LINQ to XML和不同的自定义类

Dim oDocument As XDocument
oDocument = XDocument.Load("test.xml")
Dim results = (From x In oDocument.Descendants.Elements("ROW") _
   Select New With {.ApplicationName = GetApplicationName(x.Element("Message")),_
    .EventId = x.Element("EventId")}).Distinct

<ROOT>
  <ROW>
    <EventId>1</EventId>
    <CreatedTimestamp>2009-10-28</CreatedTimestamp>
    <Message>There is a bunch
    of 
  garbled
inforamtion here and I'm trying to parse out a value 
Virtual Path: /MyPath then it continues on with more junk after the
message,including extra stuff
    </Message>
    <!--Other elements removed for brevity -->
  </ROW>
  <ROW>
    <EventId>1</EventId>
    <CreatedTimestamp>2009-10-28</CreatedTimestamp>
    <Message>
      There is a bunch
      of
      garbled
      inforamtion here and I'm trying to parse out a value
      Virtual Path: /MyPath then it continues on with more junk after the
      message,including extra stuff
    </Message>
    <!--Other elements removed for brevity -->
  </ROW>
</ROOT>

Distinct不知道如何比较您的商品,因此它会返回所有未过滤的商品.您应该使用 Distinct overload that implements IEqualityComparer.这将允许您比较ApplicationName和EventId属性以确定相等性.但是,这样做意味着拥有真正的类,而不是匿名类型.该文档演示了如何以易于理解的方式实现此目的.

编辑：我能够使用IEqualityComparer和EventInfo类的样本.我添加了自己的GetApplicationName实现来测试.

Dim results = (From x In doc.Descendants.Elements("ROW") _
       Select New EventInfo With {.ApplicationName = GetApplicationName(x.Element("Message")),_
        .EventId = x.Element("EventId")})

    Console.WriteLine("Total: {0}",results.Count)
    Console.WriteLine("Distinct Total: {0}",results.Distinct.Count)
    Console.WriteLine("Distinct (w/comparer) Total: {0}",results.Distinct(New EventInfoComparer()).Count)

这输出：

Total: 2
Distinct Total: 2
Distinct (w/comparer) Total: 1

其余代码：

' EventInfo class and comparer
Private Function GetApplicationName(ByVal element As XElement)
    Return Regex.Match(element.Value,"VirtualsPath:s/(w+)").Groups(1).Value
End Function

Public Class EventInfo
    Private _applicationName As String
    Public Property ApplicationName() As String
        Get
            Return _applicationName
        End Get
        Set(ByVal value As String)
            _applicationName = value
        End Set
    End Property

    Private _eventId As Integer
    Public Property EventId() As Integer
        Get
            Return _eventId
        End Get
        Set(ByVal value As Integer)
            _eventId = value
        End Set
    End Property
End Class

Public Class EventInfoComparer
    Implements IEqualityComparer(Of EventInfo)

    Public Function Equals1(ByVal x As EventInfo,ByVal y As EventInfo) As Boolean _
        Implements IEqualityComparer(Of EventInfo).Equals

        ' Check whether the compared objects reference the same data.
        If x Is y Then Return True

        ' Check whether any of the compared objects is null.
        If x Is Nothing OrElse y Is Nothing Then Return False

        ' Check whether the EventInfos' properties are equal.
        Return (x.ApplicationName = y.ApplicationName) AndAlso (x.EventId = y.EventId)
    End Function

    Public Function GetHashCode1(ByVal eventInfo As EventInfo) As Integer _
        Implements IEqualityComparer(Of EventInfo).GetHashCode

        ' Check whether the object is null.
        If eventInfo Is Nothing Then Return 0

        ' Get the hash code for the ApplicationName field if it is not null.
        Dim hashEventInfoAppName = _
            If(eventInfo.ApplicationName Is Nothing,eventInfo.ApplicationName.GetHashCode())

        ' Get the hash code for the EventId field.
        Dim hashEventInfoId = eventInfo.EventId.GetHashCode()

        ' Calculate the hash code for the EventInfo.
        Return hashEventInfoAppName Xor hashEventInfoId
    End Function
End Class