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KnownTypeAttribute Constructor (String)

Initializes a new instance of the KnownTypeAttribute class with the name of a method that returns an IEnumerable of known types.

Namespace:  System.Runtime.Serialization
Assembly:  System.Runtime.Serialization (in System.Runtime.Serialization.dll)

public KnownTypeAttribute(
	string methodName
)

Parameters

methodName
Type: System.String
The name of the method that returns an IEnumerable of types used when serializing or deserializing data.

This constructor uses a method name that matches a method of the class. The method returns a IEnumerable<T> of Type objects. During serialization or deserialization, the types found in the collection can be used within the root type to which the attribute is applied.

The following example uses the methodName parameter to identify a method in the type that contains an array of Type objects.


namespace KnownTypeAttributeExample
{
    using System;
    using System.Xml;
    using System.Collections.Generic;
    using System.Text;
    using System.Runtime.Serialization;
    using System.IO;
    // The constructor names the method that returns an array 
    // of types that can be used during deserialization.
    [KnownTypeAttribute("KnownTypes")]
    [DataContract]
    public class Employee
    {
        public Employee(string newFName, string newLName)
        {
            FirstName = newFName;
            LastName = newLName;
        }
        [DataMember]
        internal string FirstName;
        [DataMember]
        internal string LastName;
        [DataMember]
        internal int id;
        [DataMember]
        internal Manager Boss;

        // This method returns the array of known types.
        static Type[] KnownTypes()
        {
            return new Type[]{typeof(Manager), typeof(Employee)};
        }
    }

    [DataContract]
    public class Manager : Employee
    {
        // Call the base class's constructor.
        public Manager(string newFName, string newLName)
            : base(newFName, newLName)
        { }

        [DataMember]
        internal Employee[] Reports;

    }

    class Program
    {
        public static void Main()
        {
            try
            {
                Serialize("person1.xml");
                Deserialize("person1.xml");
            }
            catch (SerializationException se)
            {
                Console.WriteLine("{0}: {1}",
                se.Message, se.StackTrace);
            }
            finally
            {
                Console.WriteLine("Press Enter to exit....");
                Console.ReadLine();
            }
        }

        static void Serialize(string path)
        {
            Employee emp = new Employee("John", "Peoples");
            emp.id = 3001;
            Manager theBoss = new Manager("Michiyo", "Sato");
            theBoss.id = 41;
            emp.Boss = theBoss;

            DataContractSerializer ser = 
                new DataContractSerializer(typeof(Employee));

            FileStream fs =
                new FileStream(path, FileMode.OpenOrCreate);
            ser.WriteObject(fs, emp);
            fs.Close();
        }
        static void Deserialize(string path)
        {
            DataContractSerializer ser = 
                new DataContractSerializer(typeof(Employee));
            FileStream fs = new FileStream(path,
            FileMode.Open);
            Employee p = (Employee)ser.ReadObject(fs);

            Console.WriteLine("{0} {1}, id:{2}", p.FirstName,
                p.LastName, p.id);
            fs.Close();
        }
    }
}


.NET Framework

Supported in: 4, 3.5, 3.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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