Say we have a class like:
using System;
using System.Xml.Serialization;
namespace XmlEntities {
[XmlRoot("Agent")]
public class RootClass {
private string element_description;
[XmlElement("Name")]
public string Name{ get; set; }
}
[XmlElement("Surname")]
public string Surname{ get; set; }
}
}
And we want to serialize into xml only Name XmlElement. How to limit that at serialization?
Have you encountered the [XmlIgnore] attribute? Adding it to members of your class will exclude them from serialization.
So, for example, you can replace [XmlElement("Surname")] with [XmlIgnore], and then your serialized agent will look like this:
<Agent>
<Name>John Doe</Name>
</Agent>
Alternately, if all you really want is just <Name>John Doe</Name>, you could write a wrapper class:
[XmlRoot("Name")]
public class NameElement
{
[XmlText]
public string Name { get; set; }
}
* EDIT *
While it's possible to generate such wrappers at runtime, it's difficult, inefficient, and not very practical.
To do so, I guess you could reflectively examine your object and find the properties you want (root.GetType().GetProperties().Where(p => /* your logic here */)), and use System.Reflection.Emit to generate the appropriate class. While possible, it's not reasonable - it'd be a huge amount of code relative to your actual logic, and you could easily destabilize the runtime and/or leak memory.
A better way to achieve the dynamicism you want is to forego System.Xml.Serialization and use System.Xml.Linq. This would require you to write code that built up the xml yourself, but it's super easy:
public XElement ConvertToXml(RootClass root)
{
return new XElement("Name", root.Name);
}
You can write an XElement to any stream using the element.Save(Stream) instance method on XElement.
Read more about Linq to XML at MSDN
If you want to ignore the element at runtime, at serialization, you can use XmlAttributeOverrides:
XmlAttributeOverrides overrides = new XmlAttributeOverrides();
XmlAttributes attribs = new XmlAttributes();
attribs.XmlIgnore = true;
attribs.XmlElements.Add(new XmlElementAttribute("Surname"));
overrides.Add(typeof(RootClass), "Surname", attribs);
XmlSerializer ser = new XmlSerializer(typeof(RootClass), overrides);
RootClass agent = new RootClass();
agent.Name = "Marc";
agent.Surname = "Jobs";
ser.Serialize(Console.Out, agent);
Related
I am successfully using XML serializer to serialize a Microsoft.VisualStudio.Services.Common.SerializableDictionary<T1, T2>.
Now I want to add a guid string to SerializableDictionary and serialize it as well. I therefore created the following class:
public class SerializableDictWithGuid<T1, T2> : SerializableDictionary<T1, T2>, IMyInterface
{
[XmlElement(ElementName = idXml001)]
public string Guid { get; set; } = string.Empty;
}
When serializing SerializableDictWithGuid with the below code, the guid string is missing in the XML output.
public class XmlSerializeHelper<T> where T : class
{
public static string Serialize(T obj)
{
try
{
System.Xml.Serialization.XmlSerializer xsSubmit = new System.Xml.Serialization.XmlSerializer(typeof(T));
using (var sww = new StringWriter())
{
using (XmlTextWriter writer = new XmlTextWriter(sww) { Formatting = Formatting.Indented })
{
xsSubmit.Serialize(writer, obj);
}
return sww.ToString();
}
}
catch (Exception ex)
{
logger.log(ex);
}
return string.Empty;
}
}
Minimal reproducible example
SerializableDictWithGuid <string, string> test = new SerializableDictWithGuid <string, string>() { Guid = "123" };
XmlSerializeHelper<SerializableDictWithGuid <string, string>>.Serialize(test);
Question: how can I add properties to SerializableDictionary and include them in XML serialization?
XmlSerializer does not support dictionaries, so SerializableDictionary<T1, T2> works by implementing IXmlSerializable. I.e., it serializes itself manually using handcrafted code. As such, that code knows nothing about the properties of subclasses, and doesn't have any code to discover and serialize them automatically.
