[Modeling-users] Questions and suggestions

[Ernesto R. <er...@si...>]

Hi,

for Sebastién:
* I can only do a comparison matrix with the best-known Python OR-Mappers
because I haven't done any serious work with them. The major difference is
that the other ORMs have no query language. In Middlekit, e.g., you can use
SQL conditions, but the may not be db-independent. Strange that there is no
implementation of OQL.

To all:
after working through the docs (v.0.9-pre7) (still didn't try the package)
here are some
points:

* Dependencies: The PyPgSQL and PyGreSQL names are interchanged.  Also,
should be pypgsql

* What functions are used from 4Suite? (It's 6MB to download for Windows.)
Isn't it enough to use PyXML?

* Installation is a bit complicated, because of the dependencies. What
chances are there to create a complete install file (perhaps excluding
db-adaptors) for some of the mile-stone versions?

* Although the inheritance mapping is described, I can't see out of the docs
if a relations may map to different tables (say Animals and Humans). This is
because the class has to be stored with the foreign key. (See ids.)

About ids and inheritance:
* Would it be a good idea to specify all object pointers as type ObjectId in
the XML-Model file and tell how this is mapped to the DB in the adaptor?
(integer is enough?)

* May be ObjectIds should be unique throughout the database? (A seperate
procedure would dispatch new objectids, using some high:low algorithm.) See
next point. Also good for replication.

* Either the foreign class (id) has to be stored with each foreign key, or
the object id contains the class id as part of it (MiddleKit does this).

* How would this be treated in queries? Would a query return objects of
several tables? (This may require extra queries. A simple INNER JOIN
wouldn't do it.)

Inheritance makes it real complicated, and in practice, may not be so
important, depending on the object-model design.

More to come,

Erny