Hello Cybrosys,
thank you for your answer, but I was not looking for such filters but to filter the list of items that are available for selection in a dropdown list field in a form. I cannot seem to be able to answer again my own question nor to add any picture in this comment, so I have added a new topic that I hope is explaining much better my problem: https://www.odoo.com/es_ES/forum/ayuda-1/filter-dropdown-items-shown-in-form-224751
Will you be interested in helping me solving my problem, please take a look at my new topic so that you can better understand my problem and hopefuly have a solution for it.
Thank you for your help!

Please find code here :-

@api.onchange('department_id')
def onchange_department_id(self):
if self._context.get('onchange_dept'):
self.team_leader_id = False
if self.department_id:
user_ids = self.env.ref(
'training_management.group_team_lead').users.ids
partner_ids = self.env['res.users'].browse(user_ids).partner_id
if not self.department_id.all_dept:
partner_ids = partner_ids.filtered(
lambda partner: partner.department_id.id == \
self.department_id.id)
return {'domain': {'team_leader_id': [
('id', 'in', partner_ids.ids)]}}
return {'domain': {'team_leader_id': False}}

Dear Jainesh,

thank you very much for your answer, but I have to admit I am not able to understand anything of the code you have attached... Where do I have to insert this code?

Also, I was hoping that this filter I need would be possible to be setup at the frontend, using the "Manage Filters" debug option for the "New Ticket" form.

Is it possible to add the filter I need using Odoo's "Manage Filters" integrated tool? If so, how can I do it?

Thank you!