print(self._origin.promotion_id.id)

print value 

odoo.models.NewId object at 0x7f21fb068ac8

for test in self._origin.promotion_id: 

 print(test.id)

print value 

odoo.models.NewId object at 0x7f21fb068ac8

print(self._origin.promotion_id.name)

print value 

TEST it giving perfect result 

other then ID other column i can easily access but in this time i need ID