There are two models: Companies and Employees table companies integer :ceo_id integer :cfo_id end table employees string :name end How should I implement <company instance>.ceo and <company instance>.cfo which will return the CEO's and CFO's employee records? Should I do:
There are two models: Companies and Employees
table companies
integer :ceo_id
integer :cfo_id
end
table employees
string :name
end
How should I implement .ceo and .cfo
which will return the CEO’s and CFO’s employee records?
Should I do:
(1)
class Company
belongs_to :ceo, :class_name => ‘Employee’
belongs_to :cfo, :class_name => ‘Employee’
end
or
(2)
class Company
has_one :ceo, :class_name => ‘Employee’, :primary_key => :ceo_id,
:foreign_key => :id
has_one :cfo, :class_name => ‘Employee’, :primary_key => :cfo_id,
:foreign_key => :id
end
(1) is definitely simpler, but I don’t quite get over the psychological
hurdle why Company should ‘belongs_to’ a ceo employee, but not ‘has_one’
ceo. Am I missing something?
You might have a good reason, but what about just add a :title attribute to Employees. Then you just ask for Company.include(“employees”).where(“employee.title=‘ceo’”)? (my query might not be exact but you get the idea…)
Worst case you can add logic to your models to validate to only allow one ceo / cfo per company.
Just a thought.
yeah…David is right. Just add a boolean field for each of the attributes i.e ceo and cfo in the employees because if you look at the picture in real world, an employee could be either an ceo, an cfo or just an employee.
There are two models: Companies and Employees table companies integer :ceo_id integer :cfo_id end table employees string :name end How should I implement <company instance>.ceo and <company instance>.cfo which will return the CEO's and CFO's employee records? Should I do: ------ (1) class Company belongs_to :ceo, :class_name => 'Employee' belongs_to :cfo, :class_name => 'Employee' end or (2) class Company has_one :ceo, :class_name => 'Employee', :primary_key => :ceo_id, :foreign_key => :id has_one :cfo, :class_name => 'Employee', :primary_key => :cfo_id, :foreign_key => :id end
The second one will not work with the db schema you have shown, the id fields would have to be in the Employee.
I would suggest maybe company has_many employees and employee belongs_to company and then use roles to specify their function. Google for Rails Roles and you will find many examples on how to do this. The simplest is just a role field in the employee record, but if you want an employee to be able to fill multiple roles then you probably need a Roles table.
----- (1) is definitely simpler, but I don't quite get over the psychological hurdle why Company should 'belongs_to' a ceo employee, but not 'has_one' ceo. Am I missing something?
No, you are not missing anything, sometimes the words just do not seem to match the real world.
Colin
David Kahn-3 wrote: