How can I change XML-element name for field inherited from base class while doing serialization?
For example I have next base class:
public class One
{
public int OneField;
}
Serialization code:
static void Main()
{
One test = new One { OneField = 1 };
var serializer = new XmlSerializer(typeof (One));
TextWriter writer = new StreamWriter("Output.xml");
serializer.Serialize(writer, test);
writer.Close();
}
I get what I need:
<?xml version="1.0" encoding="utf-8"?>
<One xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<OneField>1</OneField>
</One>
Now I have created new class inherited from A with additional field and custom XML element name for it:
public class Two : One
{
[XmlElement("SecondField")]
public int TwoField;
}
Serialization code:
static void Main()
{
Two test = new Two { OneField = 1, TwoField = 2 };
var serializer = new XmlSerializer(typeof (Two));
TextWriter writer = new StreamWriter("Output.xml");
serializer.Serialize(writer, test);
writer.Close();
}
As a result I get next output:
<?xml version="1.0" encoding="utf-8"?>
<Two xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<OneField>1</OneField>
<SecondField>2</SecondField>
</Two>
The problem is that I want to change OneField in this output to FirstField without touching base class code (because I will use it too and the names must be original). How can I accomplish this?
Thank you.
Try this:
public class Two : One
{
private static XmlAttributeOverrides xmlOverrides;
public static XmlAttributeOverrides XmlOverrides
{
get
{
if (xmlOverrides == null)
{
xmlOverrides = new XmlAttributeOverrides();
var attr = new XmlAttributes();
attr.XmlElements.Add(new XmlElementAttribute("FirstField"));
xmlOverrides.Add(typeof(One), "OneField", attr);
}
return xmlOverrides;
}
}
[XmlElement("SecondField")]
public string TwoField;
}
And your serializer init is a lot easier:
var xmls = new System.Xml.Serialization.XmlSerializer(typeof(Two), Two.XmlOverrides);
Here's a workaround: Override the fields in the subclass and mark the overriden field with whatever name you need. For example,
class One
{
public int OneField { get; set; }
}
class Two : One
{
[XmlElement("FirstField")]
public new int OneField
{
get { return base.OneField; }
set { base.OneField = value; }
}
}
Related
I have a class that could be serialized on its own, for example:
[XmlRoot("NameOfMyRoot", Namespace = "myNamespace")]
public class Inner
{
public Inner(){}
public string SomeString { get; set; }
}
Which is perfectly serializing into (I am using ns alias for myNamespace, see full demo)
<?xml version="1.0" encoding="utf-16"?>
<NameOfMyRoot xmlns:ns="myNamespace">
<ns:SomeString></ns:SomeString>
</NameOfMyRoot>
Now I want this object to be part of another one (the wrapper):
[XmlRoot("Root")]
public class Outer<T>
{
public T Property{ get; set; }
public Outer(){}
public Outer(T inner)
{
Property = inner;
}
}
Which gives me this:
<?xml version="1.0" encoding="utf-16"?>
<Root xmlns:ns="myNamespace">
<Property>
<ns:SomeString></ns:SomeString>
</Property>
</Root>
What I want is just embedding inner object as-is into its parent, like so:
<?xml version="1.0" encoding="utf-16"?>
<Root>
<NameOfMyRoot xmlns:ns="myNamespace">
<ns:SomeString></ns:SomeString>
</NameOfMyRoot>
</Root>
Notice that namespace should not move to root, and I can't specify element's name, since there will be many different types.
Fiddle with full example.
Of cource, I can just serialize them separately and combine through some nasty string manipulation, but I hope there is a neat way to achieve this somehow.
