Michael Bayer wrote: > ........However i might suggest that this whole thread, "controlling return > types", perhaps be expanded to include "controlling *input* types and > return types"........
The pysqlite register_adapter and register_converter do this (in that order). I've not used it in anger but I like the simplicity of the API, see http://initd.org/pub/software/pysqlite/doc/usage-guide.html#converting-sqlite-values-to-custom-python-types for an example. pysqlite approach does have implications for the SQL that is then used but that isn't relevant to other databases so the api/approach could be appropriated :-) I'm not familiar with psycopg's approach to be able to compare with pysqlite without research. The big question is when should mapping take place? On the connection level, statement level, or column level. E.g. mapping varchar to a python varchar type that contains length and data connection level - all varchars in DBMS get returned get returned as varchar python type statement level - all varchars in specific .execute() get returned as varchar python type column level - only specific varchars in specific .execute() get returned as varchar python type, i.e. some varchars could come back as regular python strings The pysqlite approach is to use strings as type identifiers for the converter, I get the impression Art is not in favor if this approach but the dbms type param is likely to be DBMS specific so whether it is a string, a tuple of major/minor, etc. may not matter. If the driver offers constants for basic types that would be fine. Here is an example following the pysqlite approach, using connection level mapping. It is usually easy to discuss what is good/bad about an idea if there is an example to critic: import mydbapi # Register the python2db adapter mydbapi.register_adapter(mydbapi.varcharClass, mydbapi.adapt_varchar) # Register the db2python converter mydbapi.register_converter(mydbapi.varcharType, mydbapi.convert_varchar) con = mydbapi.connect(".......", use_type_mapping=TRUE) cur = con.cursor() cur.execute("select myvarchar from mytable") cur.fetch()[0] ## type would be Python type "mydbapi.varcharClass" Chris _______________________________________________ DB-SIG maillist - DB-SIG@python.org http://mail.python.org/mailman/listinfo/db-sig
