Re: Need example binding UI to BL to DL
From: Nick Malik [Microsoft] (nickmalik_at_hotmail.nospam.com)
Date: 12/30/04
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Date: Thu, 30 Dec 2004 16:28:19 GMT
Actually, Frank, the article he pointed to is about a code block that is
available for download along with a number of samples that show how to use
it. It looks like a reasonable approach to the problem you describe. The
block is a straight-forward implementation of the Model-View-Controller
pattern.
In addition, you can also look at NHibernate.
(http://nhibernate.sourceforge.net/) It may suit your needs a little
better.
Your post describes a great deal of frustration in what is called
Object-Relational mapping or Object-Relational Impedence. The Java world
attacked this problem by creating the Hibernate framework that will take a
config file, along with a module that can examine your code, and the
framework does all the work for you of querying the database, retrieving the
data, moving the data in and out of collections of objects of specific
types, and persisting the data back to the database. The amount of code you
have to write is small. If you use a tool like NHibernate, your data layer
becomes trivial, and you can go ahead and put the logic you want in your
business layer.
The objects you'd create would work well for both windows forms and the web.
HTH,
--
--- Nick Malik [Microsoft]
MCSD, CFPS, Certified Scrummaster
http://blogs.msdn.com/nickmalik
Disclaimer: Opinions expressed in this forum are my own, and not
representative of my employer.
I do not answer questions on behalf of my employer. I'm just a
programmer helping programmers.
--
"Frank Romano" <buzzoff@spam.no> wrote in message
news:OV9Tknn7EHA.3908@TK2MSFTNGP12.phx.gbl...
> Hi, Ken. Thanks for getting back but this doesn't help. The article you
> pointed to is about theory and architecture, not actual implementation.
>
> Any other ideas?
>
> Thanks,
> Frank
>
>
> "Ken Tucker [MVP]" <vb2ae@bellsouth.net> wrote in message
> news:%23fsCAhf7EHA.1188@tk2msftngp13.phx.gbl...
> > Hi,
> >
> > Maybe this will help.
> >
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnbda/html/uip.asp
> >
> > Ken
> > ----------------
> > "Frank Romano" <buzzoff@spam.no> wrote in message
> > news:%237OcK3b7EHA.208@TK2MSFTNGP12.phx.gbl...
> > Hey, everyone. I have an application that was written in VB6 that I
have
> > to
> > rewrite in VB.NET 2003 and I am completely lost. I have tried finding
> > answers to my questions in MSDN and the newsgroups, but I'm only finding
> > bits and pieces that just don't add up for me because I must not be
using
> > the right search words. Anyway here is what I need help with.
> >
> > The existing app would best be described as being a "customer-orders"
> > type.
> > It uses classes to represent the various business objects. The main
ones
> > are compound objects, the containing object having details specific to a
> > single instance (such as a "customer" or an "order"), with embedded
"typed
> > collection" classes that would be like "orders for this customer" or
> > "items
> > for this order". The UI lets the user specify a particular "Parent ID"
> > which is passed to the respective collection's "Item" method and gets
back
> > the desired instance of that type. The collection class reads the
> > necessary
> > details from the database and assigns the values to the instance
> > properties.
> > Once populated, the UI interacts with the object and the contained
> > objects,
> > not the database. Conversely, when told to save the changes, the class
> > reads the values out of the instance and writes them back to the
database.
> > The embedded classes and their data are implemented as typed
collections,
> > there is no data binding being used. The UI isn't binding either.
Forms
> > have methods that assign the values from the instance to the various
> > controls (text boxes, listviews, etc.) or scrapes changes from the UI
back
> > into a particular object. It works, but it is really cumbersome and
> > inefficient, particularly since we want to be able to use these business
> > and
> > data layer objects for both Windows clients and eventually web browser
> > clients.
> >
> > What I have to do is rewrite the app so that the UI can bind to the
> > business
> > objects and the business objects in turn bind to the data layer. I
> > understand the basics of the vbobjectbinding example, but I am
completely
> > confused about how I can in turn bind the class to its data source
without
> > having to resort to the existing app's approach of manually assigning
the
> > property values to the datarows or query parameters. I guess what I
want
> > to
> > do is something like this:
> >
> > UI passes a specific ID (i.e., "Customer Number") to the Item property
of
> > a
> > business layer object. That in turn executes a method like
> > "GetCustomerAndOrders(ByVal CustomerID As Integer)" which runs a
parameter
> > query that populates a typed dataset with the details related to that ID
> > (a
> > datatable containing just the single Customer record, and another
> > datatable
> > containing the Orders for that Customer ID. Once the dataset is ready,
> > instead of doing assignments to properties (ThisCustomer.CoName =
> > ds.customer.cust_co_name) or walking the Orders table and manually
> > constructing the collection of order headers (For Each dr in
> > ds.orders.rows
> > ... ThisCustomer.Orders.Add(New OrderInfo(...)), I want to be able to
bind
> > the properties directly to the underlying datarow. In the case of the
> > "orders" collection, I want the collection to be complex-bound and
> > serve-up
> > instances of "OrderInfo". When the user sends changes back, I want to
be
> > able to just execute the Update methods without having to scrape the
> > values
> > from the instance objects. I imagine this would require storing the
> > dataset
> > with the parent object, and using references to the corresponding
> > datatables.
> >
> > What totally confuses me is what I should be specifying for the Inherits
> > and/or Implements directives to make this work, and then how to write
the
> > binding routines that will pull this off. I have come across partial
> > examples that say use IBindingList or ArrayList or a specialized
> > collection,
> > but these are all focused on the UI binding and don't show anything
about
> > how to propagate binding to a dataset. There are also a number of
> > examples
> > that touch on this using built-in capabilities of VS2005/ADO.NET 2.0,
but
> > that's of no help to me in the present.
> >
> > Can someone please point me to a comprehensive example of how create a
> > Windows Forms application to do this using VB 2003 and ADO.NET 1.1?
> > Thanks.
> >
> >
> >
>
>
- Next message: Nick Malik [Microsoft]: "Re: Calling functions with hardcoded fieldnames?"
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- In reply to: Frank Romano: "Re: Need example binding UI to BL to DL"
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