I have to load and deserialize an Xml file into an object. I can read the xml, get to the point where the object is described and parse the xml only from that part which is great, but there is a namespace declared in the root of the xml.
I don't understand why but when reading the xml, even though I read it from a given node, the xmlns attribute gets added to it, resulting in my program not being able to deserialize that into an object, due to the unexpected member.
My code:
public static SomeClass GetObjectFromXml (string path)
{
XmlReader reader = XmlReader.Create(path);
string wantedNodeContents = string.Empty;
while (reader.Read())
{
if (reader.NodeType == XmlNodeType.Element && reader.Name == "IWantThis")
{
wantedNodeContents = reader.ReadOuterXml();
break;
}
}
XmlSerializer xmlSerializer = new XmlSerializer(typeof(SomeClass));
System.IO.StringReader stringReader = new System.IO.StringReader(wantedNodeContents);
SomeClass loadedSomeClassXml = xmlSerializer.Deserialize(stringReader) as SomeClass;
return loadedSomeClassXml;
}
How could I get rid of the xmlns and deserialize the xml into an object?
XDocument provides you a bit of more flexibility at time of deserialize any XML. I had a similiar problem and it was resolve using the next snippet code:
///Type T must have a default constructor
private T XMLToObject (string pathXML)
{
T myObjectParsedFromXML= default(T);
LoadOptions loadOpt = LoadOptions.SetLineInfo;
XDocument xmlDocument = XDocument.Load(pathXML , loadOpt);
string namespaceXML = xmlDocument.Root.Name.Namespace.NamespaceName;
XmlSerializer serializer = new XmlSerializer(typeof(T), defaultNamespace: namespaceXML);
XmlReader XMLreader = xmlDocument.CreateReader();
myObjectParsedFromXML= (T)serializer.Deserialize(XMLreader);
return myObjectParsedFromXML;
}
In addition, XmlSerializer provides you a set of events for register any issue or error during serialization process:
XmlSerializer serializer = new XmlSerializer(typeof(T), defaultNamespace: namespaceXML);
serializer.UnknownAttribute += new XmlAttributeEventHandler((sender, args) =>
{
//Your code for manage the errors during serialization
});
serializer.UnknownElement += new XmlElementEventHandler((sender, args) =>
{
//Your code for manage the errors during serialization
});
You have a few issues here:
The default namespace attribute is added to the string returned by ReadOuterXml()
because ReadOuterXml()
is designed not to change the semantics of the returned XML . Apparently in your XML there is a default namespace applied to some parent node of <IWantThis>
-- which, being a default namespace, recursively applies to <IWantThis>
itself. To retain this namespace membership, ReadOuterXml()
must emit a default namespace as it writes out the nested XML.
If you really want to completely ignore namespaces on XML, you need to create a custom XmlReader
, eg as shown in
You need to construct an XmlSerializer
for SomeClass
whose expected root node is <IWantThis>
. You can do this using the XmlSerializer(Type, XmlRootAttribute)
constructor, however, if you do, you must statically cache and reuse the serializer to avoid a severe memory leak , as explained in Memory Leak using StreamReader and XmlSerializer .
You are creating a local copy wantedNodeContents
of the element you want to deserialize, then re-parsing that local copy. There is no need to do this, you can use XmlReader.ReadSubtree()
to deserialize just a portion of the XML.
Putting all these issues together, your GetObjectFromXml()
could look like:
public static partial class XmlExtensions
{
public static T GetObjectFromXml<T>(string path, string localName, string namespaceURI, bool ignoreNamespaces = false)
{
using (var textReader = new StreamReader(path))
return GetObjectFromXml<T>(textReader, localName, namespaceURI);
}
public static T GetObjectFromXml<T>(TextReader textReader, string localName, string namespaceURI, bool ignoreNamespaces = false)
{
using (var xmlReader = ignoreNamespaces ? new NamespaceIgnorantXmlTextReader(textReader) : XmlReader.Create(textReader))
return GetObjectFromXml<T>(xmlReader, localName, namespaceURI);
}
public static T GetObjectFromXml<T>(XmlReader reader, string localName, string namespaceURI)
{
while (reader.Read())
{
if (reader.NodeType == XmlNodeType.Element && reader.LocalName == "IWantThis" && reader.NamespaceURI == namespaceURI)
{
var serializer = XmlSerializerFactory.Create(typeof(T), localName, namespaceURI);
using (var subReader = reader.ReadSubtree())
return (T)serializer.Deserialize(subReader);
}
}
// Or throw an exception?
return default(T);
}
}
// This class copied from this answer https://stackoverflow.com/a/873281/3744182
// To https://stackoverflow.com/questions/870293/can-i-make-xmlserializer-ignore-the-namespace-on-deserialization
// By https://stackoverflow.com/users/48082/cheeso
// helper class to ignore namespaces when de-serializing
public class NamespaceIgnorantXmlTextReader : XmlTextReader
{
public NamespaceIgnorantXmlTextReader(System.IO.TextReader reader): base(reader) { }
public override string NamespaceURI { get { return ""; } }
}
public static class XmlSerializerFactory
{
// To avoid a memory leak the serializer must be cached.
// https://stackoverflow.com/questions/23897145/memory-leak-using-streamreader-and-xmlserializer
// This factory taken from
// https://stackoverflow.com/questions/34128757/wrap-properties-with-cdata-section-xml-serialization-c-sharp/34138648#34138648
readonly static Dictionary<Tuple<Type, string, string>, XmlSerializer> cache;
readonly static object padlock;
static XmlSerializerFactory()
{
padlock = new object();
cache = new Dictionary<Tuple<Type, string, string>, XmlSerializer>();
}
public static XmlSerializer Create(Type serializedType, string rootName, string rootNamespace)
{
if (serializedType == null)
throw new ArgumentNullException();
if (rootName == null && rootNamespace == null)
return new XmlSerializer(serializedType);
lock (padlock)
{
XmlSerializer serializer;
var key = Tuple.Create(serializedType, rootName, rootNamespace);
if (!cache.TryGetValue(key, out serializer))
{
cache[key] = serializer = new XmlSerializer(serializedType, new XmlRootAttribute { ElementName = rootName, Namespace = rootNamespace });
}
return serializer;
}
}
}
Demo fiddle here .
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