System.NullReferenceException: 'Object reference not set to an instance of an object.' page was null

Question

I'm traying to test this method that checks for specific tag footer to show.

here is the function:

    public void CheckForOrderOfFooterTags(PdfDocument pdfDoc, out TagTreePointer autoP, out TagTreePointer posBackup, out TagTreeInfo p)
    {
        //  the following logic takes care of changing the order of the footer tags
        //  so that footers appear in the proper order in the tag tree structure
        autoP =pdfDoc.GetTagStructureContext().GetAutoTaggingPointer();
        posBackup =new TagTreePointer(autoP);
        PagesTag.TryGetValue(PageNumber, out p);
        if (p?.TagTreePointer != null)
        {
            //  Make sure that content that will be tagged is placed in tag structure specifically where we need it.
            int indexInParentKidsList = p.TagTreePointer.GetIndexInParentKidsList();
            autoP.MoveToPointer(p.TagTreePointer).MoveToParent();
            //  setting new index only works on taggable items
            if (p.Tagged)
            {
                autoP.SetNextNewKidIndex(indexInParentKidsList + 1);
            }
        }
    }

and this is the test:

    public void Check_For_Specific_Tag_Footer_To_Show_Successfully_Called()
    {
        var ir = new TestIllustrationReport().Report;
        var reportProperties = new TestDocument().ReportProperties;
        var sec = new FooterSection(new ProductContent(ir));
        sec.Build();
        Dictionary<int, TagTreeInfo> dict = new Dictionary<int, TagTreeInfo>();
        reportProperties.FooterTag=dict;
        FooterEventHandler footerEvent = new FooterEventHandler(sec, reportProperties);

        // Must have write permissions to the path folder
        var path = System.IO.Path.GetTempPath();
        var fileName = System.IO.Path.ChangeExtension("Test", ".pdf");
        var com = System.IO.Path.Combine(path, fileName);

        // pdf
        PdfWriter writer = new PdfWriter(com);
        PdfDocument pdf = new PdfDocument(writer);
        Event headerEvent= new PdfDocumentEvent("pdf", pdf);
        PdfDocumentEvent docEvent = (PdfDocumentEvent)headerEvent;
        iText.Layout.Document document = new iText.Layout.Document(pdf);
        pdf.GetCatalog().SetLang(new PdfString("en-US"));

        // Header and Paragraph
        Paragraph header = new Paragraph(TestData.Header)
     .SetTextAlignment(TextAlignment.CENTER)
     .SetFontSize(20);

        document.Add(header);

        pdf.SetTagged();
        pdf.GetCatalog().SetViewerPreferences(new PdfViewerPreferences().SetDisplayDocTitle(true));

        PdfDocumentInfo info = pdf.GetDocumentInfo();
        info.SetTitle("Testing tags");

        Paragraph p = new Paragraph();
        p.Add("The quick brown ");
        PdfPage page = docEvent.GetPage();

        // Rectangle and canvas
        Rectangle rectangle = new Rectangle(
    pdf.GetDefaultPageSize().GetX() + document.GetLeftMargin(),
    pdf.GetDefaultPageSize().GetTop() - 80,
    page.GetPageSize().GetWidth() - document.GetLeftMargin() - document.GetRightMargin(),
    50);
        Div canvas = new Div().SetFixedPosition(pdf.GetPageNumber(page), rectangle.GetLeft(), rectangle.GetBottom(), rectangle.GetWidth());
        Paragraph pFooter = new Paragraph(TestData.Paragraph);
        pFooter.GetAccessibilityProperties().SetRole("H");
        canvas.Add(pFooter);
        document.Add(canvas);

        // Don't close document itself! It would close the PdfDocument!
        document.GetRenderer().Close();

        var pPointer = new TagTreePointer(pdf);
        var pInfo = new TagTreeInfo { Tagged = true };
        // Act 
        footerEvent.CheckForOrderOfFooterTags(pdf, out pPointer, out pPointer, out pInfo);
        document.Close();

        // Assert 
        Assert.NotNull(pdf);

    }

For this test, I needed to create the pdf, set and build the footer section. I added the header to the pdf and the "footer test", I also set the document to be tagged.

I don't know why I always get the page is null if I'm adding a header and a paragraph to it.

Where is page null? `PdfPage page = docEvent.GetPage();` here GetPage() returns null? I don't know this library: why are you fetching the page from the header event and not the PdfDocument? — Rup, Nov 04 '22 at 13:04
Does this answer your question? [What is a NullReferenceException, and how do I fix it?](https://stackoverflow.com/questions/4660142/what-is-a-nullreferenceexception-and-how-do-i-fix-it) — Klaus Gütter, Nov 04 '22 at 14:00

score 1 · Answer 1 · edited Mar 22 '23 at 01:54

solution for itext7 itext pdf document System.NullReferenceException: 'Object reference not set to an instance of an object.'

Finally, I found the solution from Westley Bennett:

Apparently iText has some internal errors/exceptions that they are just sort of "skipping" and "pushing past", because I realized by accident that I had "Enable Just My Code" in Visual Studios disabled, and so my system was trying to debug iText7's code as well as mine. The moment that I re-enabled it in my Visual Studio settings (Tools > Options > Debugging > General > Enable Just My Code checkbox), the problem magically went away.

Settings in Visual Studio

So I spent four hours trying to troubleshoot a problem that was in THEIR code, but they apparently found some way to work around and push through the method anyways even on a null reference failure.

My convert to PDF function is now working just fine.

System.NullReferenceException: 'Object reference not set to an instance of an object.' page was null

1 Answers1