TypeError: cannot pickle 'IntVar' object

[Alberto Manzini]

Hi everyone, I was trying to pickle a model but this error was raised

TypeError: cannot pickle 'IntVar' object

Could it be an issue with protobuf version?

Here is my pip freeze

numpy==1.26.0
ortools==9.12.4544
pandas==2.2.0
protobuf==5.29.4

I tried both on python=3.8.10 and 3.12.9

Here is the toy model I'm using

from ortools.sat.python import cp_model

import pickle

model = cp_model.CpModel()

list_presences = []
list_intervals = []
for i in range(11):
  start = model.NewIntVar(0, 10, name=f'start_{i}')
  end = model.NewIntVar(0, 10, name=f'end_{i}')
  duration = model.NewIntVar(1, 2, name=f'duration_{i}')
  presence = model.NewBoolVar(name=f'presence_{i}')
  interval = model.NewOptionalIntervalVar(start, duration, end, presence, name=f'interval_{i}')
  list_presences.append(presence)
  list_intervals.append(interval)

model.AddNoOverlap(list_intervals)
model.Add(sum(list_presences) == len(list_presences)).OnlyEnforceIf(presence.Not())

with open(r'test.pkl', 'wb') as f:
  pickle.dump(model, f)

[Laurent Perron]

Fixed on main. 

--Laurent

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[Alberto Manzini]

Wow, thanks

Can I pip install it with some command or should I clone the repo, build the library and get the wheel for main branch?

[Laurent Perron]

you need to build. 

Use the v99bugfix branch

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

To view this discussion visit https://groups.google.com/d/msgid/or-tools-discuss/915a0074-7c5b-4f49-b423-9e5a629f6344n%40googlegroups.com.

[Alberto Manzini]

Ok got it, thanks

[Zhiwei Feng]

Hi Laurent,

I still have the same error:TypeError: cannot pickle 'IntVar' object on new version: Name: ortools Version: 9.14.6206.
we can easily reproduce the error with above toy model

[Laurent Perron]

pretty sure this is fixed on 9.15

Laurent Perron | Operations Research | lpe...@google.com | (33) 1 42 68 53 00

To view this discussion visit https://groups.google.com/d/msgid/or-tools-discuss/01798c77-1f47-46a3-b517-296972648f07n%40googlegroups.com.

[Zhiwei Feng]

with 9.15.6755, i still got error:
Traceback (most recent call last):
  File "/Users/User/Documents/Git/Engine/pyxis-algorithm/test/test_pickle.py", line 21, in <module>
    pickle.dump(model, f)
    ~~~~~~~~~~~^^^^^^^^^^
TypeError: cannot pickle 'CpModel' object

test_pickle.py is exactly the above test code

[Laurent Perron]

I have added support for copy/deepcopy, not pickle

To view this discussion visit https://groups.google.com/d/msgid/or-tools-discuss/923aceec-9190-4809-8bf1-898e3ed1d3edn%40googlegroups.com.

--

--Laurent