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Fast, dependency-free XML serializer for .NET written in F#
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README.markdown

SharpXml

SharpXml is an independent, dependency-free and fast .NET XML serialization library. It is written in F# and is built on .NET 4.0.

build status

The project is inspired by the great .NET JSON serializer ServiceStack.Text.

Get it

You can get SharpXml either by installing via nuget, by downloading the precompiled binaries or by cloning the git repository from github and compiling the library on your own.

NuGet

SharpXml can be found and installed via nuget:

PM> Install-Package SharpXml

Download binaries

You can also download the latest precompiled binaries using the downloads page on github:

Building from source

Alternatively you can clone the git repository and compile the project by yourself:

git clone git://github.com/kongo2002/SharpXml.git
cd SharpXml
msbuild

Linux

Using mono under linux you just have to replace msbuild with xbuild to build the project:

git clone git://github.com/kongo2002/SharpXml.git
cd SharpXml
xbuild

Release build

You may pass build configuration options to msbuild/xbuild in order to compile a release build:

xbuild /p:Configuration=Release;Optimize=true

Lean API

The API tries to appear small and descriptive at the same time:

// Serialization functions

string XmlSerializer.SerializeToString<T>(T element);
string XmlSerializer.SerializeToString(object element, Type targetType);

void XmlSerializer.SerializeToWriter<T>(TextWriter writer, T element);
void XmlSerializer.SerializeToWriter(TextWriter writer, object element, Type targetType);

// Deserialization functions

T XmlSerializer.DeserializeFromString<T>(string value);
object XmlSerializer.DeserializeFromString(string value, Type targetType);

T XmlSerializer.DeserializeFromReader<T>(TextReader reader);
object XmlSerializer.DeserializeFromReader(TextReader reader, Type targetType);

T XmlSerializer.DeserializeFromStream<T>(Stream stream);
object XmlSerializer.DeserializeFromStream(Stream stream, Type targetType);

Supported types

T can be any .NET POCO type. Apart from others SharpXml supports all basic collection types residing in System.Collections, System.Collections.Generic and System.Collections.Specialized:

  • List<T>
  • Dictionary<TKey, TValue>
  • ICollection<T>
  • IEnumerable<T>
  • IList
  • HashSet<T>
  • Nullable<T>
  • ReadOnlyCollection<T>
  • Queue<T>
  • Stack<T>
  • LinkedList<T>
  • SortedSet<T>
  • NameValueCollection
  • HashTable
  • ArrayList
  • CLR Arrays

Moreover SharpXml supports serialization and deserialization of the basic F# types being:

  • F# records
  • F# and CLR tuples
  • Immutable F# lists
  • Discriminated unions (since v1.5.0.0)

Configuration

SharpXml intends to work in a convention based manner meaning that there won't be too many configuration options to change its basic (de-)serialization behavior. A few options to modify SharpXml's output exist anyways:

  • XmlConfig.IncludeNullValues: Whether to include null values in the generated/serialized output (default: false)

  • XmlConfig.ExcludeTypeInfo: Whether to include additional type information for dynamic or anonymous types (default: false)

  • XmlConfig.EmitCamelCaseNames: Whether to convert property/type names into camel-case output, i.e. MyClass -> "myClass" (default: false)

  • XmlConfig.WriteXmlHeader: Whether to include a XML header sequence (<?xml ... ?>) in the serialized output (default: false)

  • XmlConfig.ThrowOnError: Whether to throw an exception on deserialization errors or silently ignore errors (default: false)

  • XmlConfig.UseAttributes: Activates deserialization and serialization support for XML attributes (see below for more information) (default: false)

Custom serialization

Although SharpXml comes with built-in support of all basic .NET types there are two ways to modify its de-/serialization behavior. You can either add custom serialization and/or deserialization logic by registering serialization delegates for a specified type on the static XmlConfig class or you can modify serialization of collections using the XmlElementAttribute in the SharpXml.Common namespace.

Moreover the serialization and deserialization of struct types may be customized by overriding the public ToString() method and/or providing a static ParseXml() function.

