[Zope] Newbie question--external methods, DTML and DB connection persistence

[Andy Dustman]

On 30 Aug 2001 00:13:01 -0400, elian@inbrief.net wrote:

> 1. Whether it is possible for external methods to send SQL queries to an
> RDBMS using database connections defined in Zope, so that the persistent
> database connections are used. Or, if this is not possible, how to do so
> with Python scripts.

If you can acquire the DA, you can call it to get the underlying DB, and
then use DB.query(query_string), but I do not believe this will cache
your queries. You are probably better off defining your queries in ZSQL
Methods and calling those from Python Script. It may be possible to call
them from an External Method.
 
> 2. How to return result rows from a SQL selection in an external method or
> Python script so that <dtml-in  my_external_method> and <dtml-var
> column_name_from_result_set> tags work as well as when using ZSQL methods.

The query() method above returns two items: a sequence of dictionaries,
each dictionary describing a column; and a sequence (rows) of sequences
(column) for the result set. You'll probably have to dig into a DA (like
ZMySQLDA) to see what is going on. However, the DA (see
Shared.DC.ZRDB.DA.__call__ for more details) also does caching and
Brains, and mangles the result a bit (Shared.DC.ZRDB.Results.Results).

In short, while doing the above is an interesting exercise for the
reader, you should try to use a Z SQL Method rather than trying to
interact directly with a database connection. You could also create your
own (Python, not Zope) database connection in an External Method or
Product (I believe MysqlUserFolder does this). However, I'm not sure how
you would acquire the Z SQL Method in the first place. You'd have to
pass it to your External Method, or pass the current object and get the
Z SQL Method by acquisition.

In other words, yes, it's probably possible.

-- 
Andy Dustman         PGP: 0x930B8AB6
    @       .net     http://dustman.net/andy
I'll give spammers one bite of the apple, but they'll
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