I'm working on some code to read an XML fragment which contains an XML declaration, e.g. <?xml version="1.0" encoding="utf-8"?>
and parse the encoding. From MSDN, I should be able to do it like this:
var nt = new NameTable();
var mgr = new XmlNamespaceManager(nt);
var context = new XmlParserContext(null, mgr, null, XmlSpace.None);
var reader = new System.Xml.XmlTextReader(@"<?xml version=""1.0"" encoding=""UTF-8""?>",
System.Xml.XmlNodeType.XmlDeclaration, context);
However, I'm getting a System.Xml.XmlException
on the call to the System.Xml.XmlTextReader
constructor with an error message:
XmlNodeType XmlDeclaration is not supported for partial content parsing.
I've googled this error in quotes -- exactly zero results found (edit: now there's one result: this post) -- and without quotes, which yields nothing useful. I've also looked at MSDN for the XmlNodeType, and it doesn't say anything about it not being supported.
What am I missing here? How can I get an XmlTextReader
instance from an XML declaration fragment?
Note, my goal here is just to determine the encoding of a partially-built XML document where I'm making the assumption that it at least contains a declaration node; thus, I'm trying to get reader.Encoding
. If there's another way to do that, I'm open to that.
At present, I'm parsing the declaration manually using regex, which is not the best approach.
Update: Getting the encoding from XML documentation or from XML fragment:
Here's a way to get the encoding without having to resort to fake root, using XmlReader.Create.
private static string GetXmlEncoding(string xmlString)
{
if (string.IsNullOrWhiteSpace(xmlString)) throw new ArgumentException("The provided string value is null or empty.");
using (var stringReader = new StringReader(xmlString))
{
var settings = new XmlReaderSettings { ConformanceLevel = ConformanceLevel.Fragment };
using (var xmlReader = XmlReader.Create(stringReader, settings))
{
if (!xmlReader.Read()) throw new ArgumentException(
"The provided XML string does not contain enough data to be valid XML (see https://msdn.microsoft.com/en-us/library/system.xml.xmlreader.read)");
var result = xmlReader.GetAttribute("encoding");
return result;
}
}
}
Here's the output, with a full and fragment XML:
If you want to have System.Text.Encoding, you can modify the code to look like this:
private static Encoding GetXmlEncoding(string xmlString)
{
using (StringReader stringReader = new StringReader(xmlString))
{
var settings = new XmlReaderSettings { ConformanceLevel = ConformanceLevel.Fragment };
var reader = XmlReader.Create(stringReader, settings);
reader.Read();
var encoding = reader.GetAttribute("encoding");
var result = Encoding.GetEncoding(encoding);
return result;
}
}
Old answer:
As you mentioned, XmlTextReader's Encoding-property contains the encoding.
Here's a full Console app's source code which hopefully is useful:
class Program
{
static void Main(string[] args)
{
var asciiXML = @"<?xml version=""1.0"" encoding=""ASCII""?><note><to>Tove</to><from>Jani</from><heading>Reminder</heading><body>Don't forget me this weekend!</body></note>";
var utf8XML = @"<?xml version=""1.0"" encoding=""UTF-8""?><note><to>Tove</to><from>Jani</from><heading>Reminder</heading><body>Don't forget me this weekend!</body></note>";
var asciiResult = GetXmlEncoding(asciiXML);
var utfResult = GetXmlEncoding(utf8XML);
Console.WriteLine(asciiResult);
Console.WriteLine(utfResult);
Console.ReadLine();
}
private static Encoding GetXmlEncoding(string s)
{
var stream = new MemoryStream(Encoding.UTF8.GetBytes(s));
using (var xmlreader = new XmlTextReader(stream))
{
xmlreader.MoveToContent();
var encoding = xmlreader.Encoding;
return encoding;
}
}
}
Here's the output from the program:
If you know that the XML only contains the declaration, maybe you can add an empty root? So for example:
var fragmentResult = GetXmlEncoding(xmlFragment + "<root/>");
Good evening, here's the solution with a System.Text.Encoding as output. I made it to be clear, and step by step.
class Program
{
static void Main(string[] args)
{
var line = File.ReadLines(YourFileName).First();
var correctXml = line + "<Root></Root>";
var xml = XDocument.Parse(correctXml);
var stringEncoding = xml.Declaration.Encoding;
var encoding = System.Text.Encoding.GetEncoding(stringEncoding);
}
}
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