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From: Ramsey Gurley <Ramsey.Gurley@practicemojo.com>
To: WebObjects & WOnder Development <webobjects-dev@wocommunity.org>
Subject: Re: [WO-DEV] Ideas for arbitrary to-one associations
Thread-Topic: [WO-DEV] Ideas for arbitrary to-one associations
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Date: Mon, 15 Jan 2024 23:31:39 +0000
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If you're starting from scratch, you could do this using vertical inheritan=
ce. You're sorta inventing your own vertical inheritance doing what you des=
cribe, but the entity name is on the note table instead of on the entity ta=
ble. What you would do is have one super class 'Notable' EO with a 'notes' =
to-many, and all the things you want to have related notes would subclass i=
t.

However, that's not going to work if you already have existing EOs with PK =
collisions in different tables. Vertical inheritance is also the lowest per=
formance inheritance, because it needs to do the extra joins. But on the up=
side, you could benefit from EOF knowing how to do shallow vs deep fetches =
against such an entity.

It sounds like you want graph database features in a relational database. I=
f you think you will need more tables like this note table, you could creat=
e a join table to hold all the messiness. Similar to an EOF many-to-many, y=
ou would have compound PK made of FKs to two tables, but you would add two =
more entity identifier columns, one for each FK. This would allow you to ap=
ply the same sort of anything to anything relations to all tables.

________________________________
From: WebObjects & WOnder Development on behalf of Markus Ruggiero (rucotec=
)
Sent: Monday, January 15, 2024 9:45 PM
To: WebObjects & WOnder Development
Subject: [WO-DEV] Ideas for arbitrary to-one associations

I am looking for ideas / strategies to implement the following requirement:

I want to implement something I call GeneralNote. It should be possible to =
create such a note anywhere in the application and associate it with the cu=
rrent EO, whatever this may be. Thus any EO can potentially have 0 to many =
GeneralNote objects hanging off it. One GeneralNote however is not shared, =
thus it is a real to-one relationship from GeneralNote to an EO.
It is obviously not possible (well, more like totally impractical) to model=
 a to-one relationship from GeneralNote to any/all possible destination ent=
ities in my EOModel.

Any ideas on how to do this? I want to leverage as much as possible the pow=
er of EOF. I was experimenting with code that puts the destination entity a=
nd the destination object=92s primary key value in attributes of GeneralNot=
e. I also have code that can find GlobalNote objects for an EO by using its=
 entity name and primary key for fetching. All our EOs share a common base =
class that can easily accommodate such code generically. But what if the EO=
 and a note is created at the same time? There is no primary key value yet!=
 And how can I prevent an EO from being deleted and leaving orphaned notes =
behind? Would overriding willDelete() be a good place to also delete the no=
tes? What about not allowing EO deletion when there still are notes?