There's no easy way to do that. You can do it at runtime, though:
// perhaps discover these details at runtime
var attribs = new XmlAttributeOverrides();
attribs.Add(typeof(Outer<Inner>), "Property", new XmlAttributes
{
XmlElements = { new XmlElementAttribute {ElementName = "NameOfMyRoot" } }
});
attribs.Add(typeof(Inner), "SomeString", new XmlAttributes
{
XmlElements = { new XmlElementAttribute { Namespace = "myNamespace"} }
});
var ser = new XmlSerializer(typeof(Outer<Inner>), attribs);
var obj = new Outer<Inner> { Property = new Inner { SomeString = "abc" } };
ser.Serialize(Console.Out, obj);
Note that you must store and re-use such a serializer; for simple new XmlSerializer() examples, the serializer is cached internally and re-used; however, for non-trivial cases like this, a new dynamic type is emitted each time, so you will leak memory (it won't be unloaded).
That gives you:
<Root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<NameOfMyRoot>
<SomeString xmlns="myNamespace">abc</SomeString>
</NameOfMyRoot>
</Root>
If you don't want the two xmlns alias declaration, those can be removed separately, but they do not change the meaning, at least to a compliant reader. Likewise, the ns can be added as an alias:
var obj = new Outer<Inner> { Property = new Inner { SomeString = "abc" } };
var ns = new XmlSerializerNamespaces();
ns.Add("", "");
ns.Add("ns", "myNamespace");
ser.Serialize(Console.Out, obj, ns);
which gives:
<Root xmlns:ns="myNamespace">
<NameOfMyRoot>
<ns:SomeString>abc</ns:SomeString>
</NameOfMyRoot>
</Root>
As an alternative approach:
using System;
using System.Xml;
using System.Xml.Serialization;
[XmlRoot("NameOfMyRoot")]
public class Inner
{
public Inner() { }
[XmlElement(Namespace = "myNamespace")]
public string SomeString { get; set; }
}
static class Program
{
static void Main()
{
using (XmlWriter writer = XmlWriter.Create(Console.Out))
{
writer.WriteStartDocument(false);
writer.WriteStartElement("Root");
var ser = new XmlSerializer(typeof(Inner));
var obj = new Inner { SomeString = "abc" };
var ns = new XmlSerializerNamespaces();
ns.Add("", "");
ns.Add("ns", "myNamespace");
ser.Serialize(writer, obj, ns);
writer.WriteEndElement();
writer.WriteEndDocument();
}
}
}
What I've done here is to manually write the root node, and only get the XmlSerializer to write the inner content. Note that I had to change the attributes aroung SomeString to make it work in the way you expect (where it is the string that has the namespace, not the object).
I have a generic type Foo1 which is basically a container with some metadata and a generic list. When I serialize that type, it gets the name "Foo1Of" + TypeParameterName.
public class Foo1<T>
{
public string Name { get; set; } = string.Empty;
public List<T> List { get; set; } = new List<T>();
}
[TestMethod]
public void SerializeFoo1()
{
Foo1<string> foo = new Foo1<string>
{
Name = "Foo1",
List =
{
"Bar",
"Baz"
}
};
XmlSerializer s = new XmlSerializer(foo.GetType());
StringBuilder sb = new StringBuilder();
XmlWriter w = XmlWriter.Create(sb);
s.Serialize(w, foo);
Console.WriteLine(sb.ToString());
}
This is the old version and returns:
<?xml version="1.0" encoding="utf-16"?>
<Foo1OfString xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<Name>Foo1</Name>
<List><string>Bar</string><string>Baz</string></List>
</Foo1OfString>
To access the internal list more directly I implemented IEnumerable, IEnumerable and an Add(...) method.
public class Foo2<T> : IEnumerable<T>, IEnumerable
{
public string Name { get; set; } = string.Empty;
public List<T> List { get; set; } = new List<T>();
public void Add(T item)
{
List.Add(item);
}
public IEnumerator<T> GetEnumerator()
{
return List.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
return List.GetEnumerator();
}
}
[TestMethod]
public void SerializeFoo2()
{
Foo2<string> foo = new Foo2<string>
{
Name = "Foo2",
List =
{
"Bar",
"Baz"
}
};
XmlSerializer s = new XmlSerializer(foo.GetType());
StringBuilder sb = new StringBuilder();
XmlWriter w = XmlWriter.Create(sb);
s.Serialize(w, foo);
Console.WriteLine(sb.ToString());
}
After doing that, XML Serialization behaves very strange:
<?xml version="1.0" encoding="utf-16"?>
<ArrayOfString xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<string>Bar</string><string>Baz</string>
</ArrayOfString>
The name becomes "ArrayOf" + TypeParameterName and the property "Name" vanishes. The XmlSerializer seems to think, that my custom type is an array. Is there a way to change this behaviour which means to be able to implement the interfaces and Add(...) but get the old XML serialization?
