CODEWITHSUNDEEP
vb.netlinqlinq-to-entities
Dewey
Dewey

Reputation: 892

Linq Group By multiple properties in VB.Net

I want to Group By on a List using VB.Net. Seems simple but I can't make it work. I've tried:

Dim groupedEmails = saEmails.GroupBy(Function(m) New With {m.Property1, m.Property2, m.Property3.SubProperty1})

I have 6 items in saEmails and two of the items have the same Property1, Property2 and Property3. Unfortunately, at runtime I'm still getting 6 items in groupedEmails even though my grouping should reduce that count to 5.

I've tried the statement without the "New With" (it still compiles) but the result is the same. I also can't get Linq to Entities ("From mail in saEmails...") to accept my use of the keyword "Group". I have Imported System.Linq.

I would also be happy with a working use of .ToLookup().

The entities are similar to this:

    Namespace Something
    <DataContract()>
    Public Class SAEmail

        <DataMember()>
        Public Property Property1 As Integer

        <DataMember()>
        Public Property Property2 As String

        <DataMember()>
        Public Property Property3 As Blah

        <DataMember()>
        Public Property Property4 As String

    Public Overrides Function Equals(obj As Object) As Boolean

        If obj Is Nothing OrElse Not Me.GetType() Is obj.GetType() Then
            Return False
        End If

        Dim email As SAEmail = CType(obj, SAEmail)
        Return Property1 = email.Property1 _
            AndAlso Property2 = email.Property2 _
            AndAlso Property1.SubProperty1 = email.Property3.SubProperty1

    End Function

    Public Overrides Function GetHashCode() As Integer
        Return CInt(CLng(Property1) Xor CLng(Property2) Xor CLng(Property3.SubProperty1))
    End Function

    End Class

    <DataContract()>
    Public Class Blah

        <DataMember()>
        Public Property SubProperty1 As Integer

        <DataMember()>
        Public Property SubProperty2 As String

    End Class
End Namespace

Ideas?

Upvotes: 0

Views: 664

Answers (1)

Craig Johnson
Craig Johnson

Reputation: 754

How about creating a composite grouping key?

Dim groupedEmails = saEmails.GroupBy(Function(m) String.Format("{0}:{1}:{2}", m.Property1, m.Property2, m.Property3.SubProperty1))

Or, using an interpolated string when VB14 is released in a few weeks!:

Dim groupedEmails = saEmails.GroupBy(Function(m) $"{m.Property1}:{m.Property2}:{m.Property3.SubProperty1)}")

Upvotes: 1

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