Stack Empty exception on HTMLWorker in iTextSharp

Question

I am using this code to mail a datatable in the form of a pdf. But on converting the data using html parser, it is showing the exception as Stack Empty. However I have done this before and it worked, I just cant put my finger on what am I missing now. Please help!!!!!

using (StringWriter sw = new StringWriter())
    {
        using (HtmlTextWriter hw = new HtmlTextWriter(sw))
        {
            StringBuilder sb = new StringBuilder();
            //sb.Append("<table width='100%' cellspacing='0' cellpadding='2'>");


            foreach (DataColumn column in dt.Columns)
            {
                //sb.Append("<th style = 'background-color: #D20B0C;color:#ffffff'>");
                sb.Append(column.ColumnName);
                sb.Append("</th>");
            }
            sb.Append("</tr>");
            foreach (DataRow row in dt.Rows)
            {
                sb.Append("<tr>");
                foreach (DataColumn column in dt.Columns)
                {
                    sb.Append("<td>");
                    sb.Append(row[column]);
                    sb.Append("</td>");
                }
                sb.Append("</tr>");
            }
            sb.Append("</table>");


        using (MemoryStream memoryStream = new MemoryStream())
            {
                PdfWriter writer = PdfWriter.GetInstance(pdfDoc, memoryStream);
                pdfDoc.Open();                    
                htmlparser.Parse(sr);//here is the error
                pdfDoc.Close();
                byte[] bytes = memoryStream.ToArray();
                memoryStream.Close();

                MailMessage mm = new MailMessage(txtEmail.Text.Trim(), email.Trim());
                mm.Subject = txtSubject.Text.Trim();
                //mm.CC.Add = txtcc.Text.Trim();
                mm.Body = txtBody.Text.Trim();
                mm.Attachments.Add(new Attachment(new MemoryStream(bytes), "iTextSharpPDF.pdf"));
                mm.IsBodyHtml = true;
                SmtpClient smtp = new SmtpClient();
                smtp.Host = "smtp.gmail.com";
                smtp.EnableSsl = true;
                NetworkCredential NetworkCred = new NetworkCredential();
                NetworkCred.UserName = txtEmail.Text.Trim();
                NetworkCred.Password = txtPassword.Text.Trim();
                smtp.UseDefaultCredentials = true;
                smtp.Credentials = NetworkCred;
                smtp.Port = 587;
                smtp.Send(mm);
            }

} }

what is sr variable. If it is a HTML string then put a breakpoint on that line. And copy the HTML string and run some online html parser tool and check where is error. It looks like there is an issue in HTML string. — Deepak Kumar
– Deepak Kumar, Commented Aug 24, 2018 at 6:00
StringReader sr = new StringReader(sb.ToString()); Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f); HTMLWorker htmlparser = new HTMLWorker(pdfDoc); sr is the string reader and sb is the string builder — Tanvi Dutta
– Tanvi Dutta, Commented Aug 24, 2018 at 6:02
are you getting your html in string builder means sb.ToString() from html file or you build your html as hard coded in your program? — er-sho
– er-sho, Commented Aug 24, 2018 at 6:05

er-sho · Accepted Answer · 2018-08-24 07:26:27Z

2

1) Make you changes like below while building your html via StringBuilder like

StringBuilder sb = new StringBuilder();

//Open table
sb.Append("<table width='100%' cellspacing='0' cellpadding='2'>");

//Open first tr for all of th
sb.Append("<tr>");
foreach (DataColumn column in dt.Columns)
{
     sb.Append("<th style = 'background-color: #D20B0C;color:#ffffff'>");
     sb.Append(column.ColumnName);
     sb.Append("</th>");
}

//Close first tr for all of th
sb.Append("</tr>");


foreach (DataRow row in dt.Rows)
{   
    //Open tr for all of rows
    sb.Append("<tr>");
    foreach (DataColumn column in dt.Columns)
    {
        sb.Append("<td>");
        sb.Append(row[column]);
        sb.Append("</td>");
    }

    //Close tr for all of rows
    sb.Append("</tr>");
}


//Close table
sb.Append("</table>");

2) Use XMLWorkerHelper instead of HTMLWorker because now HTMLWorker is deprecated. and not more support by iTextSharp. like

PdfWriter writer = PdfWriter.GetInstance(pdfDoc, memoryStream);
pdfDoc.Open();
XMLWorkerHelper.GetInstance().ParseXHtml(writer, pdfDoc, sr);
pdfDoc.Close();
byte[] bytes = memoryStream.ToArray();
memoryStream.Close();

See this link

Try once may it help you.

edited Aug 24, 2018 at 7:26

answered Aug 24, 2018 at 7:19

er-sho

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2 Comments

er-sho Over a year ago

@Tanvi Dutta, view the answer might be it help you :)

er-sho Over a year ago

@Tanvi Dutta, if answer was helpful to you then accept it or let me know if you have any issue :)

Access Denied · Accepted Answer · 2018-08-24 07:19:46Z

You are missing openning tags, that's why component throws exception, since it reads closing tags which were not opened and stack is empty (probably it uses stack to track openning/closing tags):

using (StringWriter sw = new StringWriter())
    {
        using (HtmlTextWriter hw = new HtmlTextWriter(sw))
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("<table width='100%' cellspacing='0' cellpadding='2'>");
            sb.Append("<tr>");    

            foreach (DataColumn column in dt.Columns)
            {
                sb.Append("<th>");
                sb.Append(column.ColumnName);
                sb.Append("</th>");
            }
            sb.Append("</tr>");
            foreach (DataRow row in dt.Rows)
            {
                sb.Append("<tr>");
                foreach (DataColumn column in dt.Columns)
                {
                    sb.Append("<td>");
                    sb.Append(row[column]);
                    sb.Append("</td>");
                }
                sb.Append("</tr>");
            }
            sb.Append("</table>");

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