Using CDATA with WCF REST starter kits

Question

Hey Everyone,

I have a service built using Preview 2 of the WCF REST starter kit, but I've run into an issue with passing around xml-styled data in the calls. Here's my request object:

[DataContract(Namespace = "")]
public class ServiceRequest
{
    [DataMember]
    public string ContentText { get; set; }
    [DataMember]
    public string ApiKey { get; set; }

}

Everything works fine until you throw '' in there. Is there a to encapsulate the ContentText property in a CDATA or something similar?

Thanks in advance!

Answer 1

Marc Gravell has a solution here for serializing CDATA sections.

I have copied the code here for posterity.

using System;
using System.IO;
using System.Runtime.Serialization;
using System.Xml;
using System.Xml.Serialization;
using System.ComponentModel;

public sealed class CDataWrapper : IXmlSerializable
{
// implicit to/from string
public static implicit operator string(CDataWrapper value)
{
return value == null ? null : value.Value;
}
public static implicit operator CDataWrapper(string value)
{
return value == null ? null : new CDataWrapper { Value =
value };
}
public System.Xml.Schema.XmlSchema GetSchema()
{
return null;
}
// "" => <Node/>
// "Foo" => <Node><![CDATA[Foo]]></Node>
public void WriteXml(XmlWriter writer)
{
if (!string.IsNullOrEmpty(Value))
{
writer.WriteCData(Value);
}
}
// <Node/> => ""
// <Node></Node> => ""
// <Node>Foo</Node> => "Foo"
// <Node><![CDATA[Foo]]></Node> => "Foo"
public void ReadXml(XmlReader reader)
{
if (reader.IsEmptyElement)
{
Value = "";
}
else
{
reader.Read();
switch (reader.NodeType)
{
case XmlNodeType.EndElement:
Value = ""; // empty after all...
break;
case XmlNodeType.Text:
case XmlNodeType.CDATA:
Value = reader.ReadContentAsString();
break;
default:
throw new InvalidOperationException("Expected text/
cdata");
}
}
}
// underlying value
public string Value { get; set; }
public override string ToString()
{
return Value;
}
}

// example usage
[DataContract(Namespace="http://myobjects/")]
public sealed class MyType
{
public string SomeValue { get; set; }
[DataMember(Name = "SomeValue", EmitDefaultValue = false)]
private CDataWrapper SomeValueCData
{
get { return SomeValue; }
set { SomeValue = value; }
}

public string EmptyTest { get; set; }
[DataMember(Name = "EmptyTest", EmitDefaultValue = false)]
private CDataWrapper EmptyTestCData
{
get { return EmptyTest; }
set { EmptyTest = value; }
}

public string NullTest { get; set; }
[DataMember(Name = "NullTest", EmitDefaultValue = false)]
private CDataWrapper NullTestCData
{
get { return NullTest ; }
set { NullTest = value; }
}
}

// test rig
static class Program
{
static void Main()
{

DataContractSerializer dcs =
new DataContractSerializer(typeof(MyType));

StringWriter writer = new StringWriter();
using (XmlWriter xw = XmlWriter.Create(writer))
{
MyType foo = new MyType
{
SomeValue = @"&<t\d",
NullTest = null,
EmptyTest = ""
};
ShowObject("Original", foo);

dcs.WriteObject(xw, foo);
xw.Close();
}
string xml = writer.ToString();
ShowObject("Xml", xml);

StringReader reader = new StringReader(xml);
using (XmlReader xr = XmlReader.Create(reader))
{
MyType bar = (MyType) dcs.ReadObject(xr);
ShowObject("Recreated", bar);
}
}
static void ShowObject(string caption, object obj)
{
Console.WriteLine();
Console.WriteLine("** {0} **", caption );
Console.WriteLine();
if (obj == null)
{
Console.WriteLine("(null)");
} else if (obj is string) {
Console.WriteLine((string)obj);
}
else
{
foreach (PropertyDescriptor prop in
TypeDescriptor.GetProperties(obj))
{
Console.WriteLine("{0}:\t{1}", prop.Name,
prop.GetValue(obj) ?? "(null)");
}
}
}
}