Luckily it appears that IXmlSerializable.ReadXml() and IXmlSerializable.WriteXml() were not implemented explicitly, so it should be possible to re-implement them via interface re-implementation and still call the base class methods. And, while in general it's tricky to implement IXmlSerializable, if you make your Guid be an XML attribute rather than an element, implementation becomes simple because, while the design of IXmlSerializable doesn't allow for derived classes to inject child elements, it does allow for derived classes to inject custom attributes:
public class SerializableDictWithGuid<T1, T2> : SerializableDictionary<T1, T2>, IMyInterface, IXmlSerializable // Re-implement IXmlSerializable
{
const string idXml001 = "idXml001";
public string Guid { get; set; } = string.Empty;
public new void ReadXml(XmlReader reader)
{
reader.MoveToContent();
// At this point the reader is positioned on the beginning of the container element for the dictionary, so we can get any custom attributes we wrote.
Guid = reader.GetAttribute(idXml001);
base.ReadXml(reader);
}
public new void WriteXml(XmlWriter writer)
{
// At this point the container element has been written but nothing else, so it's still possible to add some attributes.
if (Guid != null)
writer.WriteAttributeString(idXml001, Guid);
base.WriteXml(writer);
}
}
This results in XML that looks like:
<SerializableDictWithGuidOfStringString idXml001="123">
<item>
<key>
<string>hello</string>
</key>
<value>
<string>there</string>
</value>
</item>
</SerializableDictWithGuidOfStringString>
The XML Standard states that
Attributes are used to associate name-value pairs with elements.
In general attributes are appropriate for fixed sets of simple, primitive values such as names and IDs. Complex values with multiple internal properties, or values that repeat (i.e. collections) should be child elements, not attributes. Since an identifying Guid is a primitive value, using an attribute is appropriate. See:
XML attribute vs XML element
Should I use Elements or Attributes in XML?
Demo fiddle here.
I would like to XML serialize an object that has (among other) a property of type IModelObject (which is an interface).
public class Example
{
public IModelObject Model { get; set; }
}
When I try to serialize an object of this class, I receive the following error:
"Cannot serialize member Example.Model of type Example because it is an interface."
I understand that the problem is that an interface cannot be serialized. However, the concrete Model object type is unknown until runtime.
Replacing the IModelObject interface with an abstract or concrete type and use inheritance with XMLInclude is possible, but seems like an ugly workaround.
Any suggestions?
This is simply an inherent limitation of declarative serialization where type information is not embedded within the output.
On trying to convert <Flibble Foo="10" /> back into
public class Flibble { public object Foo { get; set; } }
How does the serializer know whether it should be an int, a string, a double (or something else)...
To make this work you have several options but if you truly don't know till runtime the easiest way to do this is likely to be using the XmlAttributeOverrides.
Sadly this will only work with base classes, not interfaces. The best you can do there is to ignore the property which isn't sufficient for your needs.
If you really must stay with interfaces you have three real options:
Hide it and deal with it in another property
Ugly, unpleasant boiler plate and much repetition but most consumers of the class will not have to deal with the problem:
[XmlIgnore()]
public object Foo { get; set; }
[XmlElement("Foo")]
[EditorVisibile(EditorVisibility.Advanced)]
public string FooSerialized
{
get { /* code here to convert any type in Foo to string */ }
set { /* code to parse out serialized value and make Foo an instance of the proper type*/ }
}
This is likely to become a maintenance nightmare...
Implement IXmlSerializable
Similar to the first option in that you take full control of things but
Pros
You don't have nasty 'fake' properties hanging around.
you can interact directly with the xml structure adding flexibility/versioning
Cons
you may end up having to re-implement the wheel for all the other properties on the class
Issues of duplication of effort are similar to the first.
Modify your property to use a wrapping type
public sealed class XmlAnything<T> : IXmlSerializable
{
public XmlAnything() {}
public XmlAnything(T t) { this.Value = t;}
public T Value {get; set;}
public void WriteXml (XmlWriter writer)
{
if (Value == null)
{
writer.WriteAttributeString("type", "null");
return;
}
Type type = this.Value.GetType();
XmlSerializer serializer = new XmlSerializer(type);
writer.WriteAttributeString("type", type.AssemblyQualifiedName);
serializer.Serialize(writer, this.Value);
}
public void ReadXml(XmlReader reader)
{
if(!reader.HasAttributes)
throw new FormatException("expected a type attribute!");
string type = reader.GetAttribute("type");
reader.Read(); // consume the value
if (type == "null")
return;// leave T at default value
XmlSerializer serializer = new XmlSerializer(Type.GetType(type));
this.Value = (T)serializer.Deserialize(reader);
reader.ReadEndElement();
}
public XmlSchema GetSchema() { return(null); }
}
Using this would involve something like (in project P):
public namespace P
{
public interface IFoo {}
public class RealFoo : IFoo { public int X; }
public class OtherFoo : IFoo { public double X; }
public class Flibble
{
public XmlAnything<IFoo> Foo;
}
public static void Main(string[] args)
{
var x = new Flibble();
x.Foo = new XmlAnything<IFoo>(new RealFoo());
var s = new XmlSerializer(typeof(Flibble));
var sw = new StringWriter();
s.Serialize(sw, x);
Console.WriteLine(sw);
}
}
which gives you:
<?xml version="1.0" encoding="utf-16"?>
<MainClass
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<Foo type="P.RealFoo, P, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null">
<RealFoo>
<X>0</X>
</RealFoo>
</Foo>
</MainClass>
This is obviously more cumbersome for users of the class though avoids much boiler plate.