This is default behavior of XmlSerializer as you are implementing IEnumerable<T> interface. Due to IEnumerable<string> type, XmlSerializer thinks it is a collection/array of string.
If you must implemented IEnumerable<T>, then one way to overcome this default behavior is to implement custom serialization. Implement IXmlSerializable for your Foo1<T>. You can then customize the Xml graph as you wish, and return your desired Name and List. XmlSerializer will then your custom implementation.
I have two classes. The base class has a public property with a DataMember. Now, I do not want this property to be serialized in the child class. I have no control over the parent class, and several other classes do inherit from it.
Is there a way to "hide" this attribute from the XmlSerializer that's used by WCF ? (the context here is a WCF RESTful web service).
Yes, it is possible using the XmlAttributeOverrides class, and the XmlIgnore property. Here is the example based on the one from MSDN:
public class GroupBase
{
public string GroupName;
public string Comment;
}
public class GroupDerived : GroupBase
{
}
public class Test
{
public static void Main()
{
Test t = new Test();
t.SerializeObject("IgnoreXml.xml");
}
public XmlSerializer CreateOverrider()
{
XmlAttributeOverrides xOver = new XmlAttributeOverrides();
XmlAttributes attrs = new XmlAttributes();
attrs.XmlIgnore = true; //Ignore the property on serialization
xOver.Add(typeof(GroupDerived), "Comment", attrs);
XmlSerializer xSer = new XmlSerializer(typeof(GroupDerived), xOver);
return xSer;
}
public void SerializeObject(string filename)
{
XmlSerializer xSer = CreateOverrider();
GroupDerived myGroup = new GroupDerived();
myGroup.GroupName = ".NET";
myGroup.Comment = "My Comment...";
TextWriter writer = new StreamWriter(filename);
xSer.Serialize(writer, myGroup);
writer.Close();
}
Result:
<?xml version="1.0" encoding="utf-8"?>
<GroupDerived xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<GroupName>.NET</GroupName>
</GroupDerived>
Result with XmlIgnore = false;:
<?xml version="1.0" encoding="utf-8"?>
<GroupDerived xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<GroupName>.NET</GroupName>
<Comment>My Comment...</Comment>
</GroupDerived>
I'm trying to use the XmlSerializer to persist a List(T) where T is an interface. The serializer does not like interfaces. I'm curious if there is a simple way to serialize a list of heterogeneous objects easily with XmlSerializer. Here's what I'm going for:
public interface IAnimal
{
int Age();
}
public class Dog : IAnimal
{
public int Age()
{
return 1;
}
}
public class Cat : IAnimal
{
public int Age()
{
return 1;
}
}
private void button1_Click(object sender, RoutedEventArgs e)
{
var animals = new List<IAnimal>
{
new Dog(),
new Cat()
};
var x = new XmlSerializer(animals.GetType());
var b = new StringBuilder();
var w = XmlTextWriter.Create(b, new XmlWriterSettings { NewLineChars = "\r\n", Indent = true });
//FAIL - cannot serialize interface. Does easy way to do this exist?
x.Serialize(w, animals);
var s = b.ToString();
}
You can use XmlSerializer as well, but you need to include all the possible types that can appear in the object graph you're serializing, which limits extensibility and lowers maintainability. You can do it by using an overload of the constructor of XmlSerializer:
var x = new XmlSerializer(animals.GetType(), new Type[] { typeof(Cat), typeof(Dog) });
Also, there are several issues of note when using XmlSerializer, all of the outlined here (MSDN) - for example look under the heading 'Dynamically generated assemblies'.
