Serialize SQLAlchemy output to a JSON including column names - json

Question

I've decided to migrate my Django project to work with SqlAlchemy instead of Django ORM and I'm trying to serialize my SqlAlchemy output to a JSON which contains column names.
In Django I had the following code:
logs = Log.objects.values('log_timestamp', 'message', 'exception', 'level__level', 'job_info__job_name', 'machine', 'user', 'job_report__id').filter(job_info__app_id = app_id).order_by('-time_added')[:1]
logs = json.dumps(list(logs), default=views_utils.default_json_serializer)
print(logs)
and here an output example (contains column names):
[{"user": "user", "level__level": "INFO", "message": "this is a message", "log_timestamp": null, "job_info__job_name": "MongoDB_Maintenance", "exception": "exception details", "machine": "machine", "job_report__id": 65}]
Here is my SqlAlchemy code:
res = session.query(func.DATETIME(LogObj.time_added), LogObj.message, LogObj.exception, LogLevelObj.level, LogObj.machine, LogObj.user).\
join(PeriodicJobInfoObj, LogLevelObj, LogObj,aliased=True).\
filter(PeriodicJobInfoObj.app_id == app_id).\
order_by(desc(LogObj.time_added))[:1]
res = json.dumps(res, default=views_utils.default_json_serializer)
print(res)
The output does not contain column names:
[["2015-09-28 15:36:33", "this is a message", "exception details", "CRITICAL", "machine", "user"]]
default_json_serializer code:
def default_json_serializer(obj):
"""Default JSON serializer."""
import calendar, datetime
if isinstance(obj, datetime.datetime):
if obj.utcoffset() is not None:
obj = obj - obj.utcoffset()
millis = int(
calendar.timegm(obj.timetuple()) * 1000 +
obj.microsecond / 1000
)
return millis
How can I achieve similar output like Django does?
(working with Python 3.4.2)

Answer 1

I have managed to do it this way:
def alchemyencoder(obj):
if isinstance(obj, datetime.date):
return obj.isoformat()
elif isinstance(obj, decimal.Decimal):
return float(obj)
I use the above encoder when retrieving records in following way:
row = conn.execute(Model.__table__.select())
d = json.dumps([dict(r) for r in row], default=alchemyencoder)
d = json.JSONDecoder().decode(d)
print(d)