C# XmlSerializer - вывод нескольких фрагментов XML, управляющих новыми строками ⇐ C#

[Anonymous]

I want to be able to write fragments of indented XML with no namespaces, no XML preambles, and \n for line endings, using XmlSerializer for each fragment and using a single XmlWriter instance for all the fragments. How can I do that?

XmlSerializer.Serialize() produces indented output when serializing to a generic output Stream, but it uses "\n\r" for line endings and I can't find how to configure that.

I can serialize to an XmlWriter, which can be configured in detail, but the config only seems to work when you output complete a single document rather than multiple document fragments because XmlSerializer will throw an exception with ConformanceLevel.Fragment:

WriteStartDocument cannot be called on writers created with ConformanceLevel.Fragment

And, if as a workaround I call XmlWriter.WriteWhitespace("");, indentation gets disabled. Specifically, If I create an XmlWriter like this:

XmlWriter xw = XmlWriter.Create(System.Console.Out, new XmlWriterSettings() { ConformanceLevel = ConformanceLevel.Fragment, NamespaceHandling = NamespaceHandling.Default, NewLineChars = "\n", Encoding = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false), // supress BOM Indent = true, NewLineHandling = NewLineHandling.Replace, OmitXmlDeclaration = true, WriteEndDocumentOnClose = false, CloseOutput = false, CheckCharacters = false, NewLineOnAttributes = false, }); MVE https://dotnetfiddle.net/qGLIlL It does allow me to serialize multiple objects without creating a new XmlWriter for each one. But there's no indentation.

public class Program { public static void Main() { XmlWriter xw = XmlWriter.Create(System.Console.Out, new XmlWriterSettings() { ConformanceLevel = ConformanceLevel.Fragment, NamespaceHandling = NamespaceHandling.Default, NewLineChars = "\n", Encoding = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false), // supress BOM Indent = true, NewLineHandling = NewLineHandling.Replace, OmitXmlDeclaration = true, WriteEndDocumentOnClose = false, CloseOutput = false, CheckCharacters = false, NewLineOnAttributes = false, }); var noNamespace = new XmlSerializerNamespaces(new[] { XmlQualifiedName.Empty }); // without this line I get an error: // "WriteStartDocument cannot be called on writers created with ConformanceLevel.Fragment." xw.WriteWhitespace(""); FlyingMonkey monkey = FlyingMonkey.Create(); XmlSerializer ser = new XmlSerializer(typeof(FlyingMonkey), defaultNamespace: null); ser.Serialize(xw, monkey, noNamespace); xw.WriteWhitespace("\n\n"); monkey.name = "New Name"; ser.Serialize(xw, monkey, noNamespace); } } [System.Xml.Serialization.XmlTypeAttribute(TypeName = "flyingMonkey", Namespace=null)] public class FlyingMonkey { [System.Xml.Serialization.XmlAttributeAttribute()] public string name; public Limb[] limbs; public static FlyingMonkey Create() => new FlyingMonkey() { name = "Koko", limbs = new Limb[] { new Limb() { name = "leg" }, new Limb() { name = "arm" }, new Limb() { name = "tail" }, new Limb() { name = "wing" }, } }; } [System.Xml.Serialization.XmlTypeAttribute(TypeName = "limb", Namespace=null)] public class Limb { [System.Xml.Serialization.XmlAttributeAttribute()] public string name; } What kinda works: XmlWriter xw = XmlWriter.Create(System.Console.Out, new XmlWriterSettings() { ConformanceLevel = ConformanceLevel.Auto, NamespaceHandling = NamespaceHandling.Default, NewLineChars = "\n", Encoding = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false), // supress BOM Indent = true, NewLineHandling = NewLineHandling.Replace, OmitXmlDeclaration = true, WriteEndDocumentOnClose = false, CloseOutput = false, CheckCharacters = false, NewLineOnAttributes = false, }); var noNamespace = new XmlSerializerNamespaces(new[] { XmlQualifiedName.Empty }); // This is not needed anymore. If I invoke that, it will kill indentation for some reason. // xw.WriteWhitespace(""); FlyingMonkey monkey = FlyingMonkey.Create(); XmlSerializer ser = new XmlSerializer(typeof(FlyingMonkey), defaultNamespace: null); ser.Serialize(xw, monkey, noNamespace); // xw.WriteWhitespace("\n\n"); // monkey.name = "New Name"; // ser.Serialize(xw, monkey, noNamespace); // this second serialization throws InvalidOperationException It does print with right line endings, but won't let you write another object to the same XmlWriter instance.

I want to reuse my single instance of XmlWriter because I need to be writing up to 100k elements, and creating an XmlWriter for each one adds a lot of overhead


Источник: https://stackoverflow.com/questions/780 ... -new-lines