How to call active record's association method if we have same method name in current model

Question

Using Ruby and Rails, I did following code

class Department
end
class Employee
  field :depaertment_id, :default => nil
  belongs_to :department, :autosave => false
  def department
    dept = self.super.department # check whether associated department object exists as per self.department active record's method
    if dept.nil?
      #other operation
    end
  end
end

Here from department method I need get department object

If I do following code then department object is easily available as per rails association

class Employee
 field :depaertment_id, :default => nil
 belongs_to :department, :autosave => false
 def get_department
   dept = self.department 
   if dept.nil?
     #other operation
   end
 end
end

How can I get department object?

perhaps add a mongoid tag in there to help you get better scoped answers for what you require? — John Hayes-Reed, Nov 18 '16 at 08:59

John Hayes-Reed · Answer 1 · 2016-11-18T08:34:41.197

1

You could use the association method and then load the target of the association, for example:

def department
    dept = self.association(:department).load_target
    if dept.nil?
        #other operation
    end
end

this will load the related association instead of recursively calling your department method

edited Nov 18 '16 at 08:34

answered Nov 18 '16 at 08:26

John Hayes-Reed

1,358
7
13

*** NoMethodError Exception: undefined method `association' for # – Darshan Patel Nov 18 '16 at 08:38
what version of ruby and what version of rails are you using? – John Hayes-Reed Nov 18 '16 at 08:40
`Rails 3.1.3` and `Ruby 1.9.3p448 (2013-06-27 revision 41675) [x86_64-darwin13.4.0]` – Darshan Patel Nov 18 '16 at 08:42
1

ahh, right, my bad, i just realised your Employee class isnt deriving from ActiveRecord, so the syntax or method may be different – John Hayes-Reed Nov 18 '16 at 08:44
`load_target` worked for me. The problem as that returns an array instead of an ActiveRecord collection, so it can't be chained with a `where` or any other. – Alter Lagos Sep 16 '21 at 03:52

score 0 · Accepted Answer · edited May 23 '17 at 10:30

0

Used Method Wrapping from Monkey patching

class Department
end
class Employee
  field :depaertment_id, :default => nil
  belongs_to :department, :autosave => false
  old_dept = instance_method(:department)
  define_method(:department) do
  dept = old_bar.bind(self).()
  if dept.nil?
      #other code...
  end
end

edited May 23 '17 at 10:30

Community

1
1

answered Nov 21 '16 at 05:00

Darshan Patel

3,176
6
26
49

score 0 · Answer 3 · answered Mar 10 '22 at 11:37

Not tested in console, but in theory, I think super should be enough:

class Employee
  belongs_to :department, :autosave => false

  def department
    # super will load the department association

    if super.nil?
      # Do your override here.
    else
      # to return the default
      super
    end
  end
end

super will try to find #department method in the superclass of the Parent class

More info here: https://medium.com/rubycademy/the-super-keyword-a75b67f46f05

This should also works in has_many association, eg `super.where(condition)` — Christian Angel Galamay, Mar 10 '22 at 11:38

How to call active record's association method if we have same method name in current model

3 Answers3