The XmlSerializer can't handle an interface because it doesn't know which types to create when deserialising. To get around this you need to handle that part of the serialization yourself by implementing the IXmlSerializable interface. This allows you to record the type so you can re-create (deserialise) it.
The ListOfIAnimal class below shows how I inherited and extended the generic list List<IAnimal> to implement the required interface. I squished up your old classes adding an extra non-interface field to each so I could see that the concrete classes were getting serialised and deserialised properly.
Compared to your code I'm just using the new type ListOfIAnimal in place of List<IAnimal>, the other changes are just a little refactoring.
Its complete code, just copy it into it's own .cs file, call the first function to step through it.
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Serialization;
namespace Serialiser
{
static class SerialiseInterface
{
public static void SerialiseAnimals()
{
String finalXml;
// Serialize
{
var animals = new ListOfIAnimal{
new Dog() { Age = 5, Teeth = 30 },
new Cat() { Age = 6, Paws = 4 }
};
var xmlSerializer = new XmlSerializer(animals.GetType());
var stringBuilder = new StringBuilder();
var xmlTextWriter = XmlTextWriter.Create(stringBuilder, new XmlWriterSettings { NewLineChars = "\r\n", Indent = true });
xmlSerializer.Serialize(xmlTextWriter, animals);
finalXml = stringBuilder.ToString();
}
// Deserialise
{
var xmlSerializer = new XmlSerializer(typeof(ListOfIAnimal));
var xmlReader = XmlReader.Create(new StringReader(finalXml));
ListOfIAnimal animals = (ListOfIAnimal)xmlSerializer.Deserialize(xmlReader);
}
}
}
public class ListOfIAnimal : List<IAnimal>, IXmlSerializable
{
public ListOfIAnimal() : base() { }
#region IXmlSerializable
public System.Xml.Schema.XmlSchema GetSchema() { return null; }
public void ReadXml(XmlReader reader)
{
reader.ReadStartElement("ListOfIAnimal");
while (reader.IsStartElement("IAnimal"))
{
Type type = Type.GetType(reader.GetAttribute("AssemblyQualifiedName"));
XmlSerializer serial = new XmlSerializer(type);
reader.ReadStartElement("IAnimal");
this.Add((IAnimal)serial.Deserialize(reader));
reader.ReadEndElement(); //IAnimal
}
reader.ReadEndElement(); //ListOfIAnimal
}
public void WriteXml(XmlWriter writer)
{
foreach (IAnimal animal in this)
{
writer.WriteStartElement("IAnimal");
writer.WriteAttributeString("AssemblyQualifiedName", animal.GetType().AssemblyQualifiedName);
XmlSerializer xmlSerializer = new XmlSerializer(animal.GetType());
xmlSerializer.Serialize(writer, animal);
writer.WriteEndElement();
}
}
#endregion
}
public interface IAnimal { int Age { get; set; } }
public class Dog : IAnimal { public int Age { get; set;} public int Teeth { get; set;} }
public class Cat : IAnimal { public int Age { get; set;} public int Paws { get; set;} }
}
I thought about leaving deserialize as an exercise for the reader, but the code would'n be very useful without it.
Do you have to use XmlSerializer? This is a known issue with XmlSerializer.
You can use BinaryFormatter to save to a stream:
BinaryFormatter bf = new BinaryFormatter();
MemoryStream ms = new MemoryStream();
bf.Serialize(ms, animals);
Other alternative is to use WCF's DataContractSerializer and provide types using KnownType attribute.
You can use ExtendedXmlSerializer.
var serializer = new ExtendedXmlSerializer();
var xml = serializer.Serialize(animals);
Your xml will look like:
<?xml version="1.0" encoding="utf-8"?>
<ArrayOfIAnimal>
<Dog type="Model.Dog" />
<Cat type="Model.Cat" />
</ArrayOfIAnimal>
The easy way is to add the [Serializable()] decoration to your classes
and change your IList to List and see if that works.
If you use interfaces then go see webturner's answer.
