Статья
11/17/2011

DataMemberAttribute.IsRequired Property

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Gets or sets a value that instructs the serialization engine whether the member must be present in the serialized data when it is being deserializing.

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

Syntax

'Declaration
Public Property IsRequired As Boolean

public bool IsRequired { get; set; }

Property Value

Type: System.Boolean
true , if the member is required; otherwise, false. The default is false.

Exceptions

Exception	Condition
SerializationException	The member is not present or the member is present but it has a default value with EmitDefaultValue set to true.

Remarks

The property is used for ensuring compatibility with future versions of a type.

Examples

        ' Define the data contract.
        <DataContract(Name := "Customer", Namespace := "https://www.contoso.com")> _
        Public Class User
            Private privateName As String
            <DataMember(Name := "Last", EmitDefaultValue := True, IsRequired := True, Order := 2)> _
            Public Property Name() As String
                Get
                    Return privateName
                End Get
                Set(ByVal value As String)
                    privateName = value
                End Set
            End Property

            Private privateAge As Integer
            <DataMember(Order := 1)> _
            Public Property Age() As Integer
                Get
                    Return privateAge
                End Get
                Set(ByVal value As Integer)
                    privateAge = value
                End Set
            End Property

            Public Sub New()
            End Sub

            Public Sub New(ByVal newName As String, ByVal newAge As Integer)
                    Name = newName
                    Age = newAge
            End Sub
        End Class

        // Define the data contract.
        [DataContract(Name = "Customer" , Namespace = "https://www.contoso.com" ) ]
        public class User
        {
            [DataMember(Name = "Last" , EmitDefaultValue = true , IsRequired = true , Order = 2 )]
            public string Name { get; set; }

            [DataMember(Order = 1)]
            public int Age { get; set; }

            public User() { }

            public User(string newName, int newAge)
            {
                    Name = newName;
                    Age = newAge;
            }
        }

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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