November 2000 - Zope-Dev

ZPetterns implementation qustions
by Itai Tavor 05 Dec '00

05 Dec '00

Hi, I'm trying to figure out the right way to implement a set of classes and roles in ZPatterns. I asked some questions about this a while ago, and then went away and did some learning, but I'm stuck again and I'm afraid I need to ask more questions. I have two types of actors - Person (with properties name, phone, email, password) and Organization (with properties name, phone, fax, business_number). I also have two participants - Customer and Reseller. Each participant can be either a Person or an Organization. The participants can fill several roles, like OrderingEntities, BillableEntities, etc. Starting from the bottom, I create a Specialist for each role, each one with two virtual Racks - customerRack and ResellerRack, so I can refer to an OrderingEntity without caring if it's a Reseller or Customer. My problem is in implementing the Participant Specialists and storing Participant and Actor classes. Do I create Specialists for the Actors? It seems to me that since there is either one Person or one Organization per Customer, then the actor object should be created in the Customers Specialist. So Customers will have 3 Racks - defaultRack (using Customer object), personRack (using Person object) and organizationRack (using Organization object). Does this make sense? If this is a good way to do it, how do I handle creating and accessing the Person and Organization objects? Do I call personRack.newItem(newCustomerId) in the script that creates the customer? Or do I somehow do it in a SkinScript in defaultRack? And how do I get to the Person data? With an attribute provider? Or in the SkinScript: WITH personRack.getItem(self.id) COMPUTE name=name, phone=phone, email=email, password=password, personObject=RESULT) Also, if Actors are stored in the Specialists that implement the roles they participate as, there is no place to store methods that are common to an Actor regardless of role - for example, a method that checks if a password is secure enough and called when adding a Person object. So I either duplicate these methods in every Participant Specialist, or create more Specialists - which seems like a waste either way. Another problem is how to edit these objects - if I have a form which includes fields for a Customer properties and for the properties of the Person object linked to that Customer, can I change the Person object from the Customer SkinScript? I don't think I can do this: WHEN OBJECT CHANGED STORE name, password USING personObject.propertysheets.manage_changeProperties(name=self.name, password=self.password) Right? Because name and password are not properties on the Customer DataSkin. So I have to call person.manage_changeProperties(...) in the method that changes Customer... it seems to me that I always end up doing object connections work in methods and the SkinScript can't help with anything :( Hope this is not too convoluted...I'd really appreciate any help anyone can offer. The existing ZPatterns examples all deal with fairly straightforward situations, but it's the more complex class relationships where the bears and tigers are hiding :) Itai -- Itai Tavor "Je sautille, donc je suis." C3Works itai(a)c3works.com - Kermit the Frog "If you haven't got your health, you haven't got anything"

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Re: [Zope-dev] RFC: Python/Zope Interfaces
by Dieter Maurer 30 Nov '00

30 Nov '00

Michel Pelletier writes: > Also, defining the interface seperately keep the two things apart, > impementation and interface, and doesn't allow you to sneak in a new > method unless you also sneak it into the interface, thus making a > stronger "contract" with the user. I am a bit astonished by this statement: I know the "design by contract" concept from Bertrand Meyer, the Eiffel developper. In Eiffel, essential parts of the contract, among others method prototype, pre- and post-conditions as well as invariants are build directly into the language. A documentation tool extracts these parts from the source to generate the interface, for people that are only interested in how to use the class/method. Programms can be executed in a way, that the various (executable) contract parts can be checked at runtime. *THIS* provides for quite a strong contract. I cannot see, why the separation of interface and implementation should make the contract stronger. I do see, however, that it makes it more likely to be broken by the implementation. It is a very good thing to have the specification very near to the implementation -- as a permanent guide to the implementor. It is even better, when big parts of the specification becomes part of the executable code (as is the case for Eiffel's pre- and post-conditions). If you want to prevent your implementors to change the interface specification, generate the interface for the implementation and compare against your master copy. In my view, it is better to have a somewhat "weaker" contract that is met by the partners than a "stronger" contract that is violated. Or, to say it differently, it is more essential the a system's documentation describes faithfully what is rather than what should be (but is not). Dieter

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Re: [Zope-dev] Return variables from a DTML Method
by Dieter Maurer 30 Nov '00

30 Nov '00

bentzion(a)bellatlantic.net writes: > I want to change some ZClass properties by getting return results > from a DTML Method. Something like this: <dtml-call > "myzclass.propertysheets.get('Basic').manage_changeProperties(dtmlM > eth(this(),_))">. How do I get the dtmlMeth to return a Mapping? > (or should I be doing this a different way?) <dtml-return "{ 'a' : 1, 'b': 2, ....}"> There will be people that say, you should not do such things in DTML. Dieter

