August 2004 - Zope-Dev

Referencial Integrity in ZCatalogs
by Santi Camps 02 Aug '04

02 Aug '04

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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Re: Zope 2.7.2, restrictedTraverse or hasattr
by Kai Hoppert 02 Aug '04

02 Aug '04

Ok found a solution in using aq_explicit Greetings Kai Hoppert ___________________________________________________ tomcom Gesellschaft für Informationstechnologie mbH Heuriedweg 14 | D-88131 Lindau Fon +49 (0)8382 975844 | Fax +49 (0)8382 975855 kai.hoppert(a)tomcom.de | http://www.tomcom.de This document should only be read by those persons to whom it is addressed and is not intended to be relied upon by any person without subsequent written confirmation of its contents. tomcom disclaims all responsibility and accepts no liability for the consequences of any person acting, or refraining from acting on the contents of this document. Any unauthorised form of dissemination, copying, disclosure, modification, distribution and/or publication of this message is strictly prohibited. For information about tomcom please contact us on +49.8382.975844 or visit our web site at www.tomcom.de

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Re: [Zope-dev] Referencial Integrity in ZCatalogs
by Roché Compaan 02 Aug '04

02 Aug '04

Santi Camps wrote: > En/na Roché Compaan ha escrit: > >> Have a look at Archetypes, it does what you want. >> >> http://sourceforge.net/projects/archetypes >> > I think you are talking about SQLStorage of Archetypes. I was actually thinking of the implementation of References, which uses the ZCatalog in manner you described. > Storing some > attributes in a Relational Database and using foreign keys in it can > solve the problem. But I have some inconveniences to use Archetypes: > 1) I don't use CMF. My applications aren't content management > applications, but business oriented applications. > 2) I like to distribute my applications without needing BBDD > installation. Just download and run. Having a relational database > backend will need some extra installation You should be able to strip away CMF dependencies, but why bother. We develop business applications with Archetypes on top of CMF. -- Roché Compaan Upfront Systems http://www.upfrontsystems.co.za

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Syslog logger broken?
by Paul Winkler 01 Aug '04

01 Aug '04

Has anybody had success with the syslog logger in Zope 2.7.0 or later? AFAICT the example in zope.conf.in is borken. See http://collector.zope.org/Zope/1425 Andreas assigned it to me, but I really have no clue how to fix it. -- Paul Winkler http://www.slinkp.com

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