Rails How to add observer to only one custom method

Question

I would like to create an observer which will observe only one custom method.

I got Baner model. For each call for image method I would like to increase pageview field.

class Baner < ActiveRecord::Base

has_attached_file :image

def pageview_inc
  pageview += 1
  save
end

alias old_image image

def image
  old_image
end
end

Is it possibly to set observer for only one custom method? That after image method call pageview_inc method will be executed.

EDIT

If i change that method for

  def image                                                            
    old_image
    self.pageview   += 1
    self.save!
  end

And I get stack level too deep.

The same effect for

  def image    
    self.pageview   += 1
    self.save!                                                        
    old_image
  end

It tried that. But I get a recursion and I get stack level to deep. — nothing-special-here, Oct 26 '11 at 13:04
Are you using an observer? If so, where is the observer code? — Shreyas, Oct 26 '11 at 13:50

score 1 · Accepted Answer · edited May 23 '17 at 11:55

class Baner < ActiveRecord::Base

  has_attached_file :image

  alias_method :old_image, :image

  def image
    increment!(:pageview)
    old_image
  end
end

Two things here:

1) see this question: Should I use alias or alias_method?

2) increment! will update the counter without saving the entire model, avoiding possible calls to image in the process of saving it (thus causing a recursion loop).

score 0 · Answer 2 · answered Oct 26 '11 at 15:29

0

This should accomplish your goal:

def image
  old_image
  write_attribute("pageview", pageview + 1)
end

answered Oct 26 '11 at 15:29

Ryan

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Rails How to add observer to only one custom method

2 Answers2