How do I add a custom XmlDeclaration with XmlDocument/XmlDeclaration?

Question

I would like to create a custom XmlDeclaration while using the XmlDocument/XmlDeclaration classes in c# .net 2 or 3.

This is my desired output (it is an expected output by a 3rd party app):

<?xml version="1.0" encoding="ISO-8859-1" ?>
<?MyCustomNameHere attribute1="val1" attribute2="val2" ?>
[ ...more xml... ]

Using the XmlDocument/XmlDeclaration classes, it appears I can only create a single XmlDeclaration with a defined set of parameters:

XmlDocument doc = new XmlDocument();
XmlDeclaration declaration = doc.CreateXmlDeclaration("1.0", "ISO-8859-1", null);
doc.AppendChild(declaration);

Is there a class other than the XmlDocument/XmlDeclaration I should be looking at to create the custom XmlDeclaration? Or is there a way with the XmlDocument/XmlDeclaration classes itself?

Answer 1

What you are wanting to create is not an XML declaration, but a "processing instruction". You should use the XmlProcessingInstruction class, not the XmlDeclaration class, e.g.:

XmlDocument doc = new XmlDocument();
XmlDeclaration declaration = doc.CreateXmlDeclaration("1.0", "ISO-8859-1", null);
doc.AppendChild(declaration);
XmlProcessingInstruction pi = doc.CreateProcessingInstruction("MyCustomNameHere", "attribute1=\"val1\" attribute2=\"val2\"");
doc.AppendChild(pi);

Answer 2

You would want to append a XmlProcessingInstruction created using the CreateProcessingInstruction method of the XmlDocument.

Example:

XmlDocument document        = new XmlDocument();
XmlDeclaration declaration  = document.CreateXmlDeclaration("1.0", "ISO-8859-1", "no");

string data = String.Format(null, "attribute1=\"{0}\" attribute2=\"{1}\"", "val1", "val2");
XmlProcessingInstruction pi = document.CreateProcessingInstruction("MyCustomNameHere", data);

document.AppendChild(declaration);
document.AppendChild(pi);