Re: [Zope-dev] ZPatterns: persistant objects hold DataSkin-Items - KeyError: _v_dm_

2000-12-14 Thread Ulrich Eck


 I'm searching for something that handles a newItem(meta_type,key)
function
 that is provided
 from the FwCS who decides which object-type is created and gets those
 attributes from the customizer

 Just use the normal Zope "add list" to create one manually, or call the
 appropriate constructors (e.g. SomeZClass.createInObjectManager()).



after a while I think I got it now.

I use a FcWS as a Folder like usual in Zope and if i create an object
of a type which is "customized" certain attributes will be set through
the customizer. so for a database app that handles multiple tables
it isnt useful to handle with a FwCS.

First I thought there is the same "magic" as if i ..getItem() with a
specialist .. in a FwCS

Due to the Folders Rules, there can only by one object with the same id
at a time in one FwCS ..

I'll switch back to a Specialist which has many racks as data-providers
which i can choose the right one with a method that has a "meta-type"
parameter.

is this right so far ??

Ulrich Eck


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Re: [Zope-dev] ZPatterns: persistant objects hold DataSkin-Items - KeyError: _v_dm_

2000-12-14 Thread Phillip J. Eby

At 02:49 PM 12/14/00 +0100, Ulrich Eck wrote:

after a while I think I got it now.

I use a FcWS as a Folder like usual in Zope and if i create an object
of a type which is "customized" certain attributes will be set through
the customizer. 

Yes.


so for a database app that handles multiple tables
it isnt useful to handle with a FwCS.

Um, not necessarily.  You can create regular Folders under the FwCS if you
want to keep them seperate.  You can even use BTreeFolders or other
ObjectManagers, if you like.  All that's required is that they support the
ObjectManager protocol.  So you can have a folder for each meta_type.  Of
course, the primary storage of the object has to be the ZODB.


First I thought there is the same "magic" as if i ..getItem() with a
specialist .. in a FwCS

No.  The FwCS is to allow more "traditional" Zope objects to blend in data
from other sources, and/or to have trigger support.


Due to the Folders Rules, there can only by one object with the same id
at a time in one FwCS ..

Yes.   But you don't have to place the DataSkins directly under the FwCS,
they can be any number of nesting levels below it.


I'll switch back to a Specialist which has many racks as data-providers
which i can choose the right one with a method that has a "meta-type"
parameter.

is this right so far ??

Pretty much, although I'm not sure why you want to pick by meta type, since
one of the major reasons for having a Specialist is for the rest of the
application not to know about specific meta types.


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Re: [Zope-dev] ZPatterns: persistant objects hold DataSkin-Items - KeyError: _v_dm_

2000-12-13 Thread Ulrich Eck

after one more day of source-code-reading i got that far:

When I want to use a Folder /w Customizer (FwCS) I cannot/don't need to use
Specialists.

i create a FwCS and put my 'Framework' in it.
if i want to access (get/new) an object handled by a customizer
i can ask FwCS._getDataManagerFor(client,default) for my datamanager (DM)

Do I need to implement methods like
createItem/retrieveItem/_v_itemConstructor as well
or how do i "get" my objects ??

If I have an object whose metatype is handled via
customizer/skinscript/sqlmethod it'll
probably work managing attributes ..

I'm searching for something that handles a newItem(meta_type,key) function
that is provided
from the FwCS who decides which object-type is created and gets those
attributes from the customizer

did I get this right so far ??

is there an example those newItem(meta_type,key) -
getItem(meta_type,key) ??


thanks
Ulrich Eck

 
 a) tell my TransactionManager that my attribute "ds_object" is not
pickeable
 (e.g. call it  _v_ds_object)
  and how to know if zope is restarted ?!?!?
 or
 b) store this object persistantly in my TO without showing it in the
 folder-structure but behave like a DSO
  set/get attributes through Skinscripts

 Yes.  Use a Folder w/Customization Support above your transactions.  When
 you access TO.ds_object, the DataSkin will search for a DataManager and
 find one in the FwCS, assuming you've configured one.

