWebPart.pdb
C:\Projects\DirectPaymentWebForm\DirectPaymentSectionsWebPart\obj\Debug\ResolveAssemblyReference.cache
C:\Projects\DirectPaymentWebForm\DirectPaymentSectionsWebPart\obj\Debug\DirectPaymentSectionsWebPart.dll
C:\Projects\DirectPaymentWebForm\DirectPaymentSectionsWebPart\bin\Debug\DirectPaymentSectionsWebPart.dll
C:\Projects\DirectPaymentWebForm\DirectPaymentSectionsWebPart\bin\Debug\DirectPaymentSectionsWebPart.pdb
C:\Projects\DirectPaymentWebForm\DirectPaymentSectionsWebPart\bin\Debug\Microsoft.Sharepoint.Sandbox.dll
C:\Projects\DirectPaymentWebForm\DirectPaymentSectionsWebPart\obj\Debug\DirectPaymentSectionsWebPart.pdb

So I wonder: should I remove the first six entries from the new project's file, which reference the legacy project? Or will doing so cause Pearl Harbor III to erupt?

UPDATE 2

I tried this:

...and it turns out that there already is a ScriptManager by this point (Page_Load()) event, and that it already has EnablePartialRendering set, and so this code is moot. The question still is, though, why in Hec Ramsay is CustomTitle null here:

if (this.dpsvisWebPart != null && this.dpsvisWebPart.CustomTitleProp != null)

...which comes right after the (about-to-be-removed-because-its-moot) code in the Page_Load() event?

UPDATE 3

Alright (or is it "all right"?) - which is, at any rate, a funny thing to say when obviously not everything is all right, but then again, it's Friday, so it's okay...anyway:

I wondered: "maybe 'CustomTitleProp' is null because the Web Editor (after all, that's where CustomTitleProp lives) is not being created/rendered. And sure enough, when I went to "Edit Web Part" the Web Part Editor wouldn't even display, and I again got blasted with the red-hot, reeking-breath Sharepoint mother-in-law thus:

"Web Part Error: A Web Part or Web Form Control on this Page cannot be displayed or imported. The type DirectPaymentSectionsWebPart.DPSVisualWebPart.DPSVisualWebPart, DirectPaymentSectionsWebPart, Version=1.0.0.0, Culture=neutral, PublicKeyToken=bbf47e850237632c could not be found or it is not registered as safe."

Alas and anon, it is back to the coding board again! For forsooth, why is my WebPartEditor not displaying?

(sorry, I've been reading "A Connecticut Yankee in King Arthur's Court" of late).

Answer 1

Once I entered a value in the Web Part Editor for this, the problem went away. But the question still remains, how to prevent this prior to adding a value via the Web Part Editor? I see no way to give this a default value; I assume even a space (" ") would do the trick...

Could I do something like:

[WebBrowsable(true),
Category("Financial Affairs Forms"),
Personalizable(PersonalizationScope.Shared),
WebDisplayName("WebPart Title Text")]        
public string CustomTitleProp { call a custom method to return a space or something; set; }

?

Answer 2

I think you have to just register your dll as safe in Web.config.