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Xamarin.Forms itext7 - There is no associate PdfWriter for making indirects

I am using itext7 to get the Stream of the file and fill in the form fields.
Here is my code:
using (MemoryStream outFile = new MemoryStream())
{
var streamFile = await App.GraphClient.Me.Drive.Items[item.Id].Content.Request().GetAsync();
using (PdfDocument pdf = new PdfDocument(new PdfReader(streamFile)))
{
PdfAcroForm form = PdfAcroForm.GetAcroForm(pdf, true);
IDictionary<String, PdfFormField> fields = form.GetFormFields();
PdfFormField toSet;
fields.TryGetValue("Full_Names", out toSet);
toSet.SetValue(Customer_Name.Text);
form.FlattenFields();
pdf.Close();
}
}
But I get an error on this line: toSet.SetValue(Customer_Name.Text); when trying to set the value, the error is:
There is no associate PdfWriter for making indirects.
My question is what am I doing wrong and how do I fix this? I am getting the file from OneDrive using Microsoft Graph API. The IDictionary of fields is getting populated and the name of field I am trying to set the value for is accurate.

The problem with your code is that you have dedicated outFile stream for the output result (the document with flattened fields) but you are not telling iText anything about that desired output destination.
PdfDocument has several constructors and the one you are using is PdfDocument(PdfReader) and it is dedicated for reading the document, not changing it (and setting a value is considered changing the document of course). So you should use PdfDocument(PdfReader, PdfWriter) constructor to provide the source document and the target destination to iText.
You should create your PdfDocument as follows:
PdfDocument pdf = new PdfDocument(new PdfReader(streamFile), new PdfWriter(outFile))
At the end of the execution, your outFile stream will contain the bytes of the resultant document.

iText C#: Remove creation date

Is it possible to modify/remove the creation date in metadata? I'm looking to do something similar to this:
Overwrite creationDate in pdf using iText and pdf writer
EDIT:
I have tried the following methods:
writer.Info.Remove(PdfName.CREATIONDATE);
or
writer.Info.Put(PdfName.CREATIONDATE, new PdfDate(new DateTime(2017, 01, 01)));
where writer is a PdfWriter object.
However, that creates a copy of the object (a PdfDictionary) and doesn't modify the PDF I'm creating.
I also can't assign i.e. writer.Info = info
I tried following the advice given in the Java article.
I tried to do this:
var info = writer.Info;
stamper.MoreInfo = info
where stamper is a PdfStamper
But the types are incompatible and I don't think this would work. Does anyone know the actual methods to remove/modify the metadata?
EDIT 2:
Here is the code, I'm creating a new file from an existing PDF.
var filename = #"C:\Users\Someone\Documents\aPdf.pdf";
using( var output = new MemoryStream() )
{
Document document = new Document();
PdfCopy writer = new PdfCopy( document, output );
writer.CloseStream = false;
document.Open();
//read in PDF
PdfReader reader = new PdfReader(filename);
reader.ConsolidateNamedDestinations();
PdfImportedPage page = writer.GetImportedPage(reader, 1);
writer.AddPage(page);
reader.Close();
writer.Close();
document.Close();
return output.ToArray();
}
Now, when I open the file with a text editor this line is inserted (I need it constant/gone):
<</Producer(iTextSharp’ 5.5.12 ©2000-2017 iText Group NV \(AGPL-version\))/CreationDate(D:20180412155130+01'00')/ModDate(D:20180412155130+01'00')>>
The reason why we need to remove/set the date is that we're taking the MD5 hash of the file. Every time a new document is generated, that line changes leading to different MD5 hashes.

As I was trying to get a constant MD5 checksum for the generated file, I had to also set the ID constant, as mentioned by mkl.
My solution was to search byte array produced (i.e. the created PDF), and manually set the values to constants. The text is ASCII chars. I removed the /CreationDate and /ModifiedDated from the PDF entirely, and set the generated ID to a constant arbitrary value.

Export arabic data into pdf asp.net showing error

When I export ARABIC data into pdf.Microsoft adobereader showing error.Adobe reader could not open file because it is either not a supported file.My code is following asp.net c#.Guide me
protected void btnExport_Click(object sender, EventArgs e)
{
Response.ContentType = "application/pdf";
Response.AddHeader("content-disposition", "attachment;filename=TestPage.pdf");
Document doc = new Document(PageSize.LETTER);
doc.Open();
//Sample HTML
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.Append(#"<p>This is a test: <strong>مسندم</strong></p>");
//Path to our font
string arialuniTff = Server.MapPath("~/tradbdo.TTF");
//Register the font with iTextSharp
iTextSharp.text.FontFactory.Register(arialuniTff);
//Create a new stylesheet
iTextSharp.text.html.simpleparser.StyleSheet ST = new iTextSharp.text.html.simpleparser.StyleSheet();
//Set the default body font to our registered font's internal name
ST.LoadTagStyle(HtmlTags.BODY, HtmlTags.FACE, "Traditional Arabic Bold");
//Set the default encoding to support Unicode characters
ST.LoadTagStyle(HtmlTags.BODY, HtmlTags.ENCODING, BaseFont.IDENTITY_H);
//Parse our HTML using the stylesheet created above
List<IElement> list = HTMLWorker.ParseToList(new StringReader(stringBuilder.ToString()), ST);
//Loop through each element, don't bother wrapping in P tags
foreach (var element in list)
{
doc.Add(element);
}
doc.Close();
Response.Write(doc);
Response.End();
}