A happy medium may be merging the XmlAnything idea into the 'backing' property of the first technique. In this way most of the grunt work is done for you but consumers of the class suffer no impact beyond confusion with introspection.
The solution to this is using reflection with the DataContractSerializer. You don't even have to mark your class with [DataContract] or [DataMember]. It will serialize any object, regardless of whether it has interface type properties (including dictionaries) into xml. Here is a simple extension method that will serialize any object into XML even if it has interfaces (note you could tweak this to run recursively as well).
public static XElement ToXML(this object o)
{
Type t = o.GetType();
Type[] extraTypes = t.GetProperties()
.Where(p => p.PropertyType.IsInterface)
.Select(p => p.GetValue(o, null).GetType())
.ToArray();
DataContractSerializer serializer = new DataContractSerializer(t, extraTypes);
StringWriter sw = new StringWriter();
XmlTextWriter xw = new XmlTextWriter(sw);
serializer.WriteObject(xw, o);
return XElement.Parse(sw.ToString());
}
what the LINQ expression does is it enumerates each property,
returns each property that is an interface,
gets the value of that property (the underlying object),
gets the type of that concrete object
puts it into an array, and adds that to the serializer's list of known types.
Now the serializer knows how about the types it is serializing so it can do its job.
If you know your interface implementors up-front there's a fairly simple hack you can use to get your interface type to serialize without writing any parsing code:
public interface IInterface {}
public class KnownImplementor01 : IInterface {}
public class KnownImplementor02 : IInterface {}
public class KnownImplementor03 : IInterface {}
public class ToSerialize {
[XmlIgnore]
public IInterface InterfaceProperty { get; set; }
[XmlArray("interface")]
[XmlArrayItem("ofTypeKnownImplementor01", typeof(KnownImplementor01))]
[XmlArrayItem("ofTypeKnownImplementor02", typeof(KnownImplementor02))]
[XmlArrayItem("ofTypeKnownImplementor03", typeof(KnownImplementor03))]
public object[] InterfacePropertySerialization {
get { return new[] { InterfaceProperty }; ; }
set { InterfaceProperty = (IInterface)value.Single(); }
}
}
The resulting xml should look something along the lines of
<interface><ofTypeKnownImplementor01><!-- etc... -->
You can use ExtendedXmlSerializer. This serializer support serialization of interface property without any tricks.
var serializer = new ConfigurationContainer().UseOptimizedNamespaces().Create();
var obj = new Example
{
Model = new Model { Name = "name" }
};
var xml = serializer.Serialize(obj);
Your xml will look like:
<?xml version="1.0" encoding="utf-8"?>
<Example xmlns:exs="https://extendedxmlserializer.github.io/v2" xmlns="clr-namespace:ExtendedXmlSerializer.Samples.Simple;assembly=ExtendedXmlSerializer.Samples">
<Model exs:type="Model">
<Name>name</Name>
</Model>
</Example>
ExtendedXmlSerializer support .net 4.5 and .net Core.
Replacing the IModelObject interface with an abstract or concrete type and use inheritance with XMLInclude is possible, but seems like an ugly workaround.
