[web2py] update=request.now not working

[JimK]

I have the following table:

Model
db.define_table('queries',
                                Field('my_db', 'string', required=True),
                                Field('title', 'text', required=True),
                                Field('query', 'text', required=True),
                                Field('modified_by', 'string', required=True, 
writable=False,
readable=True),
                                Field('modified_date', 'datetime', 
update=request.now,
writable=False, readable=True),
                                Field('creation_date', 'datetime', 
default=request.now,
writable=False, readable=True),
                                Field('enabled', 'boolean', default=True),
                                Field('dependence', 'integer', default=1),
                                Field('info_needed', 'string', default=None),
                                migrate=True)

Controller
def edit_query:
    record = db.queries(db.queries.id==query_id)
    form=SQLFORM(db.queries, record)
    if form.accepts(request.vars, session):
            redirect(URL('default','queries'))
            response.flash = 'query updated'
    elif form.errors:
    response.flash = 'form has errors'
    return dict(form=form)

When I edit an existing queries row, modified_date does not get
updated with the current datetime.datetime.now (or anything for that
matter).  Any ideas?


Jim