DLL's and Circular Dependancies

rolandatem · June 12th, 2006, 02:10 AM

Hi guys I have a question on how to go about doing what Im trying to do here. I have a solution with three projects, a web project (VB), a business layer class library, and a data layer class library.

This is not exactly the objects, but here is a good way to understand my problem. Lets say I have a business class named person with three properties:

Code:

Public Class Person
   Private m_firstName As String
   Private m_lastName As String
   Private m_personID As String

   Public Property FirstName() As String
   ...
End Class

In the web project, I fill the properties from input texts (except id of course), not a problem there. However, I have a method within my business object named Load (lets just assume it's suppossed to retrieve the first person it finds in the db). Within the method I create another object from the data layer object to retrieve the data.

Code:

--from codebehind --
Dim FirstPerson As BusinessLayer.Person

FirstPerson.Load

--from the person business object--
Public Sub Load()
  Dim DLPerson As New DataLayer.PersonDataClass

  DLPerson.RetrieveFirstPerson(Me)
End Sub

--from the data layer project--
Public Class PersonDataClass
  Public Sub RetrieveFirstPerson(ByRef thePerson As BusinessLayer.Person)
     '-- pull data from db and fill object
     thePerson.FirstName = ...
     thePerson.LastName = ...
  End Sub
End Class

My issue here is that both the business layer and data layer seem to need to reference to each other, which causes a circular dependancy error. Can anyone offer a solution for this situation and still keep the architecture? Is there a way to reference the DLL's without making them all part of one project?

Thanks in advance,
Rolandatem