 Note that this is mutually exlcusive to using Specialists to store the
 DataSkins.  In the FwCS approach, you configure Customizers for each
 meta_type of objects you'll be dealing with.  You can then give them
 SkinScript, etc. to configure behaviors.  Also, this approach requires use
 of the ZODB to store at least the "shell" (class reference and ID) of each
 DataSkin.  But since your application is ZODB-dependent already, this is
 not an issue.

 Personally, I'd suggest that if you want to take advantage of ZPatterns'
 database independence, you should instead restructure your app so that
your
 TO's are themselves DataSkins, stored in a Specialist.  Right now, you
have
 a very heavy dependence on the ZODB.



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Re: [Zope-dev] ZPatterns: persistant objects hold DataSkin-Items - KeyError: _v_dm_

2000-12-13 Thread Phillip J. Eby

At 06:31 PM 12/13/00 +0100, Ulrich Eck wrote:
after one more day of source-code-reading i got that far:

When I want to use a Folder /w Customizer (FwCS) I cannot/don't need to use
Specialists.

Not to store your objects, no.  You can still use Specialists to
concentrate search methods, constructors, UI snippets, and the like.
Typically, in that configuration some of your Specialists may contain (or
be) ZCatalogs which index selected objects from your FwCS hierarchy.


i create a FwCS and put my 'Framework' in it.
if i want to access (get/new) an object handled by a customizer
i can ask FwCS._getDataManagerFor(client,default) for my datamanager (DM)

Not necessary.  If you retrieve your DataSkin as an attribute of its
container, the DataSkin __of__ method will automatically find and bind the
DataManager (assuming you're not using some class that overrides __of__).


Do I need to implement methods like
createItem/retrieveItem/_v_itemConstructor as well
or how do i "get" my objects ??

Just retrieve the objects from their containers in the normal Zope way.
Ditto for creation - use the standard way of constructing objects in an
ObjectManager.


If I have an object whose metatype is handled via
customizer/skinscript/sqlmethod it'll
probably work managing attributes ..

Yes, it should.  Likewise triggers, if you want to set up cataloging triggers.


I'm searching for something that handles a newItem(meta_type,key) function
that is provided
from the FwCS who decides which object-type is created and gets those
attributes from the customizer

Just use the normal Zope "add list" to create one manually, or call the
appropriate constructors (e.g. SomeZClass.createInObjectManager()).


is there an example those newItem(meta_type,key) -
getItem(meta_type,key) ??

You want examples?  You forget, this is ZPatterns.  ;)  Seriously, look for
examples of how to create an object by meta_type in a Zope ObjectManager.


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Re: [Zope-dev] ZPatterns: persistant objects hold DataSkin-Items - KeyError: _v_dm_

2000-12-13 Thread weblabs


 Not necessary.  If you retrieve your DataSkin as an attribute of its
 container, the DataSkin __of__ method will automatically find and bind the
 DataManager (assuming you're not using some class that overrides __of__).


ok i've gone all through the source searching for a method
to get an object of a meta-type with key ...

when I call FwCS.getOb(id) then i get back an object with ??meta-type??
if I have different Customizers all serving one meta-type ???

example:
I Have a Customizer for an EventClass and another for LocationClass

they're both stored in an database using an unique int as PrimaryKey

when i call getOb(1) how should my FwCS know which one it should
give back ??

 Just retrieve the objects from their containers in the normal Zope way.
 Ditto for creation - use the standard way of constructing objects in an
 ObjectManager.
 Just use the normal Zope "add list" to create one manually, or call the
 appropriate constructors (e.g. SomeZClass.createInObjectManager()).


Yes, if i create an object and call FwCS._setObject(id,ob) the FwCS can
choose the right place to store the object
e.g. if properly configured using a Customizer with SSMethod


 is there an example those newItem(meta_type,key) -
 getItem(meta_type,key) ??

 You want examples?  You forget, this is ZPatterns.  ;)  Seriously, look
for
 examples of how to create an object by meta_type in a Zope ObjectManager.


just the one snippet of code which how to serve the problem i described ..

thanks again for your appropriate help

Ulrich Eck


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