# KeyError: 'gnuhealth.model' when i use Many2One field
**URL:** https://discuss.tryton.org/t/keyerror-gnuhealth-model-when-i-use-many2one-field/6065
**Category:** Developer
**Created:** [April 8, 2023, 7:40am UTC](https://discuss.tryton.org/t/keyerror-gnuhealth-model-when-i-use-many2one-field/6065 "2023-04-08T07:40:12Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@danhedaiat](https://discuss.tryton.org/u/danhedaiat)
#### Post date: [April 8, 2023, 7:40am UTC](https://discuss.tryton.org/t/keyerror-gnuhealth-model-when-i-use-many2one-field/6065/1 "2023-04-08T07:40:12Z")
in my module i want to use some relation between the models and my own model, so i do this:
```auto
class NurseCall(ModelSQL, ModelView):
"Nurse Call"
__name__ = "arnika.nurse.call"
name = fields.Many2One('gnuhealth.patient', 'Patient')
date = fields.DateTime('Date')
bed = fields.Many2One("gnuhealth.hospital.bed", 'nurse_call')
health_professional = fields.Many2One('gnuhealth.healthprofessional','Health Professional', readonly=True)
@classmethod
def __setup__ (cls):
super(). __setup__ ()
t = cls. __table__ ()
cls._sql_constraints = [
('name_uniq', Unique(t, t.name), 'The Name must be unique !'),]
```
and when i run trytond-admin -d test -u module its raise this error :
```auto
Traceback (most recent call last):
File "gnuhealth/tryton/server/trytond-6.0.27/bin/trytond-admin", line 23, in
admin.run(options)
File "/home/gnuhealth/gnuhealth/tryton/server/trytond-6.0.27/trytond/admin.py", line 53, in run
pool.init(update=options.update, lang=list(lang),
File "/home/gnuhealth/gnuhealth/tryton/server/trytond-6.0.27/trytond/pool.py", line 164, in init
restart = not load_modules(
File "/home/gnuhealth/gnuhealth/tryton/server/trytond-6.0.27/trytond/modules/ __init__.py", line 438, in load_modules
_load_modules(update)
File "/home/gnuhealth/gnuhealth/tryton/server/trytond-6.0.27/trytond/modules/ __init__.py", line 406, in _load_modules
load_module_graph(graph, pool, update, lang)
File "/home/gnuhealth/gnuhealth/tryton/server/trytond-6.0.27/trytond/modules/ __init__.py", line 238, in load_module_graph
cls. __register__ (module)
File "/home/gnuhealth/gnuhealth/tryton/server/trytond-6.0.27/trytond/model/modelsql.py", line 264, in __register__
ref_model = pool.get(field.model_name)
File "/home/gnuhealth/gnuhealth/tryton/server/trytond-6.0.27/trytond/pool.py", line 187, in get
return self._pool[self.database_name][type][name]
KeyError: 'gnuhealth.hospital.bed'
```
and if I comment the `#bed = fields.Many2One("gnuhealth.hospital.bed", 'nurse_call')` line, i still get this error but for one of other field and all of module are activated
---
### Author:  [@ced](https://discuss.tryton.org/u/ced)
#### Post date: [April 8, 2023, 9:38am UTC](https://discuss.tryton.org/t/keyerror-gnuhealth-model-when-i-use-many2one-field/6065/2 "2023-04-08T09:38:31Z")
This sounds like you have dependency declaration issue. If your module is using model declared in other modules, you must declare the other module as a dependency. So it is loaded before yours and the models will be in the pool when needed.
---
### Author:  [@danhedaiat](https://discuss.tryton.org/u/danhedaiat)
#### Post date: [April 8, 2023, 10:13am UTC](https://discuss.tryton.org/t/keyerror-gnuhealth-model-when-i-use-many2one-field/6065/4 "2023-04-08T10:13:19Z")
its worked, thank you 🥹
---
### Author:  [@system](https://discuss.tryton.org/u/system)
#### Post date: [May 8, 2023, 10:14am UTC](https://discuss.tryton.org/t/keyerror-gnuhealth-model-when-i-use-many2one-field/6065/5 "2023-05-08T10:14:17Z")
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