VB.NET My class properties ends up in Circular references and thus StackOverflow exception

Question

I have 2 classess. Role and User like this

Role

Public Class Role
    Public Property RoleID As Integer
    Public Property CreatedBy As User

    Sub New()    
        If Me.CreatedBy Is Nothing Then
            Me.CreatedBy = New User()
        End If
End Class

User

Public Class User
    Public Property UserID As Integer
    Public Property Role As Role

  Public Sub New()
        If Me.Role Is Nothing Then
            Me.Role = New Role()
        End If
    End Sub
End Class

The situation is like when we create roles, we will save who created this role. So i have a CreatedBy Property of type User. Similarly when we create a User, we will mention what role the new user belongs to .So i have a property called "Role" of type "Role". This circular reference giving me StackOverflow exception as its recursive when i create an object of User class.

How do i handle this ? should i restucture my entties ? how ?

Answer 1

Create constructor overloads in each of your classes to pass the host object:

Public Class User
    Public Property UserID As Integer
    Public Property Role As Role

    Public Sub New()
        Me.Role = New Role(Me)
    End Sub
    Public Sub New(oRole As Role)
        Me.Role = Role
    End Sub
End Class

Public Class Role
    Public Property RoleID As Integer
    Public Property CreatedBy As User

    Sub New()
        Me.CreatedBy = New User(Me)
    End Sub
    Public Sub New(oUser As User)
        Me.CreatedBy = oUser
    End Sub
End Class