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c# - iTextSharp HTMLWorker.ParseToList() throws NullReferenceException

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c# - iTextSharp HTMLWorker.ParseToList() throws NullReferenceException

I am using iTextSharp v.4 to merge a whole bunch of html files. It was working fine until I needed to upgrade to v.5 of iTextSharp.

The problem comes when I pass a streamreader (reading the content of the html file) into the HTMLWorker object's ParseToList method. It throws a null reference exception. On debugging it I can access the streamReader and can confirm that the correct content of the file is read.

Here is the code:

List<IElement> objects;
try
{
    objects = HTMLWorker.ParseToList(new StringReader(htmlString), null);
}
catch (Exception e)
{
    htmlString = "<html><head></head><body><br/><br/><h2 style='color:#FF0000'>ERROR READING FILE!</h2><h3>File Excluded From Stitched Document!</h3><br/><br/><p>There was an error while trying to read the following file:</p><p><span style='color:#FF0000'>" + fileName + "</span></p></body></html>";
    objects = HTMLWorker.ParseToList(new StringReader(htmlString), null);
}

In the catch block you will see that I then use practically the same code to add text to the pdf to say that there was a problem. This code works fine. This of course makes me think that the problem lies in the content of the original html string, so here is the content of the string as it is immediately before being passed into the parser:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
    <meta http-equiv="Pragma" content="no-cache" />
    <meta http-equiv="cache-control" content="no-cache" />
</head>
<body style="font-family: Arial, Helvetica, sans-serif; font-size: 1em; margin: 0;
    padding: 0;">
    <div style="font-size: 1em; line-height: 1.25em; width: 190mm;">
        <h1 style="font-size: 1.5em; font-weight: bold; margin: 0 0 1.5em 0; text-align: center;">
            Advice Item 1</h1>
        <table border="0" style="width: 190mm; border-collapse: collapse; margin: 0 0 1.5em 0;
            width: 100%;">
            <tbody>
                <tr>
                    <td style="width: 35mm; height: 1px; line-height: 1px; font-size: 1px;">
                        &nbsp;
                    </td>
                    <td>
                    </td>
                    <td style="width: 30mm; height: 1px; line-height: 1px; font-size: 1px;">
                        &nbsp;
                    </td>
                    <td>
                    </td>
                </tr>
                <tr>
                    <td colspan="4" style="font-weight: bold;">
                        <span id="litPatchedToCC" style="text-align: right; font-weight: bold;"></span>
                    </td>
                </tr>
                <tr>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        By:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        ABC
                    </td>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        From:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        CC
                    </td>
                </tr>
                <tr>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Date:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        29/03/2011 13:35
                    </td>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        To:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        Member Practice
                    </td>
                </tr>
                <tr>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Folder:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        A15-123456
                    </td>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Individual:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        Miss A B Test
                    </td>
                </tr>
                <tr>
                    <td colspan="2">
                        <hr width="100%" />
                    </td>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Of:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        Lorem &amp; Ipsum
                    </td>
                </tr>
                <tr>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Species:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        Bovine
                    </td>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Position:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        Member
                    </td>
                </tr>
                <tr>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Item Type:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                    </td>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Tel:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                        0123 01234
                    </td>
                </tr>
                <tr>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                    </td>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Other Nos:
                    </th>
                    <td style="font-weight: bold; padding: 2px 5px;">
                    </td>
                </tr>
                <tr>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Reason For Call:
                    </th>
                    <td colspan="3" style="font-weight: bold; padding: 2px 5px;">
                        Some Reason
                    </td>
                </tr>
                <tr>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                        Subject:
                    </th>
                    <td colspan="3" style="font-weight: bold; padding: 2px 5px;">
                        Some problem.
                    </td>
                </tr>
                <tr>
                    <th scope="row" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                    </th>
                    <td>
                    </td>
                    <th scope="row" colspan="2" style="text-align: right; font-weight: normal; padding: 2px 5px;">
                    </th>
                    <td colspan="2">
                    </td>
                </tr>
                <tr>
                    <td style="font-size: 1.5em; font-weight: bold; text-align: center;" colspan="4">
                        Internal
                    </td>
                </tr>
                <tr>
                    <td colspan="4" style="text-align: center; padding: 2px 5px;">
                        <hr width="100%" />
                    </td>
                </tr>
            </tbody>
        </table>
        <div style="padding: 2px 5px;">
            <p>
                Here we start the discussion.</p>
            <br />
            <p>
                Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
            <br />
            <p>
                Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.</p>
        </div>
    </div>
</body>
</html>

Thanks for any help. hofnarwillie

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1 Reply

0 votes
by (71.8m points)

It looks like HTMLWorker is choking on the two <hr width="100%" />. Since you said you're ugrading to V5.XX, it might also be good to start using XMLWorker to start parsing your HTML - the development team is recommending it. (the latest HTMLWorker source code even has a small reference pointing this out)

Tested with your extended HTML, it works, and isn't too bad to implement :)

using (Document document = new Document()) {
  PdfWriter writer = PdfWriter.GetInstance(document, Response.OutputStream);
  document.Open();
  try {
    StringReader sr = new StringReader(htmlString);
    XMLWorkerHelper.GetInstance().ParseXHtml(
      writer, document, sr
    );          
  }
  catch (Exception e) {
    throw;
  }
}

Tested in a web environment, so replace Response.OutputStream with the Stream of your choice.


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