C# – How to Specify XML Encoding when Serializing an Object in C#

cencodingutf-8xml

I am serializing a C# object into an XML document and sending the XML document to a third party vendor. The vendor is telling me that the encoding specification in the document is UTF-16, but the XML document contains UTF-8 content and they can't use it. Here is the code I am using to create the XML file, which runs without error and creates an XML document.

// Instantiate xmlSerializer with my object type.
XmlSerializer xmlSerializer = new XmlSerializer(typeof(MyObject));

// Instantiate a new stream and pass file location and mode.
Stream stream = new FileStream(@"C:\doc.xml", FileMode.Create);

// Instantiate xmlWriter and pass stream and encoding.
XmlWriter xmlWriter = new XmlTextWriter(stream, Encoding.Unicode);

// Call serialize method and pass xmlWriter and my object.
xmlSerializer.Serialize(xmlWriter, myObject);

// Close writer and stream.
xmlWriter.Close();
stream.Close();

When I run this, the XML Doc shows this on the first line:

<?xml version="1.0" encoding="UTF-16"?>

I've tried changing the Encoding from Encoding.Unicode to Encoding.UTF8 in the XmlTextWriter, but that doesn't change the first line of the XML Doc and it still shows UTF-16.

I also tried using the Serialize method signature that takes 4 parameters (writer, object, namespaces, encoding) and specified UTF8 as the encoding and that didn't change the XML Doc specification either.

I believe all I need to do is change the encoding that shows in the XML Doc to UTF-8 and the third party vendor will be happy. I can't figure out what I am doing wrong.

Best Answer

If I change from Encoding.Unicode to Encoding.UTF8, the file is generated properly. Perhaps you're looking at an old version of your file?

In an unrelated bit, you should use using for deterministic disposal of objects which implement IDisposable:

XmlSerializer xmlSerializer = new XmlSerializer(typeof(MyObject));

using (Stream stream = new FileStream(@".\doc.xml", FileMode.Create))
using (XmlWriter xmlWriter = new XmlTextWriter(stream, Encoding.UTF8))
{
    xmlSerializer.Serialize(xmlWriter, myObject);
}

Related Solutions

C# – How to put an encoding attribute to xml other that utf-16 with XmlWriter

You need to use a StringWriter with the appropriate encoding. Unfortunately StringWriter doesn't let you specify the encoding directly, so you need a class like this:

public sealed class StringWriterWithEncoding : StringWriter
{
    private readonly Encoding encoding;

    public StringWriterWithEncoding (Encoding encoding)
    {
        this.encoding = encoding;
    }

    public override Encoding Encoding
    {
        get { return encoding; }
    }
}

(This question is similar but not quite a duplicate.)

EDIT: To answer the comment: pass the StringWriterWithEncoding to XmlWriter.Create instead of the StringBuilder, then call ToString() on it at the end.

C# – How to get a consistent byte representation of strings in C# without manually specifying an encoding

Contrary to the answers here, you DON'T need to worry about encoding if the bytes don't need to be interpreted!

Like you mentioned, your goal is, simply, to "get what bytes the string has been stored in".
(And, of course, to be able to re-construct the string from the bytes.)

For those goals, I honestly do not understand why people keep telling you that you need the encodings. You certainly do NOT need to worry about encodings for this.

Just do this instead:

static byte[] GetBytes(string str)
{
    byte[] bytes = new byte[str.Length * sizeof(char)];
    System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
    return bytes;
}

// Do NOT use on arbitrary bytes; only use on GetBytes's output on the SAME system
static string GetString(byte[] bytes)
{
    char[] chars = new char[bytes.Length / sizeof(char)];
    System.Buffer.BlockCopy(bytes, 0, chars, 0, bytes.Length);
    return new string(chars);
}

As long as your program (or other programs) don't try to interpret the bytes somehow, which you obviously didn't mention you intend to do, then there is nothing wrong with this approach! Worrying about encodings just makes your life more complicated for no real reason.

Additional benefit to this approach: It doesn't matter if the string contains invalid characters, because you can still get the data and reconstruct the original string anyway!

It will be encoded and decoded just the same, because you are just looking at the bytes.

If you used a specific encoding, though, it would've given you trouble with encoding/decoding invalid characters.

Best Answer

Related Solutions

C# – How to put an encoding attribute to xml other that utf-16 with XmlWriter

C# – How to get a consistent byte representation of strings in C# without manually specifying an encoding

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