[Zope-dev] Referencial Integrity in ZCatalogs

[Roché Compaan]

Have a look at Archetypes, it does what you want.

	http://sourceforge.net/projects/archetypes

-- 
Roché Compaan
Upfront Systems                 http://www.upfrontsystems.co.za


Santi Camps wrote:
> Hi all,
> 
> I've been developing database oriented applications for about 10 years, 
> using zope with Relation DDBB for one year and a half, and just one year 
> using Zope with ZODB in my applications.   At this point, I can see a 
> lot of advantatges of use ZODB with Zope, but there are some points 
> where the relational model was more useful to me. In fact, the main 
> problem in my applications are relationships.   In a relational world, 
> you can specify relations using foreign keys, and also say what action 
> should be done on delete or on update (no action, set null, restrict, 
> cascade, set default).   This is very useful developing business 
> oriented applications. Using ZODB some of these relations can be done 
> using containment:   If A contains B, this is the same of having a 
> relation "1->N on delete cascade"
> Another case is to use a Relation Manager.   I've implemented and object 
> Relation that is deleted when some of the two related objects are (using 
> manage_beforeDelete).  This is the same that a relation "M -> N on 
> delete cascade"
> The third case I've been implemented, and the one giving me more 
> problems, is to have a property referencing another object (path or 
> UID).  If the referenced object is dropped, the referer has problems
> 
> I work a lot with ZCatalogs, using one catalog for each meta_type of 
> objects, so for me catalogs are the most similar thing to a "Table".   
> I'm thinking that could be very useful to implement some basic 
> referencial integrity in ZCatalogs.   Just being able to define primary 
> keys and some simple types of foreign keys we will have on Zope the best 
> of two worlds.   Seeing code of ZCatalog product it seems not to be very 
> difficult to implement, adding some validations on catalog_object and 
> uncatalog_object methods.   Of course, all these should be optional.   I 
> no Primary Keys neither Foreign Keys are defined, catalogs should work 
> exactly like until now.
> 
> What do you think about this ?  If nobody convince me that this is a 
> stupid work, I will try to implement it.   In this case, what's the 
> better way to provide the code ?  A patch for ZCatalog ?  Or a new 
> Product IntegrityZCatalog inheriting from ZCatalog ?
> 
> Thanks
> 
> Santi Camps
> 
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