为什么WCF将Enum序列化为字符串？

Question

服务器上的代码

<DataContract(Namespace:="http://schema.aam.us.com/2010/6", Name:="TradeStatus")>
Public Enum TradeStatus

    NewOrder = 100
    SendToProvider = 101
    ProviderSubmitted = 102
    ProviderAccepted = 103
    ExecutionPending = 104
    Executed = 105
    TicketsCreated = 106 'TERMINAL STATE

End Enum

<DataContract(Namespace:="http://schema.aam.us.com/2010/6", Name:="StatusUpdate")> _
Public Class StatusUpdate

    Public Sub New(ByVal tradeStatus As TradeStatus, ByVal additionalInformation As String)
        Me.TradeStatus = tradeStatus
        Me.AdditionalInforamtion = additionalInformation
    End Sub

    <DataMember(IsRequired:=True)> _
    Public Property AdditionalInforamtion() As String

    <DataMember(IsRequired:=True)> _
    Public Property TradeStatus() As TradeStatus
End Class

生成的代码

<System.Diagnostics.DebuggerStepThroughAttribute(),  _
 System.CodeDom.Compiler.GeneratedCodeAttribute("System.Runtime.Serialization", "4.0.0.0"),  _
 System.Runtime.Serialization.DataContractAttribute(Name:="StatusUpdate", [Namespace]:="http://schema.aam.us.com/2010/6"),  _
 System.SerializableAttribute()>  _
Partial Public Class StatusUpdate
    Inherits Object
    Implements System.Runtime.Serialization.IExtensibleDataObject, System.ComponentModel.INotifyPropertyChanged

    <System.NonSerializedAttribute()>  _
    Private extensionDataField As System.Runtime.Serialization.ExtensionDataObject

    Private AdditionalInforamtionField As String

    Private TradeStatusField As String

    <Global.System.ComponentModel.BrowsableAttribute(false)>  _
    Public Property ExtensionData() As System.Runtime.Serialization.ExtensionDataObject Implements System.Runtime.Serialization.IExtensibleDataObject.ExtensionData
        Get
            Return Me.extensionDataField
        End Get
        Set
            Me.extensionDataField = value
        End Set
    End Property

    <System.Runtime.Serialization.DataMemberAttribute(IsRequired:=true)>  _
    Public Property AdditionalInforamtion() As String
        Get
            Return Me.AdditionalInforamtionField
        End Get
        Set
            If (Object.ReferenceEquals(Me.AdditionalInforamtionField, value) <> true) Then
                Me.AdditionalInforamtionField = value
                Me.RaisePropertyChanged("AdditionalInforamtion")
            End If
        End Set
    End Property

    <System.Runtime.Serialization.DataMemberAttribute(IsRequired:=true, EmitDefaultValue:=false)>  _
    Public Property TradeStatus() As String
        Get
            Return Me.TradeStatusField
        End Get
        Set
            If (Object.ReferenceEquals(Me.TradeStatusField, value) <> true) Then
                Me.TradeStatusField = value
                Me.RaisePropertyChanged("TradeStatus")
            End If
        End Set
    End Property

    Public Event PropertyChanged As System.ComponentModel.PropertyChangedEventHandler Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged

    Protected Sub RaisePropertyChanged(ByVal propertyName As String)
        Dim propertyChanged As System.ComponentModel.PropertyChangedEventHandler = Me.PropertyChangedEvent
        If (Not (propertyChanged) Is Nothing) Then
            propertyChanged(Me, New System.ComponentModel.PropertyChangedEventArgs(propertyName))
        End If
    End Sub
End Class

Answer 1

枚举默认为序列化.与primites和Collection类一样,您不需要使用[DataContract]标记它们.但是,这并不意味着WCF不允许您自定义序列化行为,因此本着互操作性的精神,您可以更改枚举的序列化方式.作为可自定义的一部分,如果使用DataContract标记它但不标记EnumMembers,则表示您正在更改默认序列化方案.有关Enum序列化的详细信息,请参阅枚举序列化

编辑:要想更多关于这一点,现在我开始想知道潜在的原因......结果证明这是WSDL的错.

默认情况下,如果不放置[DataContract],则默认情况下WCF将枚举序列化为具有[DataContract]和[EnumMembers]属性.所以如果你采取以下例子

[DataContract]
public enum FileType {
    [EnumMember]
    Text,
    [EnumMember]
    Pdf,
    [EnumMember]
    Word
}

它将生成以下WSDL

<xs:simpleType name="FileType">
  <xs:restriction base="xs:string">
    <xs:enumeration value="Text" /> 
    <xs:enumeration value="Pdf" /> 
    <xs:enumeration value="Word" /> 
  </xs:restriction>
</xs:simpleType>
<xs:element name="FileType" nillable="true" type="tns:FileType" />

所以现在如果你拿出[EnumMember]这样的属性

[DataContract]
public enum FileType {
    Text,
    Pdf,
    Word
}

您的WSDL将如下所示:

<xs:simpleType name="FileType">
  <xs:restriction base="xs:string" /> 
</xs:simpleType>
<xs:element name="FileType" nillable="true" type="tns:FileType" />

所以第二个看起来就像第一个,除了没有枚举元素.现在第二个和描述简单字符串的WSDL有什么区别？没有.这就是为什么WCF代理生成一个字符串而不是枚举.