> -----Original Message----- > From: sqlalchemy@googlegroups.com > [mailto:sqlalch...@googlegroups.com] On Behalf Of Michael Hipp > Sent: 19 August 2010 23:39 > To: sqlalchemy@googlegroups.com > Subject: Re: [sqlalchemy] Which columns changing during orm commit? > > On 8/19/2010 5:24 AM, Chris Withers wrote: > > Michael Hipp wrote: > >> SQLAlchemy seems pretty smart about updating only the > changed columns > >> in an orm object... > >> > >> If I have an orm object. Something changes one of the columns. Just > >> before I commit() the session, is there a way to tell which columns > >> will be updated vs those that are unchanged? > >> > >> Any way to ascertain the before/after values on those > changed columns? > > > > Here's the basics: > > > > http://www.sqlalchemy.org/docs/session.html#session-attributes > > > > These examples should fill in the rest: > > > > http://www.sqlalchemy.org/trac/wiki/UsageRecipes/VersionedMap > > http://www.sqlalchemy.org/trac/wiki/UsageRecipes/VersionedRows > > http://www.sqlalchemy.org/docs/examples.html?#module-versioning > > Thanks. But I believe all those items deal with which orm > objects (rows) are > changed. I'm asking about columns within an orm object that > might be changed. > > Did I miss something? > > Thanks, > Michael >
You could use mapper.iterate_properties [1] to loop over all the properties of your object, and for each one call attributes.get_history [2] to find out if it has changed. I'm not sure if it's the best way, but it should work. The return value from get_history isn't documented, but the source is pretty simple. If you only want to know if the attribute has changed, you can call the 'has_changes' method. You can look at the 'added' and 'deleted' properties to get the before and after values. Hope that helps, Simon [1] http://www.sqlalchemy.org/docs/reference/orm/mapping.html#sqlalchemy.orm .mapper.Mapper.iterate_properties [2] http://www.sqlalchemy.org/docs/reference/orm/mapping.html#attribute-util ities -- You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalch...@googlegroups.com. To unsubscribe from this group, send email to sqlalchemy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en.
