Generic Dal in WCF using VB.NET

Mahadesh Mahalingappa
Nov 09, 2012
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In this article I would just give a tip on how to improve on the Generic DAL which we just finished in this Series . I already posted the C# code of the Service Layer.

To see: http://www.c-sharpcorner.com/Authors/Mahadesh/mahadesh-mahalingappa.aspx

For Visual Basic Guys I am doing it now .

Though the Generic DAl which we had designed worked well. We still were not able to create a 100% Generic Solution in the previous article . Inorder to achieve a 100% Generic Method , We need to take the Help of Reflection . We would need to call the method CreateObjectSet using Reflection .

This is how the Service Layer needs to be modified .

Imports GenericDAL
Imports System.Data.Objects
Imports System.Reflection

' NOTE: You can use the "Rename" command on the context menu to change the class name "Service1" in code, svc and config file together.

Public Class Service1
    Implements IService1
     Public Function [Get](ByVal entity As TEntity) As TEntity Implements IService1.Get
        Dim x1 As IEnumerable(Of TEntity) = GetObjectSet(entity)
        Return x1.First()
   End Function

     Public Function GetObjectSet(ByVal entity As TEntity) As Object
        Dim context As New MCSEntities()
        Dim typeArgs As Type() = {ObjectContext.GetObjectType(entity.[GetType]())}
        Dim typObjectContext As Type = context.[GetType]()
        Dim NoParams As Type() = {}
        Dim meth As MethodInfo = typObjectContext.GetMethod("CreateObjectSet", NoParams)
        Dim methGeneric As MethodInfo = meth.MakeGenericMethod(typeArgs)
          Return methGeneric.Invoke(context, Nothing)
    End Function
End Class

The Service Contract Looks as below :

Imports GenericDAL
<ServiceContract()>
Public Interface IService1
    <OperationContract()> _
    Function [Get](ByVal entity As TEntity) As TEntity
End Interface
The TEntity Class looks as below :
Imports System.Runtime.Serialization
Imports System.Data.Objects.DataClasses
<KnownType(GetType(MCS_CR_Company))> _
<KnownType(GetType(MCS_CR_Product))> _
<Serializable()> _
<DataContractAttribute(IsReference:=True)> _
Public Class TEntity
    Inherits EntityObject
End Class

Client Code :

Imports Client.DataServiceReference
Module Module1
      Sub Main()
        Dim client As New Service1Client()
        Dim entity As TEntity = New Article()
      Dim company As TEntity = client.Get(entity)
          Console.ReadKey()
      End Sub
End Module