On Sun, 2011-04-10 at 13:06 +0200, Murray Cumming wrote: > On Sun, 2011-04-10 at 11:52 +0200, Murray Cumming wrote: > > On Sat, 2011-04-09 at 18:39 +0200, Vivien Malerba wrote: > > > On 8 April 2011 22:12, Murray Cumming <[email protected]> wrote: > > > > GObject+Introspection is working quite well for me now with libgda. > > > > Thanks. I am glad that pygda is now obsolete, so it's one less module > > > > for me to maintain. > > > > > > > > However, I'm getting an error when trying to get the values from the > > > > DataModel with get_value_at(). For instance, this script > > > > http://git.gnome.org/browse/pygda/tree/examples/gda/select.py?h=introspection > > > > produces this error: > > > > > > > > Traceback (most recent call last): > > > > File "./select.py", line 61, in <module> > > > > main () > > > > File "./select.py", line 57, in main > > > > print " value=", data_model.get_value_at(col_index, > > > > row_index); > > > > File "/opt/gnome230/lib/python2.7/site-packages/gi/types.py", line 44, > > > > in function > > > > return info.invoke(*args) > > > > TypeError: unknown type (null) > > > > > > > > > > > > Presumably it doesn't like GdaValues with GType=0 (when > > > > gda_value_is_null(gvalue) is true). > > > > > > Yes, the a GValue with a 0 GType represents a SQL NULL value, whereas > > > if the returned value is NULL (the C NULL) then it means there was an > > > error retreiving the value, hence the difference between the 2.
The PyGObject developers don't seem happy with this: https://bugzilla.gnome.org/show_bug.cgi?id=647272#c2 Maybe it's something we can change in libgda-5.0. > > Can we just ignore that meaning of C NULL? We might need to check that > > everything throws a GError instead, but the GdaConnection functions > > already do: > > http://developer.gnome.org/libgda/unstable/GdaConnection.html#gda-connection-execute-select-command > > > > Otherwise we would need to distinguish between a SQL Null value and a C > > NULL value, which would be hard in Python unless we have a Gda.Null > > class with a GDA_TYPE_NULL GType. I don't think it's worth it unless we > > can't always use GError instead. > > We might also want some automatic Python conversion between Gda.Numeric > and python types such as Int. Otherwise we see errors such as this: > TypeError: unsupported operand type(s) for +=: 'Numeric' and 'int'. > > We can instead do > number = datamodel.get_value_at(0,0) > actual_number = float(number.number) > but that probably converts the number based on the current locale, > instead of the C locale used by the GdaNumeric::number string. > -- [email protected] www.murrayc.com www.openismus.com _______________________________________________ gnome-db-list mailing list [email protected] http://mail.gnome.org/mailman/listinfo/gnome-db-list