If it is possible to use an abstract base I would recommend that route. It will still be cleaner than using hand-rolled serialization. The only trouble I see with the abstract base is that your still going to need the concrete type? At least that is how I've used it in the past, something like:
public abstract class IHaveSomething
{
public abstract string Something { get; set; }
}
public class MySomething : IHaveSomething
{
string _sometext;
public override string Something
{ get { return _sometext; } set { _sometext = value; } }
}
[XmlRoot("abc")]
public class seriaized
{
[XmlElement("item", typeof(MySomething))]
public IHaveSomething data;
}
Unfortunately there's no simple answer, as the serializer doesn't know what to serialize for an interface. I found a more complete explaination on how to workaround this on MSDN
Unfortuantely for me, I had a case where the class to be serialized had properties that had interfaces as properties as well, so I needed to recursively process each property. Also, some of the interface properties were marked as [XmlIgnore], so I wanted to skip over those. I took ideas that I found on this thread and added some things to it to make it recursive. Only the deserialization code is shown here:
void main()
{
var serializer = GetDataContractSerializer<MyObjectWithCascadingInterfaces>();
using (FileStream stream = new FileStream(xmlPath, FileMode.Open))
{
XmlDictionaryReader reader = XmlDictionaryReader.CreateTextReader(stream, new XmlDictionaryReaderQuotas());
var obj = (MyObjectWithCascadingInterfaces)serializer.ReadObject(reader);
// your code here
}
}
DataContractSerializer GetDataContractSerializer<T>() where T : new()
{
Type[] types = GetTypesForInterfaces<T>();
// Filter out duplicates
Type[] result = types.ToList().Distinct().ToList().ToArray();
var obj = new T();
return new DataContractSerializer(obj.GetType(), types);
}
Type[] GetTypesForInterfaces<T>() where T : new()
{
return GetTypesForInterfaces(typeof(T));
}
Type[] GetTypesForInterfaces(Type T)
{
Type[] result = new Type[0];
var obj = Activator.CreateInstance(T);
// get the type for all interface properties that are not marked as "XmlIgnore"
Type[] types = T.GetProperties()
.Where(p => p.PropertyType.IsInterface &&
!p.GetCustomAttributes(typeof(System.Xml.Serialization.XmlIgnoreAttribute), false).Any())
.Select(p => p.GetValue(obj, null).GetType())
.ToArray();
result = result.ToList().Concat(types.ToList()).ToArray();
// do the same for each of the types identified
foreach (Type t in types)
{
Type[] embeddedTypes = GetTypesForInterfaces(t);
result = result.ToList().Concat(embeddedTypes.ToList()).ToArray();
}
return result;
}
I have found a simpler solution (you don't need the DataContractSerializer), thanks to this blog here:
XML serializing derived types when base type is in another namespace or DLL
But 2 problems can rise in this implementation:
(1) What if DerivedBase is not in the namespace of class Base, or even worse in a project that depends on Base namespace, so Base cannot XMLInclude DerivedBase
(2) What if we only have class Base as a dll ,so again Base cannot XMLInclude DerivedBase
Till now, ...
So the solution to the 2 problems is by using XmlSerializer Constructor (Type, array[]) :
XmlSerializer ser = new XmlSerializer(typeof(A), new Type[]{ typeof(DerivedBase)});
A detailed example is provided here on MSDN:
XmlSerializer Constructor (Type, extraTypesArray[])
It seems to me that for DataContracts or Soap XMLs, you need to check the XmlRoot as mentioned here in this SO question.
A similar answer is here on SO but it isn't marked as one, as it not the OP seems to have considered it already.
in my project, I have a
List<IFormatStyle> FormatStyleTemplates;
containing different Types.
I then use the solution 'XmlAnything' from above, to serialize this list of different types.
The generated xml is beautiful.
[Browsable(false)]
[EditorBrowsable(EditorBrowsableState.Never)]
[XmlArray("FormatStyleTemplates")]
[XmlArrayItem("FormatStyle")]
public XmlAnything<IFormatStyle>[] FormatStyleTemplatesXML
{
get
{
return FormatStyleTemplates.Select(t => new XmlAnything<IFormatStyle>(t)).ToArray();
}
set
{
// read the values back into some new object or whatever
m_FormatStyleTemplates = new FormatStyleProvider(null, true);
value.ForEach(t => m_FormatStyleTemplates.Add(t.Value));
}
}
I would like to manage multiple customer standards efficiently.
If I open (deserialize) an XML, I want to determine which classes are used during deserialisation. Choosing another class basically means looking at the XML from an other perspective (view).
What I have right now:
I have a class Project which has some properties and methods.
I am able to serialize instances of motor to XML, this works fine.
