On Aug 11, 2009, at 6:42 AM, Gustavo Pizano wrote:
sorry keepin gin the lsit.
On Tue, Aug 11, 2009 at 12:41 PM, Gustavo Pizano <[email protected]
> wrote:
Ahmm so I can relate Area to itslef?
interesting.. well I guess in the java class will be something like \
public Area ....
private NSArray <Area> areas...
or something like that.
Yes.
Call the Area.parentAreaId -> Area.areaId relationship "parentArea"
Call the Area.areaId -> Area.parentAreaId relationship "childAreas"
you'll have the following methods in your Area.java class:
public Area parentArea()...
public NSArray<Area> childAreas()...
(plus all the various setters and fetch stuff generated by the
templates)
another thing, but in the db I will need 2 tables isn't it? one area
and anotherone SubAreas, I hadn't made such a inheritance in a
relational world.
Do you really need inheritance? Do "sub" Areas _really_ have
differences from an Area? If so, do those differences _really_ require
you to treat them as different classes?
Inheritance should by your absolute last choice. It is needed in some
situations, but you really should try to avoid using it unless it is
truly required. I've often used inheritance too quickly and ended up
painting myself into a corner later in the development process and
wishing I had used a different design pattern to meet my needs instead
of inheritance.
If you really do need inheritance, then you need to pick from the 3
different strategies for creating the inheritance structure in the DB.
Single-Table Inheritance (most likely the best choice, one table that
holds data for the super and all subclasses), Vertical Inheritance
(one table for the super, one table for each sublcass. Be forwarned,
it's not often used so there is not a lot of support out there. Hi
Lachlan) or Horizontal Inheritance (one table for each subclass).
HTH,
Dave
G.
On Tue, Aug 11, 2009 at 12:38 PM, Stefan Klein <[email protected]
> wrote:
Hi Gustavo,
you need only one entity.
Area:
area_pk
parent_area_fk
foo
Now you build a relationship area_pk <->> parent_area_fk.
So each area can have many 'subareas' while one are has only one
parent area.
Stefan
Gustavo Pizano schrieb:
Hello Im doing an eomodel.. .and I have an entity called Area, and
SubArea, for me an area can have many subareas, but subarea its an
area itself also..
so its like Area <- >>SubArea.
Now what are the implications of defyning Area with its properties,
and then SubArea and put as parent Area?... I see that inside Area
Entity there is SubArea Entity also... but I guess this doesn't
guaranties me the to-many relationship between the 2 entities isn't
it?do I still have t defying the relationship?
Thanks
Gustavo
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Webobjects-dev mailing list ([email protected])
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/webobjects-dev/stefan.klein%40buero-sde.de
This email sent to [email protected]
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Webobjects-dev mailing list ([email protected])
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/webobjects-dev/webobjects%40avendasora.com
This email sent to [email protected]
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Webobjects-dev mailing list ([email protected])
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com
This email sent to [email protected]
