Question

I’m doing a lab for school, and I came across something I have never done before: create a default constructor within my class. It involves creating a private field to store the connection string, and then create a default constructor that sets the connection string.

Here is what I have so far:

Public Class Appointments

    Private sqlconnection As String = ConfigurationSettings.AppSettings("ConnectionString")

    Private Property connectionstring() As String
        Get
            Return sqlconnection
        End Get
        Set(ByVal value As String)
        End Set
    End Property

    Public Sub New(ByVal sConnectionString As String)
        sqlconnection = sConnectionString
    End Sub

Am I doing this right? What is going on?

Answer 1

Looks good to me but you’ve already initilized the connection string as a private variable up top.

Are you supposed to allow someone to pass in a connection string?

Your set may need to be:

Set(ByVal value as String)
 sqlconnection = value
End Set

You also need a parameterless constructor, something which gives the string a value when you instantiate an object.

For instance the parameterless constructor could be set by a web / app config file:

public sub new()
 sqlconnection = ConfigurationSettings.AppSettings("ConnectionString")
end sub

The whole thing could be:

    Public Class Appointments 
        Private sqlconnection As String

        Private Property connectionstring() As String 
            Get 
                Return sqlconnection 
            End Get 
            Set(ByVal value As String) 
               sqlconnection = value
            End Set 
        End Property 

        Public Sub New() 
        sqlconnection = ConfigurationSettings.AppSettings("ConnectionString")
        End Sub 

        'optional you could add this but not sure how much of a fuss your professor might make it
    'parameterized constructor
    Public Sub New(ByVal sConnectionString As String) 
        sqlconnection = sConnectionString 
    End Sub 
End Class