Also deserialization works fine.
Now I create a new class ProjectCustomerA, which is derived from the base class Project. I overwrite some of the methods on ProjectCustomerA and might add some in the future.
Both class Project and ProjectCustomerA share the same XmlType ([Serializable, XmlType("Project")]).
Now when I deserialize an XML I get an error that both classes use the same XmlType and that this is not possible.
Below is the message I get (it was originally in Dutch and I translated):
System.InvalidOperationException HResult=0x80131509 ... Inner
Exception 1: InvalidOperationException: The types C4M_Data.C4M_Project
and C4M_Data_customer.C4M_Project_Customer both use the XML-typename,
Project, from namespace . Use XML-attributes to define a unique
XML-name and/or -namespace for the type.
My question is how to read (deserialize) the same XML and let me control what classes are instantiated in my application during this process?
My current idea is that different types (all the same baseclass if needed) should result in an XML with the same root element and namespace. The XML should always look the same. Then I need to control / force the XmlSerializer to deserialize to the type I want, regardless of the root element name and namespace. Is this possible?
You cannot have multiple types in the type hierarchy have identical [XmlType] attributes. If you do, the XmlSerializer constructor will throw the exception you have seen, stating:
Use XML-attributes to define a unique XML-name and/or -namespace for the type.
The reason XmlSerializer requires unique element names and/or namespaces for all types in the hierarchy is that it is designed to be able to successfully serialize type information via the xsi:type mechanism - which becomes impossible if the XML names & namespaces are identical. You wish to make all the types in your root data model hierarchy be indistinguishable when serialized to XML which conflicts with this design intent of XmlSerializer.
Instead, when serializing, you can construct your XmlSerializer with the XmlSerializer(Type, XmlRootAttribute) constructor to specify a shared root element name and namespace to be used for all objects in your root model hierarchy. Then when deserializing you can construct an XmlSerializer using the root element name and namespace actually encountered in the file. The following extension methods do the job:
public static partial class XmlSerializationHelper
{
public static T LoadFromXmlAsType<T>(this string xmlString)
{
return new StringReader(xmlString).LoadFromXmlAsType<T>();
}
public static T LoadFromXmlAsType<T>(this TextReader textReader)
{
using (var xmlReader = XmlReader.Create(textReader, new XmlReaderSettings { CloseInput = false }))
return xmlReader.LoadFromXmlAsType<T>();
}
public static T LoadFromXmlAsType<T>(this XmlReader xmlReader)
{
while (xmlReader.NodeType != XmlNodeType.Element)
if (!xmlReader.Read())
throw new XmlException("No root element");
var serializer = XmlSerializerFactory.Create(typeof(T), xmlReader.LocalName, xmlReader.NamespaceURI);
return (T)serializer.Deserialize(xmlReader);
}
public static string SaveToXmlAsType<T>(this T obj, string localName, string namespaceURI)
{
var sb = new StringBuilder();
using (var writer = new StringWriter(sb))
obj.SaveToXmlAsType(writer, localName, namespaceURI);
return sb.ToString();
}
public static void SaveToXmlAsType<T>(this T obj, TextWriter textWriter, string localName, string namespaceURI)
{
using (var xmlWriter = XmlWriter.Create(textWriter, new XmlWriterSettings { CloseOutput = false, Indent = true }))
obj.SaveToXmlAsType(xmlWriter, localName, namespaceURI);
}
public static void SaveToXmlAsType<T>(this T obj, XmlWriter xmlWriter, string localName, string namespaceURI)
{
var serializer = XmlSerializerFactory.Create(obj.GetType(), localName, namespaceURI);
serializer.Serialize(xmlWriter, obj);
}
}
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;
}
}
}
Then, if your type hierarchy looks something like this:
public class Project
{
// Name for your root element. Replace as desired.
public const string RootElementName = "Project";
// Namespace for your project. Replace as required.
public const string RootElementNamespaceURI = "https://stackoverflow.com/questions/49977144";
public string BaseProperty { get; set; }
}
public class ProjectCustomerA : Project
{
public string CustomerProperty { get; set; }
public string ProjectCustomerAProperty { get; set; }
}
public class ProjectCustomerB : Project
{
public string CustomerProperty { get; set; }
public string ProjectCustomerBProperty { get; set; }
}
You can serialize an instance of ProjectCustomerA and deserialize it as an instance of ProjectCustomerB as follows:
var roota = new ProjectCustomerA
{
BaseProperty = "base property value",
CustomerProperty = "shared property value",
ProjectCustomerAProperty = "project A value",
};
var xmla = roota.SaveToXmlAsType(Project.RootElementName, Project.RootElementNamespaceURI);
var rootb = xmla.LoadFromXmlAsType<ProjectCustomerB>();
var xmlb = rootb.SaveToXmlAsType(Project.RootElementName, Project.RootElementNamespaceURI);
// Assert that the shared BaseProperty was deserialized successfully.
