Getting TODs from Depth 1 maps

As we discussed in the last TRP dev call. I tried to get the TODs of an existing depth 1 map. I see two different behaviors. The first is when the map select is together with the tods line:

In [1]: from mapcat.helper import settings
   ...: from mapcat.database import DepthOneMapTable, TODDepthOneTable
   ...: map_name = "17569/depth1_1756951955_i1_f090"
   ...: with settings.session() as session:
   ...:     existing_map = session.query(DepthOneMapTable).filter_by(map_name=map_name).first()
   ...:     map_tods = existing_map.tods
   ...:

In [2]: map_tods
Out[2]:
[TODDepthOneTable(ctime=1756951955.5577126, frequency='f090', el_throw=0.0009, start_time=1756951955.5577126, scan_type='obs', roll_center=60.0, stop_time=1756954380.7577126, subtype='cmb', roll_throw=0.0015, nsamples=485041, wafer_count=3, wafer_slots_list='ws0,ws1,ws2', telescope='lat', duration=2425.2000000476837, stream_ids_list='ufm_mv21,ufm_mv24,ufm_mv28', obs_id='obs_1756951929_lati1_111', telescope_flavor='lat', az_center=250.8445, tod_id=5, tube_slot='i1', az_throw=12.0033, pwv=None, tube_flavor='mf', el_center=140.0002),
 TODDepthOneTable(ctime=1756954562.2477126, frequency='f090', el_throw=0.001, start_time=1756954562.2477126, scan_type='obs', roll_center=60.0003, stop_time=1756957110.4527125, subtype='cmb', roll_throw=0.0016, nsamples=509642, wafer_count=3, wafer_slots_list='ws0,ws1,ws2', telescope='lat', duration=2548.204999923706, stream_ids_list='ufm_mv21,ufm_mv24,ufm_mv28', obs_id='obs_1756954534_lati1_111', telescope_flavor='lat', az_center=250.8447, tod_id=6, tube_slot='i1', az_throw=12.0028, pwv=None, tube_flavor='mf', el_center=140.0002),
 TODDepthOneTable(ctime=1756957278.9727125, frequency='f090', el_throw=0.0009, start_time=1756957278.9727125, scan_type='obs', roll_center=60.0002, stop_time=1756959840.1677125, subtype='cmb', roll_throw=0.0015, nsamples=512240, wafer_count=3, wafer_slots_list='ws0,ws1,ws2', telescope='lat', duration=2561.194999933243, stream_ids_list='ufm_mv21,ufm_mv24,ufm_mv28', obs_id='obs_1756957257_lati1_111', telescope_flavor='lat', az_center=250.8445, tod_id=7, tube_slot='i1', az_throw=12.0027, pwv=None, tube_flavor='mf', el_center=140.0002),
 TODDepthOneTable(ctime=1756960007.7327125, frequency='f090', el_throw=0.0009, start_time=1756960007.7327125, scan_type='obs', roll_center=60.0003, stop_time=1756963440.7577126, subtype='cmb', roll_throw=0.0015, nsamples=686606, wafer_count=3, wafer_slots_list='ws0,ws1,ws2', telescope='lat', duration=3433.0250000953674, stream_ids_list='ufm_mv21,ufm_mv24,ufm_mv28', obs_id='obs_1756959981_lati1_111', telescope_flavor='lat', az_center=250.8447, tod_id=8, tube_slot='i1', az_throw=12.0025, pwv=None, tube_flavor='mf', el_center=140.0001)]

whereas:

In [1]: from mapcat.helper import settings
   ...: from mapcat.database import DepthOneMapTable, TODDepthOneTable
   ...: map_name = "17569/depth1_1756951955_i1_f090"
   ...: with settings.session() as session:
   ...:     existing_map = session.query(DepthOneMapTable).filter_by(map_name=map_name).first()
   ...: with settings.session() as session:
   ...:     map_tods = existing_map.tods
   ...:
---------------------------------------------------------------------------
DetachedInstanceError                     Traceback (most recent call last)
Cell In[1], line 7
      5     existing_map = session.query(DepthOneMapTable).filter_by(map_name=map_name).first()
      6 with settings.session() as session:
----> 7     map_tods = existing_map.tods

File /scratch/gpfs/SIMONSOBS/env/dev/soconda_dev/lib/python3.12/site-packages/sqlalchemy/orm/attributes.py:569, in InstrumentedAttribute.__get__(self, instance, owner)
    567 except AttributeError as err:
    568     raise orm_exc.UnmappedInstanceError(instance) from err
--> 569 return self.impl.get(state, dict_)

File /scratch/gpfs/SIMONSOBS/env/dev/soconda_dev/lib/python3.12/site-packages/sqlalchemy/orm/attributes.py:1096, in AttributeImpl.get(self, state, dict_, passive)
   1093 if not passive & CALLABLES_OK:
   1094     return PASSIVE_NO_RESULT
-> 1096 value = self._fire_loader_callables(state, key, passive)
   1098 if value is PASSIVE_NO_RESULT or value is NO_VALUE:
   1099     return value

File /scratch/gpfs/SIMONSOBS/env/dev/soconda_dev/lib/python3.12/site-packages/sqlalchemy/orm/attributes.py:1131, in AttributeImpl._fire_loader_callables(self, state, key, passive)
   1129     return callable_(state, passive)
   1130 elif self.callable_:
-> 1131     return self.callable_(state, passive)
   1132 else:
   1133     return ATTR_EMPTY

File /scratch/gpfs/SIMONSOBS/env/dev/soconda_dev/lib/python3.12/site-packages/sqlalchemy/orm/strategies.py:922, in LazyLoader._load_for_state(self, state, passive, loadopt, extra_criteria, extra_options, alternate_effective_path, execution_options)
    919     if passive & PassiveFlag.NO_RAISE:
    920         return LoaderCallableStatus.PASSIVE_NO_RESULT
--> 922     raise orm_exc.DetachedInstanceError(
    923         "Parent instance %s is not bound to a Session; "
    924         "lazy load operation of attribute '%s' cannot proceed"
    925         % (orm_util.state_str(state), self.key)
    926     )
    928 # if we have a simple primary key load, check the
    929 # identity map without generating a Query at all
    930 if use_get:

DetachedInstanceError: Parent instance <DepthOneMapTable at 0x14cad8fb4e10> is not bound to a Session; lazy load operation of attribute 'tods' cannot proceed (Background on this error at: https://sqlalche.me/e/20/bhk3)

I think it should be the same behavior. If you want it to be lazy under the session, can we have a way to get all the information from the DB?

Reproduce the two session lifecycles using settings.session(), DepthOneMapTable, and its tods relationship from mapcat.database. Inspect how the relationship is loaded after the session closes and determine the expected way to access the TOD data. Done means the two access patterns behave consistently or a clear database-backed access method is provided.