• Open Menu Close Menu
  • Apple
  • Shopping Bag
  • Apple
  • Mac
  • iPad
  • iPhone
  • Watch
  • TV
  • Music
  • Support
  • Search apple.com
  • Shopping Bag

Lists

Open Menu Close Menu
  • Terms and Conditions
  • Lists hosted on this site
  • Email the Postmaster
  • Tips for posting to public mailing lists
Re: Webobjects-dev Digest, Vol 6, Issue 949
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Webobjects-dev Digest, Vol 6, Issue 949


  • Subject: Re: Webobjects-dev Digest, Vol 6, Issue 949
  • From: Chuck Hill <email@hidden>
  • Date: Sat, 24 Oct 2009 20:40:25 -0700


On Oct 24, 2009, at 4:38 PM, Tavis McDevitt wrote:

Don:

As someone who is learning WO I can honeslty say I would have looked at your tutorials sooner if I'd known about them. They're a great addition since the best intro material I've seen so far is Apple's documentation (I've read all of it and it is still really useful and conceptual), and you help bridge the gap between thier use of deprecated tools and WOLips. (When I was done with that Chuck's book became very useful too.)

I've a question though. In your EoModelerBasics show, you made a to- one relationship from a Person entity to a Cadency entity (a title, like Jr or Sr).

I learned a new word today. :-)


I get it. You also made the inverse to-many relationship from Cadency to Person. I don't get that. If I assume that I will never traverse an inverse relationship (I will never want to know what people have a Jr in their signature), do I have to model the inverse relationship? I've been skipping that.

To clarify what Miguel said, I would never model that particular relationship. If you every need it, you can just fetch them. If you model this, once you get up to tens or hundreds of thousands of row, doing an addObjectToBothSidesOfRelationshipWithKey is going to fetch a LARGE number of rows for no reason.


For things like, er, Cadency, I'd consider NOT modelling it at all. I think Wonder has some magic to turn codes (e.g. 0, 1, 2 etc.) into POJO when you fetch.


One more question while I'm at it. What's the best way to model a linked list? I've thought of putting list items in a table with an inbred relationship that links to other list items. My concern is that to retrieve the list at once I'd have to have many trips to the database, because in a single fault I will only know the root item in the list, and after each succesive fetch will only have a reference to one more item. I don't know much about stored procedures; can one be written to fetch the entire list?

I've used self referencing relationships before, but not for a linked list. I've only used them when I could fetch all the data at once or when the relationships only went a few levels. As you point out, more than that will cause performance problems. If list order is your concern, then Miguel gave you a good answer. If you are after something else, we will need more details.



Chuck


Message: 8
Date: Sat, 24 Oct 2009 14:57:11 -0400
From: Don Lindsay <email@hidden>
Subject: Re: 2009 surveys results
To: undisclosed-recipients: ;
Cc: webobjects Apple <email@hidden>
Message-ID: <email@hidden>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes

I agree with Robert, I created several tutorials for WebObjects as
well as an installer for windows and linux.  This is something that I
use my spare time to support.

Based on my review of hits to the tutorials, they are rarely
accessed.  If they were used more, I would create more of them.

The tutorials I made are available at:  http://web.me.com/pccdonl/tutorials/WoLipsInstall.htm
  as is the installer.  (I havent updated the installer in a couple
of months)

Don

_______________________________________________
Do not post admin requests to the list. They will be ignored.
Webobjects-dev mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden

-- Chuck Hill Senior Consultant / VP Development

Practical WebObjects - for developers who want to increase their overall knowledge of WebObjects or who are trying to solve specific problems.
http://www.global-village.net/products/practical_webobjects








_______________________________________________
Do not post admin requests to the list. They will be ignored.
Webobjects-dev mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden


  • Follow-Ups:
    • Re: 2009 Survey Results
      • From: Tavis McDevitt <email@hidden>
References: 
 >Re: Webobjects-dev Digest, Vol 6, Issue 949 (From: Tavis McDevitt <email@hidden>)

  • Prev by Date: Re: 2009 surveys results
  • Next by Date: Re: 2009 surveys results
  • Previous by thread: Re: Webobjects-dev Digest, Vol 6, Issue 949
  • Next by thread: Re: 2009 Survey Results
  • Index(es):
    • Date
    • Thread