Registering delegates

/// Register a serializer delegate for the specified type
void RegisterSerializer<T>(SerializerFunc func);

/// Register a deserializer delegate for the specified type
void RegisterDeserializer<T>(DeserializerFunc func);

/// Unregister the serializer delegate for the specified type
void UnregisterSerializer<T>();

/// Unregister the deserializer delegate for the specified type
void UnregisterDeserializer<T>();

/// Clear all registered custom serializer delegates
void ClearSerializers();

/// Clear all registered custom deserializer delegates
void ClearDeserializers();

XmlElementAttribute

The XmlElementAttribute in SharpXml.Common allows you to modify the default serialization of .NET types using a few properties to choose from:

  • [XmlElement Name="..."]: Override the default name of the property/class

  • [XmlElement ItemName="..."]: Override the default name of collection's items (default: "item")

  • [XmlElement KeyName="..."]: Override the default name of keys in dictionary types (default: "key")

  • [XmlElement ValueName="..."]: Override the default name of values in dictionary types (default: "value")

  • [XmlElement Namespace="..."]: Defines a XML namespace attribute for the selected type or property (Note: this attribute is currently used for serialization of root types only)

    Deprecated: this property is deprecated as of version 1.4.0.0 of SharpXml. Please use the XmlNamespaceAttribute instead.

XML format

In the following section I want to give a short description of the format SharpXml generates and expects on deserialization.

The first thing to mention is that public properties are serialized and deserialized only. Fields whether public or not are not serialized at the moment and won't be in the future! Attributes placed inside the XML tags are not supported either and are simply ignored. Apart from that serialization is pretty straight-forward and your XML looks like you would probably expect it anyway -- at least from my point of view :-)

Basic serialization

public class MyClass
{
	public int Foo { get; set; }
	public string Bar { get; set; }
}

var test = new MyClass { Foo = 144, Bar = "I like SharpXml very much" };

An instance of the class above will be serialized like the following:

<MyClass>
	<Foo>144</Foo>
	<Bar>I like SharpXml very much</Bar>
</MyClass>

Using XmlConfig.EmitCamelCaseNames = true; the generated XML output would look like this instead:

<myClass>
	<foo>144</foo>
	<bar>I like SharpXml very much</bar>
</myClass>

Collections

public class ListClass
{
	public int Id { get; set; }
	public List<string> Items { get; set; }
}

var test = new ListClass
	{
		Id = 20,
		Items = new List<string> { "one", "two" }
	};

SharpXml will generate the following XML:

<ListClass>
	<Id>20</Id>
	<Items>
		<Item>one</Item>
		<Item>two</Item>
	</Items>
</ListClass>

Key-value collections (dictionaries)

public class DictClass
{
	public int Id { get; set; }
	public Dictionary<string, int> Values { get; set; }
}

var test = new DictClass
	{
		Id = 753,
		Values = new Dictionary<string, int>
			{
				{ "ten", 10 },
				{ "eight", 8 }
			}
	};

The serialized output by SharpXml looks like the following:

<DictClass>
	<Id>753</Id>
	<Values>
		<Item>
			<Key>ten</Key>
			<Value>10</Value>
		</Item>
		<Item>
			<Key>eight</Key>
			<Value>8</Value>
		</Item>
	</Values>
</DictClass>

Discriminated unions

Since SharpXml version 1.5.0.0 F# discriminated unions are supported for serialization and deserialization as well.

type UnionType =
	| First
	| Second of int
	| Third of string * int

let unions = [
	UnionType.First;
	UnionType.Second 20;
	UnionType.Third ("test", 30)
	]

The above list of F# discriminated unions will be serialized like this:

<List>
	<UnionType>
		<First></First>
	</UnionType>
	<UnionType>
		<Second>20</Second>
	</UnionType>
	<UnionType>
		<Third>
			<Item1>test</Item1>
			<Item2>30</Item2>
		</Third>
	</UnionType>
</List>

Note: In all XML examples above indentation is added for convenience only.

Using XmlElementAttribute

As mentioned before you can use the XmlElementAttribute to customize the generated XML output which is especially useful for collection and dictionary types.

[XmlElement("CustomClass")]
public class CustomDictClass
{
	public int Id { get; set; }

	[XmlElement(ItemName="Element", KeyName="String", ValueName="Int")]
	public Dictionary<string, int> Values { get; set; }
}

var test = new CustomDictClass
	{
		Id = 753,
		Values = new Dictionary<string, int>
			{
				{ "ten", 10 },
				{ "eight", 8 }
			}
	};

This example shows the effect of the four major options given by the XmlElementAttribute: Name, ItemName, KeyName and ValueName.