Thanks for any ideas!
---markus---

________________________________
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--_000_PH7PR18MB5551DD12F10B33064C0E5CE6866C2PH7PR18MB5551namp_
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<html>
<head>
<meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3DWindows-1=
252">
<style type=3D"text/css" style=3D"display:none;"> P {margin-top:0;margin-bo=
ttom:0;} </style>
</head>
<body dir=3D"ltr">
<div class=3D"elementToProof" style=3D"font-family: Aptos, Aptos_EmbeddedFo=
nt, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 12pt; c=
olor: rgb(0, 0, 0);">
If you're starting from scratch, you could do this using vertical inheritan=
ce. You're sorta inventing your own vertical inheritance doing what you des=
cribe, but the entity name is on the note table instead of on the entity ta=
ble. What you would do is have one
 super class 'Notable' EO with a 'notes' to-many, and all the things you wa=
nt to have related notes would subclass it.</div>
<div id=3D"appendonsend"></div>
<div class=3D"elementToProof"><br>
</div>
<div class=3D"elementToProof"><span style=3D"font-family: Aptos, Aptos_Embe=
ddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 1=
2pt; color: rgb(0, 0, 0);">However, that's not going to work if you already=
 have existing EOs with PK collisions
 in different tables. Vertical inheritance is also the lowest performance i=
nheritance, because it needs to do the extra joins. But on the upside, you =
could benefit from EOF knowing how to do shallow vs deep fetches against su=
ch an entity.</span></div>
<div class=3D"elementToProof"><span style=3D"font-family: Aptos, Aptos_Embe=
ddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 1=
2pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div class=3D"elementToProof"><span style=3D"font-family: Aptos, Aptos_Embe=
ddedFont, Aptos_MSFontService, Calibri, Helvetica, sans-serif; font-size: 1=
2pt; color: rgb(0, 0, 0);">It sounds like you want graph database features =
in a relational database. If you think
 you will need more tables like this note table, you could create a join ta=
ble to hold all the messiness. Similar to an EOF many-to-many, you would ha=
ve compound PK made of FKs to two tables, but you would add two more entity=
 identifier columns, one for each
 FK. This would allow you to apply the same sort of anything to anything re=
lations to all tables.</span></div>
<div class=3D"elementToProof" style=3D"font-family: Calibri, Arial, Helveti=
ca, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<br>
</div>
<hr style=3D"display: inline-block; width: 98%;">
<span style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; font-siz=
e: 12pt; color: rgb(0, 0, 0);"><b>From:</b>&nbsp;WebObjects &amp; WOnder De=
velopment on behalf of Markus Ruggiero (rucotec)<br>
<b>Sent:</b>&nbsp;Monday, January 15, 2024 9:45 PM<br>
<b>To:</b>&nbsp;WebObjects &amp; WOnder Development<br>
<b>Subject:</b>&nbsp;[WO-DEV] Ideas for arbitrary to-one associations </spa=
n>
<div><span style=3D"font-family: Calibri, Arial, Helvetica, sans-serif; fon=
t-size: 12pt; color: rgb(0, 0, 0);"><br>
</span></div>
<div><span style=3D"font-size: 11pt;">I am looking for ideas / strategies t=
o implement the following requirement:<br>
<br>
I want to implement something I call GeneralNote. It should be possible to =
create such a note anywhere in the application and associate it with the cu=
rrent EO, whatever this may be. Thus any EO can potentially have 0 to many =
GeneralNote objects hanging off
 it. One GeneralNote however is not shared, thus it is a real to-one relati=
onship from GeneralNote to an EO.<br>
It is obviously not possible (well, more like totally impractical) to model=
 a to-one relationship from GeneralNote to any/all possible destination ent=
ities in my EOModel.<br>
<br>
Any ideas on how to do this? I want to leverage as much as possible the pow=
er of EOF. I was experimenting with code that puts the destination entity a=
nd the destination object=92s primary key value in attributes of GeneralNot=
e. I also have code that can find
 GlobalNote objects for an EO by using its entity name and primary key for =
fetching. All our EOs share a common base class that can easily accommodate=
 such code generically. But what if the EO and a note is created at the sam=
e time? There is no primary key
 value yet! And how can I prevent an EO from being deleted and leaving orph=
aned notes behind? Would overriding willDelete() be a good place to also de=
lete the notes? What about not allowing EO deletion when there still are no=
tes?<br>
<br>
Thanks for any ideas!<br>
---markus---<br>
<br>
</span></div>
<div style=3D" color:gray; font-size:9pt;  font-family: 'Calibri',sans-seri=
f;">
<hr>
<b>Confidentiality Notice:</b><i> This email, including all attachments and=
 replies thereto, are covered by the Electronic Communications Privacy Act,=
 18 U.S.C. Sections 2510-2521 and are legally privileged. This information =
is confidential, and intended only
 for the use of the individuals or entities named above. If you are not the=
 intended recipient, you are hereby notified that any disclosure, copying, =
distribution or the taking of any action in reliance on the contents of thi=
s transmitted information is strictly
 prohibited. Please notify us if you have received this transmission in err=
or. Thank you.
</i></div>
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