[DDC-265] Possibility for Nested Inheritance Created: 21/Jan/10  Updated: 16/Jan/13

Status: Open
Project: Doctrine 2 - ORM
Component/s: ORM
Affects Version/s: None
Fix Version/s: None
Security Level: All

Type: New Feature Priority: Major
Reporter: Michael F├╝rmann Assignee: Roman S. Borschel
Resolution: Unresolved Votes: 0
Labels: None

Issue Links:
Duplicate
duplicates DDC-138 Allow for mixed inheritance mapping Open

 Description   

It would be great if Doctrine had the possibility to define a further inharitance in a subclass.

Example:
There is a class DataObject managing things like created- and lastedit-
timestamps, archiving objects before updates, ...
One of the sub-objects is Content.
There are several types of content.
Written directly to a database field, read from a textfile on server,
executed php file on server, loaded from another server via xmlrpc and
so on.

I'd like to use a single table inheritance to map all information of
the different content objects in one table.
If I understand the model right the only alternate solution would be
to write each single content object to the discriminator map of
DataObject.



 Comments   
Comment by Benjamin Eberlei [ 21/Jan/10 ]

The DataObject you describe is a no-go for Doctrine 2. Its just a very bad practice.

Inheritance Mapping is for REAL inheritance only, otherwise you shouldnt go with a relational database in the first place.

You should use the Event system for such changes, it offers you roughly the same possibilities and keeps you from having to use inheritance mapping. You could still create an abstract data object and define the fields that will be used in each "implementation" and then in events do something like:

if ($entity instanceof DataObject) {
     $entity->updated();
     $archiver->makeSnapshot($entity);
}
Comment by Jonathan H. Wage [ 20/Mar/10 ]

With this patch I think you could setup a nice similar model where you can introduce new children of this parent class and have it added to the discriminator map from the child instead of having to modify the parents mapping information.

http://www.doctrine-project.org/jira/browse/DDC-447

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