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ZPatterns: using PythonMethods from Skinscript
by Ulrich Eck 30 Nov '00

30 Nov '00

hi out there, this is my first posting on this list. Right now I think this is the right place to ask details about ZPatterns. I think a ZPatterns-Mailinglist should be set up, where people like me, working hard to get the "Zen of ZPatterns" can discuss questions related to USING ZPatterns. Here my first little problem: I've a db_sequence specialist who serves the Framework with db_id's for new Records like: >>> newid = db_sequence.getItem('<sequence_name>').nextid The Attribute nextid is provided by a Skinscript-Method: ________________________________________________ WITH getNextId(seq_name=self.id) COMPUTE seq_name=seq_name,nextid=_.int(nextid) ________________________________________________ "getNextId()" is a PythonMethod and uses ZSQL-Methods to compute the NextId while Locking the Table: ________________________________________________ PARAMETER: self, seq_name ________________________________________________ self.sql_Lock() nid = 1 for cur_id in self.sql_NextIdGet(seq_name=seq_name): nid = cur_id.nextid + 1 self.sql_NextIdUpdate(seq_name=seq_name,nextid=nid) break else: self.sql_NextIdCreate(seq_name=seq_name,nextid=1) self.sql_Unlock() return {'seq_name':seq_name, 'nextid':nid} # HERE'S MY PROBLEM I THINK !!!! ________________________________________________ I tried to return nearly everything expect a certain instance of a "special getNextId-Return-Object" e.g. return nid / return (seq_name,nid) ... I tried serveral ways to reach my return values in the SSMethod: ... COMPUTE nextid=nextid or nextid=self.nextid or nextid=RESULT ... Finally i tried to follow what happens during a get-call of an Attribute in the source .. no success .. except when i use some Dummy ZSQL-Method which does the following and works (but this is not the way to do it ..) "select <value> as nextid, <value> as seq_name" can someone give some advice or enlighten me about the Namespace I'm in, at SSMethods Attribute providers at execution-time ?!? My Second "little" Problem: i'm not the first one who had problems to manage data with rdbms and zpatterns. i can get Attributes through SSMethods easily and now tried to setup ADD/CHANGE/DELETED Rules to manage data. Here my SSMethod for this(getEventById/insertEvent/updateEvent are ZSQL-Methods): WITH QUERY getEventById(id=self.id) COMPUTE sid=_.int(id),name,time_start WHEN OBJECT ADDED CALL insertEvent(id=self.sid) WHEN OBJECT ADDED,CHANGED STORE sid,name,time_start USING updateEvent(id=self.sid,name=self.name,time_start=self.time_start) I access the Item through loadAttribute: "sid" I set up a ZClass derived from Dataskin which acts as Storage-Class. I call <dtml-let ni="newItem(key=db.getItem('data_event').nextid)" nips="ni.propertysheets.get('Basic')"> <dtml-var "nips.manage_changeProperties(REQUEST=REQUEST)"> </dtml-let> and get back an empty object without any attributes (propertysheet-problem??) the record in the database is created (but only because I reduced the ZSQL-Insert Method to id-parm only) this again seems to be a Problem of the namespace I'm in while the _objectAdded() ... method. - Do I need a PropertySheet when I only want to access/change/create/delete Items/Attributes from a RDBMS ?? If yes: Which one (CommonInterfaceProp/DataSkinProp) If no: how do i Access/Change my Properties ?? - and another Question related to this: Which object fires the Trigger-Event (ADDED/CHANGED/DELETED) .. is it the PropertySheet itself ??? lots of questions still there but these are the points i really tried to get working .. but i did'nt.. hope that there is an answer .. thanks in advance Ulrich Eck net-labs

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Custom Unauthorized errors...
by John Eikenberry 30 Nov '00

30 Nov '00

With all the work going on related to Zope's authentication system has there been any progress on allowing custom unauthorized errors? I'd refer to the bug id in the collector, but it seems to be down at the moment. I'm planning on using LoginManager which fixes this to a certain extent last I heard... that is it will let you use a customized unauthorized error when you know who the user is (ie. they've logged in), but not for anonymous users. Just out of curiousity (I'm looking at the source now to figure this out, but I thought it couldn't hurt to ask), why is this? The anonymous user has a user object, and so would seem to be a real user as far as the system goes. I'm tired of hacking custom unauthorized errors into zope all the time, so I'd really like to get this fixed at some point. Any thoughts as to directions to go, or dead ends to be avoided. I'll be looking into this as I find time so any help would be appreciated. -- John Eikenberry [jae(a)zhar.net - http://zhar.net] ______________________________________________________________ "A society that will trade a little liberty for a little order will deserve neither and lose both." --B. Franklin

