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At the specific request of Ibexa we are changing this projects name to "Exponential" or "Exponential (CMS)" effective as of August, 11th 2025.
This project is not associated with the original eZ Publish software or its original developer, eZ Systems or Ibexa".

Building Class Hierarchies

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Tristan Koen	Thursday 12 June 2003 6:50:04 am Hi All, Is it possible to build class hierarchies in Exponential? If I create two classes, A and B, I want to build them so that instances of B can only have an instance of A as a parent. Very much like a foreign key relationship in an RDBMS. I could simulate this behaviour using related objects, but I cannot enforce the relationship which doesn't help.
Bruce Morrison	Thursday 12 June 2003 4:28:46 pm You can do this using permissions. Configure the system so that you can only create a class B for parents of class A. Class A acts like a "folder" having child content of class B. Cheers Bruce designIT My Blog: http://www.stuffandcontent.com/ Follow me on twitter: http://twitter.com/brucemorrison Consolidated eZ Publish Feed : http://friendfeed.com/rooms/ez-publish
Tristan Koen	Friday 13 June 2003 1:22:55 am Hi Bruce. Thanks for the answer, but you have really confused me. Where you say "Class A acts like a "folder" having child content of class B", that is exactly what I want, but I don't understand your reasoning. My understanding is as follows: 1. Create class A and class B. Class B will have a "related object" attribute that will be used to make the link to A. 2. In the admin interface, create a new role called ABhierarchy for arguments' sake. 3. The role would make the following restriction: - Module: content (you can't do all of them which makes me wonder why there is an 'All' option in the first place). - Function: create - Class: B - Section: Any - Parent Class: A 4. Apply this role to all of your users? The problem with this approach is that the restriction is placed on the user, not on the data itself. I realise that the two are somewhat equivalent from a practical point of view, but it is possible that a mis-configured user could make a big mess. If you mean something else, please explain. I am getting horribly stuck here. I would also like to have a data structure where an arbitrary number of objects of Class B can be created as children of object A. Thanks Tristan

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Tristan Koen

Thursday 12 June 2003 6:50:04 am

Hi All,

Is it possible to build class hierarchies in Exponential? If I create two classes, A and B, I want to build them so that instances of B can only have an instance of A as a parent. Very much like a foreign key relationship in an RDBMS.
I could simulate this behaviour using related objects, but I cannot enforce the relationship which doesn't help.

Bruce Morrison

Thursday 12 June 2003 4:28:46 pm

You can do this using permissions. Configure the system so that you can only create a class B for parents of class A.

Class A acts like a "folder" having child content of class B.

Cheers
Bruce
designIT

My Blog: http://www.stuffandcontent.com/
Follow me on twitter: http://twitter.com/brucemorrison
Consolidated eZ Publish Feed : http://friendfeed.com/rooms/ez-publish

Tristan Koen

Friday 13 June 2003 1:22:55 am

Hi Bruce.

Thanks for the answer, but you have really confused me. Where you say "Class A acts like a "folder" having child content of class B", that is exactly what I want, but I don't understand your reasoning.

My understanding is as follows:
1. Create class A and class B. Class B will have a "related object" attribute that will be used to make the link to A.
2. In the admin interface, create a new role called ABhierarchy for arguments' sake.
3. The role would make the following restriction:
- Module: content (you can't do all of them which makes me wonder why there is an 'All' option in the first place).
- Function: create
- Class: B
- Section: Any
- Parent Class: A
4. Apply this role to all of your users?

The problem with this approach is that the restriction is placed on the user, not on the data itself. I realise that the two are somewhat equivalent from a practical point of view, but it is possible that a mis-configured user could make a big mess. If you mean something else, please explain. I am getting horribly stuck here.

I would also like to have a data structure where an arbitrary number of objects of Class B can be created as children of object A.

Thanks

Tristan