Reservations.to_json() fails with "TypeError: Object of type ReservationFlags is not JSON serializable"

[behnle]

We have the following reservation on our cluster:

[root@slurm-web restapi]# scontrol show res
ReservationName=comsol StartTime=2026-06-10T17:00:01 EndTime=2027-06-10T17:00:01 Duration=365-00:00:00
   Nodes=(null) NodeCnt=0 CoreCnt=0 Features=(null) PartitionName=compute Flags=ANY_NODES
   TRES=(null)
   AllowedPartitions=(null) QOS=(null)
   Users=(null) Groups=(null) Accounts=computeusers Licenses=COMSOLUSER:1 State=ACTIVE BurstBuffer=(null)
   MaxStartDelay=(null)

I can load the reservation, i can also convert it to a dictionary (notably, recursive=False and recursice=True behave identically):

>>> pprint.pp(pyslurm.Reservations().load().to_dict())
{'comsol': {'accounts': ['computeusers'],
            'burst_buffer': None,
            'cluster': 'cluster',
            'comment': None,
            'cpu_ids_by_node': {},
            'cpus': 0,
            'duration': 525600,
            'end_time': 1812639601,
            'features': [],
            'flags': <ReservationFlags.ANY_NODES: 256>,
            'groups': [],
            'is_active': True,
            'licenses': ['COMSOLUSER:1'],
            'max_start_delay': None,
            'name': 'comsol',
            'node_count': 0,
            'nodes': None,
            'partition': 'compute',
            'purge_time': 300,
            'reoccurrence': <ReservationReoccurrence.NO: 'NO'>,
            'start_time': 1781103601,
            'tres': {},
            'users': []}}
>>> pprint.pp(pyslurm.Reservations().load().to_dict(recursive=True))
{'comsol': {'accounts': ['computeusers'],
            'burst_buffer': None,
            'cluster': 'cluster',
            'comment': None,
            'cpu_ids_by_node': {},
            'cpus': 0,
            'duration': 525600,
            'end_time': 1812639601,
            'features': [],
            'flags': <ReservationFlags.ANY_NODES: 256>,
            'groups': [],
            'is_active': True,
            'licenses': ['COMSOLUSER:1'],
            'max_start_delay': None,
            'name': 'comsol',
            'node_count': 0,
            'nodes': None,
            'partition': 'compute',
            'purge_time': 300,
            'reoccurrence': <ReservationReoccurrence.NO: 'NO'>,
            'start_time': 1781103601,
            'tres': {},
            'users': []}}

but calling to_json() fails with the following error:

>>> pyslurm.Reservations().load().to_json()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "pyslurm/xcollections.pyx", line 454, in pyslurm.xcollections.MultiClusterMap.to_json
  File "/usr/lib64/python3.9/json/__init__.py", line 231, in dumps
    return _default_encoder.encode(obj)
  File "/usr/lib64/python3.9/json/encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib64/python3.9/json/encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
  File "/usr/lib64/python3.9/json/encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type ReservationFlags is not JSON serializable

This is probably not the intended behaviour. My suspicion is that there is code missing for the serialization of the ReservationFlags and ReservationReoccurrence objects.

Pyslurm version 25.11.2 under python3.9
SLURM 25.11.3

[giovtorres]

@behnle Would you be able to test and confirm a build of the fix-resv branch used for PR #425 works for you?

[behnle]

@giovtorres Sure. Indeed #425 seems to fix the problem.
I cloned the repo, checked out the fix-resv branch, did a pip3.9 install . and tried again.
New behaviour:

[root@slurm-web ~]# python3.9
Python 3.9.25 (main, Dec 18 2025, 08:36:10) 
[GCC 8.5.0 20210514 (Red Hat 8.5.0-28)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pyslurm
>>> import pprint
>>> pprint.pp(pyslurm.Reservations().load().to_dict())
{'comsol': {'accounts': ['lisaplus'],
            'burst_buffer': None,
            'cluster': 'cluster',
            'comment': None,
            'cpu_ids_by_node': {},
            'cpus': 0,
            'duration': 525600,
            'end_time': 1812639601,
            'features': [],
            'flags': ,
            'groups': [],
            'is_active': True,
            'licenses': ['COMSOLUSER:1'],
            'max_start_delay': None,
            'name': 'comsol',
            'node_count': 0,
            'nodes': None,
            'partition': 'lisaplus',
            'purge_time': 300,
            'reoccurrence': ,
            'start_time': 1781103601,
            'tres': {},
            'users': []}}
>>> pprint.pp(pyslurm.Reservations().load().to_dict(recursive=True))
{'comsol': {'accounts': ['lisaplus'],
            'burst_buffer': None,
            'cluster': 'cluster',
            'comment': None,
            'cpu_ids_by_node': {},
            'cpus': 0,
            'duration': 525600,
            'end_time': 1812639601,
            'features': [],
            'flags': ['ANY_NODES'],
            'groups': [],
            'is_active': True,
            'licenses': ['COMSOLUSER:1'],
            'max_start_delay': None,
            'name': 'comsol',
            'node_count': 0,
            'nodes': None,
            'partition': 'lisaplus',
            'purge_time': 300,
            'reoccurrence': 'NO',
            'start_time': 1781103601,
            'tres': {},
            'users': []}}
>>> pyslurm.Reservations().load().to_json()
'{"comsol": {"accounts": ["lisaplus"], "burst_buffer": null, "cluster": "cluster", "comment": null, "cpu_ids_by_node": {}, "cpus": 0, "duration": 525600, "end_time": 1812639601, "features": [], "flags": ["ANY_NODES"], "groups": [], "is_active": true, "licenses": ["COMSOLUSER:1"], "max_start_delay": null, "name": "comsol", "node_count": 0, "nodes": null, "partition": "lisaplus", "purge_time": 300, "reoccurrence": "NO", "start_time": 1781103601, "tres": {}, "users": []}}'

So at least for this simple case where flags and reoccurrence boil down to a single entries, the patch solves the issue 👍 .

From my side, this looks good!