I found the following article which shows how to correctly export and display Arabic content via the iTextSharp library: http://geekswithblogs.net/JaydPage/archive/2011/11/02/using-itextsharp-to-correctly-display-hebrew--arabic-text-right.aspx.
Here is the code sample that you can try:
using iTextSharp.text;
using iTextSharp.text.pdf;
using System.Text.RegularExpressions;
using System.IO;
using System.Diagnostics;
public void WriteDocument()
{
//Declare a itextSharp document
Document document = new Document(PageSize.A4);
//Create our file stream and bind the writer to the document and the stream
PdfWriter writer = PdfWriter.GetInstance(document, new FileStream(#"C:\Test.Pdf", FileMode.Create));
//Open the document for writing
document.Open();
//Add a new page
document.NewPage();
//Reference a Unicode font to be sure that the symbols are present.
BaseFont bfArialUniCode = BaseFont.CreateFont(#"C:\ARIALUNI.TTF", BaseFont.IDENTITY_H, BaseFont.EMBEDDED);
//Create a font from the base font
Font font = new Font(bfArialUniCode, 12);
//Use a table so that we can set the text direction
PdfPTable table = new PdfPTable(1);
//Ensure that wrapping is on, otherwise Right to Left text will not display
table.DefaultCell.NoWrap = false;
//Create a regex expression to detect hebrew or arabic code points
const string regex_match_arabic_hebrew = #"[\u0600-\u06FF,\u0590-\u05FF]+";
if (Regex.IsMatch("مسندم", regex_match_arabic_hebrew, RegexOptions.IgnoreCase))
{
table.RunDirection = PdfWriter.RUN_DIRECTION_RTL;
}
//Create a cell and add text to it
PdfPCell text = new PdfPCell(new Phrase("مسندم", font));
//Ensure that wrapping is on, otherwise Right to Left text will not display
text.NoWrap = false;
//Add the cell to the table
table.AddCell(text);
//Add the table to the document
document.Add(table);
//Close the document
document.Close();
//Launch the document if you have a file association set for PDF's
Process AcrobatReader = new Process();
AcrobatReader.StartInfo.FileName = #"C:\Test.Pdf";
AcrobatReader.Start();
}

The iTextSharp.text.Document is a class used to help bridge human concepts like Paragraph and Margin into PDF concepts. The bridge part is important. It is not a PDF file in any way so it should never be treated as a PDF. Doing so would be like treating System.Drawing.Graphics as if it were an image. This leads to one of your problems on the second to last line of code that tries to treat the Document as if it were a PDF by sending it directly to the output stream:
//This won't work
Response.Write(doc);
You will find many, many tutorials out there that do this and they are all wrong. Fortunately (or unfortunately), PDF is forgiving and allows junk data at the end so only a handful of PDF fail and people assume there was some other problem.
Your other problem is that you are missing a PdfWriter. If Document is the bridge, PdfWriter is the actual construction worker that puts that PDF together. It, however, is also not a PDF. Instead, it needs to be bound to a stream like a file, in-memory or the HttpResponse.OutputStream.
Below is some code that shows this off. I very strongly recommend separating your PDF logic from your ASPX logic. Do all of you PDF stuff first and get an actual "something" that represents a PDF, then do something with it.
At the beginning we declare a byte array that we'll fill in later. Next we create a System.IO.MemoryStream that will be used to write the PDF to. After creating the Document we then create a PdfWriter that's bound to the Document and our stream. Your internal code is the same and although I didn't test it it appears correct. Right before we're done with our MemoryStream we grab the active bytes into our byte array. Lastly we use the BinaryWrite() method to send our raw binary PDF to the requesting client.
//At the end of this bytes will hold a byte array representing an actual PDF file
Byte[] bytes;
//Create a simple in-memory stream
using (var ms = new MemoryStream()){
using (var doc = new Document()) {
//Create a new PdfWriter bound to our document and the stream
using (var writer = PdfWriter.GetInstance(doc, ms)) {
doc.Open();
//This is unchanged from the OP's code
//Sample HTML
StringBuilder stringBuilder = new StringBuilder();
stringBuilder.Append(#"<p>This is a test: <strong>مسندم</strong></p>");
//Path to our font
string arialuniTff = Server.MapPath("~/tradbdo.TTF");
//Register the font with iTextSharp
iTextSharp.text.FontFactory.Register(arialuniTff);
//Create a new stylesheet
iTextSharp.text.html.simpleparser.StyleSheet ST = new iTextSharp.text.html.simpleparser.StyleSheet();
//Set the default body font to our registered font's internal name
ST.LoadTagStyle(HtmlTags.BODY, HtmlTags.FACE, "Traditional Arabic Bold");
//Set the default encoding to support Unicode characters
ST.LoadTagStyle(HtmlTags.BODY, HtmlTags.ENCODING, BaseFont.IDENTITY_H);
//Parse our HTML using the stylesheet created above
List<IElement> list = HTMLWorker.ParseToList(new StringReader(stringBuilder.ToString()), ST);
//Loop through each element, don't bother wrapping in P tags
foreach (var element in list) {
doc.Add(element);
}
doc.Close();
}
}
//Right before closing the MemoryStream grab all of the active bytes
bytes = ms.ToArray();
}
//We now have a valid PDF and can do whatever we want with it
//In this case, use BinaryWrite to send it directly to the requesting client
Response.ContentType = "application/pdf";
Response.AddHeader("content-disposition", "attachment;filename=TestPage.pdf");
Response.BinaryWrite(bytes);
Response.End();

