Re: OOP Question

From: Jay B. Harlow [MVP - Outlook] (Jay_Harlow_MVP_at_msn.com)
Date: 06/17/04 

Date: Thu, 17 Jun 2004 09:59:04 -0500

Chris,
As OHM suggested, the OOP way to code classes for small tables of data is
System.Data.DataTable, I would consider keeping both of your DataTables in a
System.Data.DataSet, specifically a Typed DataSet.

Martin Fowler's book "Patterns of Enterprise Application Architecture" from
Addison Wesley http://www.martinfowler.com/books.html#eaa explains when you
may want to use a traditional Domain Model & Data Mapper pattern:
http://www.martinfowler.com/eaaCatalog/domainModel.html
http://www.martinfowler.com/eaaCatalog/dataMapper.html

verses a Table Module & Data Gateway patterns:
http://www.martinfowler.com/eaaCatalog/tableModule.html
http://www.martinfowler.com/eaaCatalog/tableDataGateway.html

Martin also offers a couple of other useful patterns that can be used
instead of or in conjunction with the above patterns.

FWIW: The System.Data.DataTable is an implementation of a Record Set
pattern:
http://www.martinfowler.com/eaaCatalog/recordSet.html

Rockford Lhotka's book "Expert One-on-One Visual Basic .NET Business
Objects" from A! Press provides a pre-implemented variation of Fowler's
Domain Model & Data Mapper patterns.
http://www.lhotka.net/

Generally if there is no real logic behind my domain objects, I would use
the DataSet OOM coupled with a Table Module & Data Gateway patterns. As the
classes themselves are not really living up to their potential! :-) The
Table Module & Data Gateway patterns may be implemented in a single class or
two classes. Again I would consider using a Typed DataSet.

However if there is significant logic behind my domain objects, I would then
favor the Domain Model & Data Mapper patterns.

Depending on the needs of the project I would consider Fowler's other
patterns...

Hope this helps
Jay

"Chris" <cevans@bugmonitor.com> wrote in message
news:B28Ac.9681$IF3.4920@bignews5.bellsouth.net...
> Can someone tell me the OOP way to code classes for small tables of data?
>
> For example, i'm loading several tables that will be stored in the
> current.cache of an asp.net app. One table is credit cards; another is
> countries.
>
> Do i need two classes for each of these? A parent and a child class
(similar
> to tables and table in ado.net) or is there a better way to do it?
>
> See code below...
>
> Thanks,
>
> Chris
> BugMonitor.com
>
> Public Class Category
> Public Attrib1 As Integer
> Public Attrib2 As String
> End Class
>
> Public Class Categories
> Public Shared Category As Category()
> Public Shared Count As Int16
>
> Public Shared Function GetAll() As Categories
> Dim bCategory As Category
> While dr.Read
> bCategory = New Category
> With bCategory
> .Attrib1 = val1
> .Attrib2 = val2
> End With
> al.Add(bCategory)
> Count += 1S
> End While
>
> Dim bCategories As New Categories
> bCategories.Category = DirectCast(al.ToArray(GetType(Category)),
> Category())
>
> Return bCategories
> End Function
>
> End Class
>
>