Re: Setting up horizontal inheritance
Re: Setting up horizontal inheritance
- Subject: Re: Setting up horizontal inheritance
- From: Paul Hoadley <email@hidden>
- Date: Sat, 1 Nov 2008 16:34:30 +1030
On 01/11/2008, at 3:29 PM, Lachlan Deck wrote:
On 01/11/2008, at 3:39 PM, Paul Hoadley wrote:
After finding "Subclass Entity" in Entity Modeler, and re-making
the child entity specifying horizontal inheritance, this question
remains:
On 01/11/2008, at 11:19 AM, Paul Hoadley wrote:
2. Practical WebObjects (p. 32) states that horizontal
inheritance "puts a complete copy of each entity into a separate
table". Does EOF do this for me? That is, if I use
_AMPerson.createAMPerson(), does EOF put a row in the 'amperson'
table, and a corresponding row in the 'person' table?
I've just used _AMPerson.createAMPerson() to create a new
AMPerson. There's a new row in 'amperson', and nothing in
'person'. Have I misunderstood "complete copy" here? That is,
should there be a corresponding new row in 'person', or not?
Which documentation were you reading? Horizontal inheritance is what
you said you want ... but that's not matching your expectations.
The mismatch was because I think I took "complete copy" (in Practical
WebObjects) to mean a complete copy of an inserted row rather than the
columns from parent to child table. (And the confusion before that
was because I hadn't discovered the "Subclass Entity" button in Entity
Modeler.)
Brief summary of inheritance types is as follows:
Thanks.
For both VI and STI you usually define a column in the parent (e.g.,
called entityType) that's populated on awakeFromInsertion with e.g.,
if (entityType() == null) setEntityType(entityName());
In the model you then in each child entity set the definition for
the restricting qualifier to e.g., (entityType like 'EntityName').
Thanks---I wasn't sure how to do this, which is why I chose HI in the
first place.
--
Paul.
w http://logicsquad.net/
h http://paul.hoadley.name/
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