<CustomClass>
	<Id>753</Id>
	<Values>
		<Element>
			<String>ten</String>
			<Int>10</Int>
		</Element>
		<Element>
			<String>eight</String>
			<Int>8</Int>
		</Element>
	</Values>
</CustomClass>

Root type namespaces

Using the property Namespace of the XmlElementAttribute you can set an optional namespace string that will be used on serialization of the root element of the resulting XML document:

Deprecated: this property is deprecated as of version 1.4.0.0 of SharpXml. Please use the XmlNamespaceAttribute instead!

[XmlElement(Namespace = "Some.Namespace")]
public class NamespaceClass
{
	public int Id { get; set; }
	public string Name { get; set; }
}

var test = new NamespaceClass { Id = 201, Name = "foo" };

The class described above will be serialized like the following:

<NamespaceClass xmlns="Some.Namespace">
	<Id>201</Id>
	<Name>foo</Name>
</NamespaceClass>

Static attribute values

Like mentioned before instead of using the attribute XmlElementAttribute to set a namespace at the root level you can use XmlNamespaceAttribute instead. This attribute class is supported since SharpXml 1.4.0.0.

You can achieve the same result of above like this:

[XmlNamespace("xmlns=\"Some.Namespace\"")]
public class NamespaceClass
{
	public int Id { get; set; }
	public string Name { get; set; }
}

Like this you can set multiple static attributes as well:

[XmlNamespace("xmlns=\"Some.Namespace\"", "version=\"2.3.4.0\"")]
public class MultipleNamespaceClass
{
	public int Id { get; set; }
	public string Name { get; set; }
}

Note: These attribute values are static and are used for serialization only. There is no actual matching or any validation logic against XML namespaces during the deserialization process.

Struct types

Non-reference types like struct may provide custom implementation of the methods ToString() and/or ParseXml() in order to customize SharpXml's serialization behavior.

A typical example might look like this:

public struct MyStruct
{
	public int X { get; set; }
	public int Y { get; set; }

	/// <summary>
	/// Custom ToString() implementation - will be used by SharpXml
	/// </summary>
	public override string ToString()
	{
		return X + "x" + Y;
	}

	/// <summary>
	/// Custom deserialization function used by SharpXml
	/// </summary>
	public static MyStruct ParseXml(string input)
	{
		var parts = input.Split('x');

		return new MyStruct
			{
				X = int.Parse(parts[0]),
				Y = int.Parse(parts[1])
			};
	}
}

var test = new MyStruct { X = 200, Y = 50 };

Using the struct type described above results in the following output:

<MyStruct>200x50</MyStruct>

Without the custom implementations the struct would be serialized like this:

<MyStruct>
	<X>200</X>
	<Y>50</Y>
</MyStruct>

Custom serialization delegates

Moreover reference types can be customized by registering custom serialization delegates to the static XmlConfig class using the aforementioned RegisterSerializer and RegisterDeserializer functions.

public class SomeClass
{
	public double Width { get; set; }
	public double Height { get; set; }
}

// register custom serializer
XmlConfig.RegisterSerializer<SomeClass>(x => return x.Width + "x" + x.Height);

// register custom deserializer
XmlConfig.RegisterDeserializer<SomeClass>(v => {
		var parts = v.Split('x');
		return new SomeClass
			{
				Width = double.Parse(parts[0]),
				Height = double.Parse(parts[1])
			};
	});

The resulting XML will look pretty much the same as the struct example described earlier but you can imagine the possibilities given by this approach.

Deserialization

The deserialization logic of SharpXml can be described as very fault-tolerant meaning that usually bad formatted or even invalid XML may be deserialized without errors.

  • Tag name matching is case insensitive

  • Closing tags don't have to be the same as the opening tag. The nesting of tags is more important here.

  • The order of the tags is irrelevant

  • Tag attributes are ignored by default (since version 1.4.0.0. XML attribute support can be enabled using XmlConfig.UseAttributes)

  • XML namespaces are ignored as well

  • XML parsing is not completely XML 1.0/1.1 compliant. I.e. comment parsing is just rudimentary implemented.

In order to provide a better view on how fault-tolerant SharpXml works I will give an example of a very bad formatted XML input that will be deserialized without any errors:

<myclass>
	< foo >20</fo>
	<BAR attr="ignored anyway">ham eggs< /bar>
</MyClass>

This XML above will be successfully deserialized into an instance of MyClass.