Assert.IsTrue(roota.BaseProperty == rootb.BaseProperty);
// Assert that the same-named CustomerProperty was ported over properly.
Assert.IsTrue(roota.CustomerProperty == rootb.CustomerProperty);
Notes:
I chose to put the shared XML element name and namespace as constants in the base type Project.
When constructing an XmlSerializer with an override root element name or namespace, it must be cached to avoid a memory leak.
All this being said, making it be impossible to determine whether a given XML file contains an object of type ProjectCustomerA or ProjectCustomerB seems like a dangerously inflexible design going forward. I'd encourage you to rethink whether this design is appropriate. For instance, you could instead serialize them with their default, unique element names and namespaces, and still deserialize to any desired type using the methods LoadFromXmlAsType<T>() above, which generate an XmlSerializer using the actual name and namespace found in the file.
The methods LoadFromXmlAsType<T>() may not work if there is an xsi:type attribute on the root element. If you want to ignore (or process) the xsi:type attribute then further work may be required.
Sample working .Net fiddle.
In my application I use the following code to serialze objects:
private static string Serialize(Type type, object objectToSerialize)
{
StringBuilder builder = new StringBuilder();
using (TextWriter writer = new StringWriter(builder))
{
XmlSerializer serializer = new XmlSerializer(type);
serializer.Serialize(writer, objectToSerialize);
}
return builder.ToString();
}
This code just worked fine until now.
We've introduced a new class which looks like:
[Serializable]
public class Restriction
{
public string Id { get; set; }
public ResticType Type { get; set; }
public Restriction Parent { get; set; }
public List<Restriction> Children { get; set; }
}
If I try to serialize it I get the following exception:
A circular reference was detected while serializing an object of type Restriction
I already found out, that this occures because of the Parent and the Children which are also of type Restriction
I've already tried to set the Parent-Property to NonSerialized but this doesn't work.
Unfortunately I can not change the code for serialization...
What can I do to serialize this class?
Actual my only idea is to implement IXmlSerializable in my Restriction-class and do the reading and writing of the xml by my own. I hope there is another way...
I've already tried to set the Parent-Property to NonSerialized but this doesn't work.
NonSerialized is for binary serialization. Use XmlIgnore instead.
Note that you'll have to manually restore the Parent property after deserialization:
void RestoreParentRelationship(Restriction restriction)
{
foreach (var child in restriction.Children)
child.Parent = restriction;
}
I'm trying to serialize the Outer class shown below, and create an XElement from the serialized XML. It has a property which is of type Inner. I'd like to change the name of both Inner (to Inner_X) and Outer (to Outer_X).
class Program
{
static void Main(string[] args)
{
using (MemoryStream memoryStream = new MemoryStream())
{
using (TextWriter streamWriter = new StreamWriter(memoryStream))
{
var xmlSerializer = new XmlSerializer(typeof(Outer));
xmlSerializer.Serialize(streamWriter, new Outer());
XElement result = XElement.Parse(Encoding.ASCII.GetString(memoryStream.ToArray()));
}
}
}
}
[XmlType("Outer_X")]
public class Outer
{
public Outer()
{
this.InnerItem = new Inner();
}
public Inner InnerItem { get; set; }
}
[XmlType("Inner_X")]
public class Inner
{
}
This creates an XElement which looks like this:
<Outer_X xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<InnerItem />
</Outer_X>
What I would like is:
<Outer_X xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<Inner_X />
</Outer_X>
I want to keep the information about how a class should be renamed with that class. I thought I could do this with the XmlType attribute. However, this is ignored and the property name is used instead.
I've looked here and here, amongst other places, and feel like this should work. What am I missing?
Clarification
By "keep(ing) the information about how a class should be renamed with that class", what I mean is that the term Inner_X should only appear in the Inner class. It should not appear at all in the Outer class.