I am using VSTS2008 + C# + .Net 3.0. I am using below code to serialize XML, here is my current code and serialized XML file. My purpose is I want to make MyInnerObjectProperties belongs to a special XML namespace (http://foo/2009) and making this namespace as default namespace. Any ideas how to implement this?
Current output:
<?xml version="1.0"?>
<MyClass xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<MyObjectProperty>
<MyInnerObjectProperties>
<MyInnerObjectProperty>
<ObjectName>Foo Type</ObjectName>
</MyInnerObjectProperty>
<MyInnerObjectProperty>
<ObjectName>Goo Type</ObjectName>
</MyInnerObjectProperty>
</MyInnerObjectProperties>
</MyObjectProperty>
</MyClass>
Current code:
public class MyClass
{
private MyObject[] _myObjectProperty;
[XmlElement(IsNullable=false)]
public MyObject[] MyObjectProperty
{
get
{
return _myObjectProperty;
}
set
{
_myObjectProperty = value;
}
}
}
public class MyObject
{
private MyInnerObject[] _myInnerObjectProperty;
[XmlArrayItemAttribute("MyInnerObjectProperty", typeof(MyInnerObject), IsNullable=false)]
public MyInnerObject[] MyInnerObjectProperties
{
get
{
return _myInnerObjectProperty;
}
set
{
_myInnerObjectProperty = value;
}
}
}
public class MyInnerObject
{
public string ObjectName;
}
public class Program
{
static void Main(string[] args)
{
XmlSerializer s = new XmlSerializer(typeof(MyClass));
FileStream fs = new FileStream("foo.xml", FileMode.Create);
MyClass instance = new MyClass();
instance.MyObjectProperty = new MyObject[1];
instance.MyObjectProperty[0] = new MyObject();
instance.MyObjectProperty[0].MyInnerObjectProperties = new MyInnerObject[2];
instance.MyObjectProperty[0].MyInnerObjectProperties[0] = new MyInnerObject();
instance.MyObjectProperty[0].MyInnerObjectProperties[0].ObjectName = "Foo Type";
instance.MyObjectProperty[0].MyInnerObjectProperties[1] = new MyInnerObject();
instance.MyObjectProperty[0].MyInnerObjectProperties[1].ObjectName = "Goo Type";
s.Serialize(fs, instance);
return;
}
}
How about this:
[XmlArrayItemAttribute( Namespace = "http://foo.com/2009" /* other attr. params. */ )]
public MyInnerObject[] MyInnerObjectProperties
{
get { ... }
set { ... }
}
Try
public class MyObject
{
[XmlArrayItemAttribute("MyInnerObjectProperty", typeof (MyInnerObject),
IsNullable = false)]
[XmlArray(Namespace = "http://foo.com/2009")]
public MyInnerObject[] MyInnerObjectProperties { get; set; }
}
for me, this produces:
<?xml version="1.0" encoding="utf-8"?>
<MyClass xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<MyObjectProperty>
<MyInnerObjectProperties xmlns="http://foo.com/2009">
<MyInnerObjectProperty>
<ObjectName>Foo Type</ObjectName>
</MyInnerObjectProperty>
<MyInnerObjectProperty>
<ObjectName>Goo Type</ObjectName>
</MyInnerObjectProperty>
</MyInnerObjectProperties>
</MyObjectProperty>
</MyClass>
You need to create an XmlSerializerNamespaces object, and add your needed namespaces to it.
The XmlSerializerNamespaces object contains the XML namespaces and prefixes that the XmlSerializer uses to generate qualified names in an XML-document instance.
In your c# code:
XmlSerializerNamespaces myNameSpaces = new XmlSerializerNamespaces();
myNameSpaces.Add("MyInnerObject", "http://foo/2009");
Then, add an attribute to your class, like this:
public class MyInnerObject
{
[XmlElement(Namespace = "http://foo/2009")]
More info at:
http://msdn.microsoft.com/en-us/library/system.xml.serialization.xmlserializernamespaces.aspx