Type resolving

In case you do not know at compile time what type you have to deserialize the XML data into you can use the specific overload of the DeserializeFromString, DeserializeFromReader or DeserializeFromStream method that takes a TypeResolver parameter. This way you can determine the type based on the tag information of the XML root node.

This method may be especially useful in a web service scenario where you can deserialize the incoming XML data into the appropriate type and route the DTO into the specific handler routine. You could use this method like that:

using System;
using System.Reflection;

using SharpXml;

public interface IHandlerProvider
{
	Type DetermineType(XmlInfo info);
}

public class XmlHandlerProvider : IHandlerProvider
{
	public Type DetermineType(XmlInfo info)
	{
		// this would be some custom built logic to determine
		// the specific data type based on the given XML root node
		// information

		// this is just some dummy logic!

		var assembly = Assembly.GetExecutingAssembly();
		var type = assembly.GetType(info.Name);

		if (type == null)
		{
			var namespace = info.HasAttributes
				? info.Attributes.Find(a => a.Key == "xmlns")
				: null;

			if (namespace != null)
				type = assembly.GetType(namespace.Value);
		}

		if (type == null)
		{
			throw new NotSupportedException(
				string.Format("There is no handler for type '{0}'", info.Name));
		}

		return type;
	}
}

public void Process(string xmlString)
{
	IHandlerProvider provider = new XmlHandlerProvider();

	var data = XmlSerializer.DeserializeFromString(xmlString, provider.DetermineType);
}

The example above is just a dummy to give you an idea how this functionality could be integrated. The XmlInfo class contains the root name and a list with all of its attribute values (if UseAttributes is enabled).

XML attributes

Since SharpXml version 1.4.0.0 XML attributes are supported as well although not enabled by default. In order to use attributes in serialization and deserialization you have to enable the setting XmlConfig.UseAttributes:

// activate XML attribute support
XmlConfig.Instance.UseAttributes = true;

It is important to initially set this property before you actually use the XmlSerializer. Since all deserialization and serialization functions and type information are cached at the first time for any type you have to make sure the setting is set early. In case you have to reset the serializer cache you can trigger a refresh manually:

// clear both serializers and deserializers
XmlSerializer.ClearCache();

// basically the same like this:
//XmlSerializer.ClearSerializers();
//XmlSerializer.ClearDeserializers();

XmlConfig.Instance.UseAttributes = true;

Moreover attributes have to be marked with the XmlAttribute attribute in the SharpXml.Common namespace:

XmlAttribute

Use the XmlAttribute attribute to mark a specific property to be serialized/deserialized as an attribute:

public class AttributeClass
{
	public string Value { get; set; }

	[XmlAttribute]
	public int Version { get; set; }

	[XmlAttribute("Key")]
	public string Name { get; set; }
}

var test = new AttributeClass
{
	Value = "Test",
	Version = 2,
	Name = "Attribute Test"
};

The above example would result in the following XML:

<AttributeClass Version="2" Key="Attribute Test">
	<Value>Test</Value>
</AttributeClass>

The ordering of the XML attributes on serialization can not be manipulated or defined by the user.

XmlAttribute on List<T> types

Additionally it is supported to override the List<T> class in order to specify attributes on a collection base. This may look like the following:

public class AttributeList<T> : List<T>
{
	[XmlAttribute]
	public int Version { get; set; }
}

public class AttributeTest
{
	[XmlAttribute("Attr")]
	public string Attribute { get; set; }

	public AttributeList<string> Values { get; set; }
}

var values = new AttributeList<string>
{
	"one",
	"two"
};

values.Version = 5;

var test = new AttributeTest
{
	Attribute = "value",
	Values = values
};

Here is the resulting XML output:

<AttributeTest Attr="value">
	<Values Version="5">
		<Item>one</Item>
		<Item>two</Item>
	</Values>
</AttributeTest>

Todo

Some random things I am planning to work on in the future:

  • Extend documentation/README
  • Make SharpXml.Common an optional dependency
  • Investigate into additional performance tweaks
  • Additional unit tests
  • Improve error messages/handling

Maintainer

SharpXml is written by Gregor Uhlenheuer. You can reach me at kongo2002@gmail.com

License

SharpXml is licensed under the Apache license, Version 2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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