I think you are on the right track but missed the business rules end of OO.
I would do the same as you - create objects for dealing with my underlying
tables. I call these objects "data access components", and normally store
them in a different folder called data. Now, you have the concept that an
event, venue, and a time slot are related. This is a business rule. In
this case, I create another object that will implement the business rules.
In your case, I might call the new object an Event object, but store it in a
different folder or name it differently so that I know it is NOT a data
access component. This object would then do any application specific
validation, and processing. The tough part with this is that you have to
make a choice where your transactions take place - in the database, or in CF
(or whatever language you're using). If you opt for placing the
transactions in the database (I'd recommend this where possible), then the
call to the stored proc should happen within one of your data access
components - the business rule component should not be dealing directly with
the database, that is not it's role.
Conceptually, you might end up with something like this:
EVENT Rules
- Data Access Components
- Event data access component
- Venue data access component
- Timeslot data access component
- Specialized data access component (if needed).
- Business functions
- Save Event (-which might call individual functions on the member
data components)
Not sure if this is entirely clear, but hopefully it get's you moving in the
right direction...
Shawn
-----Original Message-----
From: Jim Davis [mailto:[EMAIL PROTECTED]
Sent: Thursday, September 18, 2003 1:14 PM
To: CF-Talk
Subject: OO modeling Hell
Sorry - thismay be semi-off topic (but then again it may be semi-on
topic - possibly even flat-out on topic!)
I'm working on modeling an existing procedural system (first built in CF
4) to CFMX and want to implement "correctly" (as possible) in an OO/CFC
framework.
I'm doing the static model now and have run into a conceptual problem.
Hoping for some opinions.
The system is an event planner for a large, single-day festival.
Stripping it down to the problem domain we have a database model with
three tables:
1) "Events": All the events taking place.
2) "Venue": All the locations that events can take place at.
3) "TimeSlots": All of the tied begin/end times for events. For example
"10:00-14:00", "10:00-11:00", "13:00-15:00", etc
In the DB this works well. "Events" and "TimeSlots" are joined with
"EventsToTimeSlots" (many to many). You can then query easily based on
start-time, end-time, or duration. "EventsToTimeSlots" also links to
"Venues". This allows an event to occur at any time and each time to be
located at a distinct venue.
So we may have a dance troupe appearing at 8pm-10pm at the Boston Ballet
bulding, then from 11pm-midnight at Boston Common.
When converting this to an object model I naturally began by considering
"Event", "Venue" and "TimeSlot" as objects. (Right?) My issue is how
to deal with the three-part join.
I have, for example, an array in each TimeSlot object containing a
references to all the events taking place. I can then loop through all
the timeslots and collect all the events taking place at any time or of
a certain duration. Sorting this kind of return may be a problem, but
not (I think) big one.
I can also have an array of references in each Venue object to events
taking place there. Lastly (I'm guessing) can have a two-dimensional
array of TimeSlot and Venue references in each Event linking each
timeslot to a venue.
Is this the best way to do this?
Should I instead some "sub object" that directly represents my join
table that contains a reference to an Event, TimeSlot and Venue? Maybe
called "Schedule" or something?
Or should each TimeSlot object contain a single reference to an Event
and Venue and just have a lot of duplicate StartTime/EndTimes? (I don't
think I would as it would be more difficult to present the details of a
single event.)
Does this whole "Timeslot" idea just not fit in OO as well as it does in
the relational system?
In the end the model I want should allow each event object to quickly
get the venue and time for each performance (perhaps that goes without
saying) but I also want to be able to easily list "All events at Venue",
"All events at TimeSlot" and "All events at StartTime/EndTime".
Thanks in adavance,
Jim Davis
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