C#: Modifying the header of an XML file

Question

Hi, I am creating an XML file in C# using a XSD Schema of an InfoPath form.

When I save the IP form without using the code, I get an XML file with the following header:

<?xml version="1.0" encoding="UTF-8"?>
<?mso-infoPathSolution solutionVersion="1.0.0.113" productVersion="14.0.0" PIVersion="1.0.0.0" href="file:///\\Hmfp\mcs-shared\PMU\PMU-shared\Tests\QF%207.5%20PMU%20Project%20Outline%20Form%20F1.0.xsn" name="urn:schemas-microsoft-com:office:infopath:QF-7-5-PMU-Project-Outline-Form-F1-0:-myXSD-2010-07-22T07-48-32" ?>
<?mso-application progid="InfoPath.Document"?>
<my:myFields...

And this file is recognized by InfoPath and uses the correct XSD, thus displaying the XML data in the correct form.

But when I use the code, I get this:

<?xml version="1.0"?>
<myFields...

And this is not recognized nor opened directly by InfoPath; so I would like to insert the two tags in order to keep that functionality, so that the users do not see the difference.

My line of thought is to modify the XML file after it has already been created, saved and closed.

It would be very nice if you could help :D. Thanks in advance..

EDIT: I've finally been able to achieve what I wanted. I made use of both MainMa's and dahlbyk's answers and came up with something that works:

• I let the file get saved like before
• I created an XmlReader object from the file
• I loaded the XmlReader into an XmlDocument object
• I created an XmlProcessingInstruction object using XmlDocument.CreateProcessingInstruction
• I inserted that PI in the XmlDoc using xmlDoc.InsertAfter(thePI, XmlDoc.FirstChild)
• I then created a second PI object
• Which I inserted using xmlDoc.InsertAfter(thePI, XmlDoc.FirstChild.NextSibling)
• Then I saved the XmlDoc in the file, overwriting it

Anyway, your answers helped me understand many things, which made me find the answer, so thank you very much!!

Answer 1

The first three lines of your first code sample are called XML processing instructions (PI). So if you are creating your output XML with XmlDocument, you can use XmlDocument.CreateProcessingInstruction method to add the required PI.

If you are serializing into XML, you can also use XmlTextWriter.WriteProcessingInstruction just before serializing the object.

If for some reasons, you cannot do that, you can also save the file, open it and insert two PI after the first line break, but I highly discourage you to do that, since it will make your code difficult to maintain in future, and slow things down.

Answer 2

I would try making an XmlWriter for your FileStream, use WriteProcessingInstruction() to add your headers, then pass the writer into the appropriate overload of Serialize() to capture the rest of the output.