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Using LoginManager with SQL and SkinScript
by dan＠sol.control.com 30 Nov '00

30 Nov '00

I've put up a writeup of a different way to use LoginManager with SQL that I think is a bit more in keeping with the current ZPatterns at: http://www.zope.org/Members/dlpierson/sqlLogin Any comments? (I would have set this up as a formal HowTo, but couldn't find a way to upload the contents.) Dan Pierson

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Return variables from a DTML Method
by bentzion＠bellatlantic.net 30 Nov '00

30 Nov '00

I want to change some ZClass properties by getting return results from a DTML Method. Something like this: <dtml-call "myzclass.propertysheets.get('Basic').manage_changeProperties(dtmlM eth(this(),_))">. How do I get the dtmlMeth to return a Mapping? (or should I be doing this a different way?) Thanks.

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standard_error_message does nothing?
by The Doctor What 30 Nov '00

30 Nov '00

My site uses SiteAccess2, zope 2.2.2, etc. If I got to one of my virtual hosts and enter a bogus URL, I get an error message that includes *another* error message within it (both from HTTPResponse.py's _error_html(). Example: http://docwhat.gerf.org:9673/fish I have modified _error_html() to put a comment at the very start saying where it came from. In addition, the root standard_html_message has a comment at the top and so does the /docwhat stdandard_html_message, both saying which it is. /docwhat is the folder that docwhat.gerf.org's vhost/siteroot is at. The fish url above should generate (I thought) my standard_html_message from /docwhat. I don't understand this at all. It goes against the docs in http://www.zope.org/Members/JohnC/StandardErrorMessage My site includes a view_source that works fairly well, if you want to see the various standard_html_message's. linuxasm.gerf.org is a non-siteaccessed version of my site, with no siteaccess rules. Here are the URLs: docwhat one: http://docwhat.gerf.org:9673/standard_error_message/view_source root one: http://linuxasm.gerf.org:9673/standard_error_message/view_source Thanks for any help. Ciao! -- Those are my principles. If you don't like them I have others. -- Groucho Marx The Doctor What: Second Baseman http://docwhat.gerf.org/ docwhat(a)gerf.org KF6VNC

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Re: [Zope-dev] Loginmanager and LDAP
by Phillip J. Eby 30 Nov '00

30 Nov '00

At 07:17 AM 11/28/00 +0100, Magnus Heino (Rivermen) wrote: > > >I'd like to authenticate users using LDAP and Active Directory. Zope is >running on a RH7.0 box. > >Has anyone done this, is it possible? Dunno about Active Directory or RH 7, but Ty and I use LDAP logins with LoginManager all the time on several applications. We've made a custom UserSource for ease of installation on different apps, but we originally developed it using a GenericUserSource and the ZopeLDAP product. You should be able to do the same.

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Re: [Zope-dev] OracleStorage, and possibly others
by Jim Fulton 30 Nov '00

30 Nov '00

"Phillip J. Eby" wrote: > > At 08:10 AM 11/30/00 -0500, Jim Fulton wrote: > > > >I don't think Data.fs will go away. I do expect it to be relagated to > >initial evaluation and development projects. Use of Berkely DB in > > >transactional mode requires a significant andminstration commitment. > >Log files need to be purged. Backup and recovery processes need to be in > >place. > > FWIW, Ty and I talked about using a daemonic thread in BerkeleyStorage to > run periodic checkpoints and purge logfiles. AFAIK, backups of BerkeleyDB > require only that you make a copy of all the associated files. Recovery's > a bit trickier, of course. (We never got around to implementing it because > our tests showed that BerkeleyDB didn't solve the performance issue we were > trying to solve. So we quit working on it at that point.) I don't think the storage should get involved with this. There are alot of knobs and possible policies that can be used. This is all well documented and supported by Sleepycat Software. IMO, when someone uses a Berkeley DB storage they are using Berkeley DB and should learn how to administer it. I don't think it's a good idea to try to hide this from people. Jim -- Jim Fulton mailto:jim@digicool.com Python Powered! Technical Director (888) 344-4332 http://www.python.org Digital Creations http://www.digicool.com http://www.zope.org

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