Re: EOF Inheritance, Relationships between super class and subclass
Re: EOF Inheritance, Relationships between super class and subclass
- Subject: Re: EOF Inheritance, Relationships between super class and subclass
- From: "Jerry W. Walker" <email@hidden>
- Date: Sun, 2 Jul 2006 23:04:49 -0400
Hi, G. Brown,
Although there are a couple known problems with EO inheritance,
generally, it is fairly reliable. I don't see any problems with using
inheritance here. I'm presuming definitions something like the
following:
PatientAlias
name
address
city
state
zip
testResults
validations
verifiedPatient
...
VerifiedPatient extends PatientAlias
patientAliases
insurance
....
I don't see why this wouldn't work fine. You could either have the
verifiedPatient attribute on the VerifiedPatient record set to null
(in which case, the patientAliases to-many relationship on the
VerifiedPatient would not include the self reference) or be set to
point back to itself (in which case, the patientAliases to-many
relationship would include it). I don't see any particular problems
with either approach so long as you set up your EOModel consistently
and appropriately.
Whether you include the back reference or not, you could use
addObjectToBothSidesOfRelationship() throughout to establish the
relationships.
Hope this helps.
Regards,
Jerry
On Jul 2, 2006, at 5:27 PM, Mr. G Brown wrote:
Yes,
A VerifiedPatient would be a subclass of a PatientAlias (from a
Java perspective); they would have many properties in common,
methods, validations, etc. A VerifiedPatient would link (from a SQL
perspective) to many PatientAliases, and under each PatientAlias
there would then be links to information entered under that alias.
But from what I have read, there are bugs with inheritance, and it
might be better to just duplicate the common properties and
methods.....
On Jul 2, 2006, at 4:39 PM, Ken Anderson wrote:
Mr G. Brown,
I think it would be necessary to understand your object model a
little more before being able to recommend if/how to use
inheritance. At the moment, I really don't see any entities you
have that are good candidates for inheritance, unless I'm
misunderstanding your problem. It seems to me like you need a
Patient entity and a PatientAlias entity, related Patient <->>
PatientAlias.
Yes, but from a Jave perspective the Patient is a subclass of
PatientAlias, or should be...
Can you please give us some more detail?
Well the above is the gist of it...
Consider Mary Smith, who has some tests, then next year is Mary
Doe, and gets more tests, then the next year is Mary Smith again,
who gets more tests, then the following year is Mary Rogers. Now
find all the info for Mary Smith/Doe/Smith/Rogers. And yes, an ID
number would work...in an ideal world where there weren't any typos
or mistakes with that property.
Ken
On Jul 2, 2006, at 1:01 PM, Mr. G Brown wrote:
Hello,
I have a few questions about inheritance, thanks if anybody can
help.
The parent class would be a Patient, or more accurately, a
PatientAlias, because with typos, name changes (marriage or
otherwise) information about the same human being could appear,
does appear, under several PatientAliases.
The derived class would be a VerifiedPatient, which would be like
a PatientAlias, but with some more info.
A VerifiedPatient does have a "to many" relationship to
PatientAliases, and a PaitentAlias has a "to one" relationship
with a VerifiedPatient.
Now it would be nice to extend a PatientAlias class to a
VerifiedPatient class, BUT with the "to many" and "to one"
relationships will that work? or will that cause problems? Does
EOgenerator work with inheritance? And what flavor of
inheritance would work best here?
Well thanks for your insights.
Mr. G Brown
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__ Jerry W. Walker,
WebObjects Developer/Instructor for High Performance Industrial
Strength Internet Enabled Systems
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