When XmlSerializer serializes a type, the type itself controls the names of the elements created for its properties. I.e. the property name becomes the element name, unless overridden statically by XmlElementAttribute.ElementName. XmlTypeAttribute.TypeName generally only controls the element name when an instance of the type to which it is applied is not being serialized as the property of some containing type -- for instance, when it is the root element, or when it is contained in a collection that is being serialized with an outer container element. This design avoids name collisions in cases where there are multiple properties of the same type within a given type.
However, there is an exception in the case of polymorphic property types. For these, XmlSerializer has an option to use the XML type name of each of the possible polymorphic types as the element name, thereby identifying the actual c# type from which the element was created. To enable this functionality, one must add multiple [XmlElement(typeof(TDerived))] attributes to the property, one for each possible type TDerived.
You can use this capability to generate the XML you require by introducing a psuedo-polymorphic proxy property:
[XmlType("Outer_X")]
public class Outer
{
public Outer()
{
this.InnerItem = new Inner();
}
[XmlIgnore]
public Inner InnerItem { get; set; }
[XmlElement(typeof(Inner))]
[XmlElement(typeof(object))]
[Browsable(false), EditorBrowsable(EditorBrowsableState.Never), DebuggerBrowsable(DebuggerBrowsableState.Never)]
public object InnerItemXmlProxy
{
get
{
return InnerItem;
}
set
{
InnerItem = (Inner)value;
}
}
}
Then the output is as you require:
<Outer_X xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<Inner_X />
</Outer_X>
Prototype fiddle.
However, as #evk commented, if your Outer class contains multiple properties of the same type, this cannot be done.
One other option to think about: if you simply don't want to manually duplicate the "Inner_X" type name strings in multiple locations (i.e. in both the [XmlType(string name)] and [XmlElement(string name)] attributes) you could centralize the type names by making them be public const:
[XmlType(Outer.XmlTypeName)]
public class Outer
{
public const string XmlTypeName = "Outer_X";
public Outer()
{
this.InnerItem = new Inner();
}
[XmlElement(Inner.XmlTypeName)]
public Inner InnerItem { get; set; }
}
[XmlType(Inner.XmlTypeName)]
public class Inner
{
public const string XmlTypeName = "Inner_X";
}
Update
I just noticed your comment I intend Inner to be an abstract base class, each subclass of which will serialize to different element names. If this is the case, then XmlSerializer can indeed be made to use the XML type name as the element name -- but only when it can determine statically that the property type is actually polymorphic due to the presence of multiple [XmlElement(typeof(TDerived))] attributes. Thus the following classes will generate the XML you require:
[XmlType("Outer_X")]
public class Outer
{
public Outer()
{
this.InnerItem = new InnerX();
}
[XmlElement(typeof(InnerX))]
[XmlElement(typeof(Inner))] // Necessary to inform the serializer of polymorphism even though Inner is abstract.
public Inner InnerItem { get; set; }
}
public abstract class Inner
{
}
[XmlType("Inner_X")]
public class InnerX : Inner
{
}
You need to set the element name of the property, not the xml type of the inner class.
Try this:
[XmlType("Outer_X")]
public class Outer
{
public Outer()
{
this.InnerItem = new Inner();
}
[XmlElement("Inner_X")]
public Inner InnerItem { get; set; }
}
public class Inner
{
}
This is extremely simple to achieve. You need to use the XmlRootAttribute for the class and the XmlElementAttribute for the members as explained here on MSDN.
[XmlRoot(ElementName = "Outer_X")]
public class Outer
{
[XmlElement(ElementName = "Inner_X")]
public Inner InnerItem { get; set; } = new Inner();
}
public class Inner { }
I have created a working .NET Fiddle to exemplify this. This SO Q & A seemed to address this similar concern. Finally, when decoding the XML to a string you should probably use a different encoding, no? According to this, strings are UTF-16 encoded -- not a big deal, but figured I'd call attention to it.
The fiddle I shared results in the following XML:
<Outer_X xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<Inner_X />
</Outer_X>
Update
After you updated your question with the clarification, I now understand what you'd asking. Unfortunately, (to my knowledge) this cannot be controlled as you desire via attributes. You'd have to either create your own XML serializer / deserializer or accept the fact that there are limitations with the attribute support.