Module is not JSON serializable

Hello ,

i just implemented a one2many relationship

class HealthInstitutionHealthProf(ModelSQL, ModelView):

    'Health Institution Health Prof'

    __name__ = 'gnuhealth.institution.healthprof'

    name = fields.Many2One('gnuhealth.institution', 'Institution',


    healthprof = fields.Many2One('gnuhealth.healthprofessional', 'Health Professional',



    def get_rec_name(self, name):

        if self.healthprof :

            return self.healthprof .name
class HealthInstitutionO2M(ModelSQL, ModelView):

    'Health Institution'

    __name__ = 'gnuhealth.institution'

    healthprof = fields.One2Many('gnuhealth.institution.healthprof',

        'name','Health Prof',

        help="Operational Sectors covered by this institution")

but i am getting the following error

Traceback (most recent call last):
  File "/home/gnuhealth/.local/lib/python3.8/site-packages/werkzeug/", line 306, in run_wsgi
  File "/home/gnuhealth/.local/lib/python3.8/site-packages/werkzeug/", line 294, in execute
    application_iter = app(environ, start_response)
  File "/home/gnuhealth/gnuhealth/tryton/server/trytond-5.0.28/trytond/", line 121, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/gnuhealth/gnuhealth/tryton/server/trytond-5.0.28/trytond/", line 127, in __call__
    return, start_response)
  File "/home/gnuhealth/gnuhealth/tryton/server/trytond-5.0.28/trytond/", line 108, in wsgi_app
    response = cls.response(data, request)
  File "/home/gnuhealth/gnuhealth/tryton/server/trytond-5.0.28/trytond/protocols/", line 159, in response
    return Response(json.dumps(
  File "/usr/lib/python3.8/json/", line 234, in dumps
    return cls(
  File "/usr/lib/python3.8/json/", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib/python3.8/json/", line 257, in iterencode
    return _iterencode(o, 0)
  File "/home/gnuhealth/gnuhealth/tryton/server/trytond-5.0.28/trytond/protocols/", line 61, in default
    return marshaller(obj)
  File "/usr/lib/python3.8/json/", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type is not JSON serializable

any idea where it did go wrong ?

In get_rec_name you return the attribute name as value but it is a Many2One so it is an instance instead of a string.
I advise to not use name to name Many2One because it is confusing. Here it will be better named institution.

Thanks a lot @ced
that totally solved my issue

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