Am 07.11.2007, 21:11 Uhr, schrieb Ken Winter [EMAIL PROTECTED]:
Charlie, thanks for the encouraging response!
Encouraging? Not sure if that's quite the right word! ;-)
Just assuming you did have connections per user, how would you go about
this?
What you suggest (below) is definitely the way I'd like to do this.
However, ZPsycopgDA and its communications with PostgreSQL are currently
black boxes for me, so I think I need some help taking the next steps.
A few hours of poking around have led me to the following fragmentary
ideas.
* I have found what may be a likely candidate for the code that could be
customized: the method DB.query(self, query_string, max_rows=None,
query_data=None) defined (on my Windows system) in C:\Program Files\Plone
2\Data\Products\ZPsycopgDA\db.py.
Yep, that's the place.
* One idea is to parse the query_string in DB.query and, if it contains
an
INSERT or UPDATE command, splice a clause to record the current user's id
into it (e.g. put last_updated_by = request.AUTHENTICATED_USER into the
SET clause of an UPDATE). Doing it this way should require nothing
special
on the PostgreSQL side, since the user identifier would come through as
part
of the INSERT or UPDATE statement.
This is going to be your quickest way assuming you can write a good enough
parser so you don't catch statements with INSERT or UPDATE as part of
the parameters! Using the underlying .execute(SQLStatement, (paras,))
method on the cursor might be preferable and would be available from our
mxODBC Zope DA but this is unfortunately not compatible with ZSQL methods
which predate the Python DB-API. You might, however, be able to use a
stored procedure on the database to execute the query as rendered by the
ZSQL method with the user passed as a parameter to the stored procedure.
Again the mxODBC Zope DA would give you access to the .callproc(). No idea
whether you could write such a stored procedure but I don't see why not.
* The idea of extending the DA pass the current ZOPE user seems
cleaner.
However, I don't know how to get the DA to pass an additional parameter,
and
I don't know how to get PostgreSQL to pick up the parameter so it can
store
it as required. In other words, I don't understand this API, and I don't
know where it is documented.
Zope doesn't support it and unfortunately relational databases aren't
getting the attention they deserve in the Zope world at the moment.
Charlie
--
Charlie Clark
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