How to add new page in pdf for multiple record iTextsharp

I have an xml and mapping to pdf form field using iTextsharp. It works well for single record. But when multiple records are there, it does not add 2nd record in the output pdf. Here is a code
public static void GeneratePdf(string sin, List<XElement> elements)
{
var pdfTemplate = HttpContext.Current.Server.MapPath("~/input.pdf");
var newFile = HttpContext.Current.Server.MapPath("~/output.pdf");
var pdfReader = new PdfReader(pdfTemplate);
var pdfStamper = new PdfStamper(pdfReader, new FileStream(
newFile, FileMode.Create));
foreach (var element in elements)
{
foreach (var elem in elements.Elements())
{
pdfStamper.AcroFields.SetField(elem.Name.ToString(), (string)elem);
}
}
pdfStamper.FormFlattening = false;
pdfStamper.Close();
}

Your question is unclear because you're telling us nothing about the nature of your form.
IF YOU'RE FORM IS BASED ON ACROFORM TECHNOLOGY
Please take a look at this video tutorial: http://itextpdf.com/codenvy_webapp
You can find the examples used in this tutorial here: https://github.com/blowagie/itextsamples
You can also find the standalone examples here: http://itextpdf.com/sandbox/acroforms/reporting
Note that there's an example "HOW NOT TO DO IT". Make sure you use the correct example: FillFlattenMerge2
Document document = new Document();
PdfCopy copy = new PdfSmartCopy(document, new FileOutputStream(dest));
document.open();
ByteArrayOutputStream baos;
PdfReader reader;
PdfStamper stamper;
AcroFields fields;
while (myApp.hasMoreRecords()) {
baos = new ByteArrayOutputStream();
reader = new PdfReader(SRC);
stamper = new PdfStamper(reader, baos);
fields = stamper.getAcroFields();
myApp.processNextRecord(fields);
stamper.setFormFlattening(true);
stamper.close();
reader.close();
// add the PDF to PdfCopy
reader = new PdfReader(baos.toByteArray());
copy.addDocument(reader);
reader.close();
}
document.close();
Note that myApp is an instance of a custom class you could write to loop over a record set. You'd implement a method hasMoreRecords() and processNextRecord() to loop over the records and process them one by one.
IF YOUR FORM IS BASED ON THE XML FORMS ARCHITECTURE
In this case, you're using the wrong methods. You can't fill out a dynamic form using the setField() method. The fact that it works for one record is a sign that your form is either an AcroForm or a hybrid XFA form. In both cases you can NOT achieve what you want without changing your form into a pure, dynamic XFA form.
As soon as you have a pure, dynamic XFA form, you need to use this code:
PdfReader reader = new PdfReader(src);
PdfStamper stamper = new PdfStamper(reader,
new FileOutputStream(dest));
AcroFields form = stamper.getAcroFields();
XfaForm xfa = form.getXfa();
xfa.fillXfaForm(new FileInputStream(xml));
stamper.close();
reader.close();
I repeat: this code snippet will only work if you have a correct form. Elements in your question indicate that this is not the case. If your form isn't a dynamic XFA form, you won't find any software that can achieve what you want!!!
Watch these movies for more info: http://itextpdf.com/product/xfa_worker

Altering PDF through iTextSharp to Replace some existing text with a new text

Please tell me if is there any function in iTextSharp that dose replace(”xx”,”yy”) function in the pdf file without altering remaining parts of the file.

Short answer: NO you cannot do that with iText.
Longer Answer: PDF is a display format, so when the PDF is rendered many decisions are made about page and character layout and positioning. Chapter 6 of iText in Action has a great description in the introduction of why it is not a trivial task. You can read Chapter 6 for free from the publisher's website.

I found a way to do this through PDF form Fields.
String formFile = Server.MapPath("~/") + "source.pdf";
String newFile = Server.MapPath("~/") + "sink.pdf";
PdfReader reader = new PdfReader(formFile);
PdfStamper stamper = new PdfStamper(reader, new FileStream(newFile, FileMode.Create));
AcroFields fields = stamper.AcroFields;
// set form fields
fields.SetField("{TO}", "John Doe");
fields.SetField("{FROM}", "2 Milky Way, London");
stamper.FormFlattening = true;
stamper.Close();