def get_lobject(self, mode=None):
"""Return an open file bounded to the represented large
object. This is a context manager, so it should be used with
the `with' clause this way:
with fsobject.get_lobject() as lo:
mode (string): how to open the file (r -> read, w -> write,
b -> binary). If None, use `rb'.
"""
if mode is None:
mode = 'rb'
# Here we rely on the fact that we're using psycopg2 as
# PostgreSQL backend
lo = session.connection().connection.lobject(self.loid, mode)
if self.loid == 0:
self.loid = lo.oid
try:
yield lo
finally:
lo.close()
def check_lobject(self):
"""Check that the referenced large object is actually
available in the database.
"""
try:
lo = session.connection().connection.lobject(self.loid)
lo.close()
return True
except OperationalError:
return False
