CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3
AnApprentice
AnApprentice

Reputation: 110980

Rails 3 Observer -- looking to learn how to implement an Observer for multiple models

I have the following Observer:

class NewsFeedObserver < ActiveRecord::Observer
  observe :photo, :comment

  def after_create(record)
  end
end

What'd I'd like to learn how to do is add a SWITCH/IF statement in the after_create, so I know which model was created

Something like:

after_create(record)
switch model_type
case "photo"
 do some stuff
case "comment"
 do some other stuff
end

Or easier to visualize:

if record == 'Photo'

How can I take record, and determine the model name?

Upvotes: 1

Views: 1763

Answers (2)

maček
maček

Reputation: 77778

In a comment, I notice you found this works using record.class.name but that's not very idiomatic Ruby. The Ruby case statement uses === for comparison which will work perfectly for you if you implement it properly.

class NewsFeedObserver < ActiveRecord::Observer
  observe :photo, :comment

  def after_create(record)
    case record
      when Photo
        # do photo stuff
      when Comment
        # do comment stuff
      else
        # do default stuff
    end
  end
end

This essentially converts to:

if Photo === record
  # do photo stuff
elsif Comment === record
  # do comment stuff
else
  # do default stuff
end

I advise you to note the following:

class Sample
end

s = Sample.new

Foo === s   # true   uses Class#===
s === Foo   # false  uses Object#===

=== is implemented differently in Class and Object

Upvotes: 3

Rishav Rastogi
Rishav Rastogi

Reputation: 15492

You need to setup separate observers for separate models

So for User => UserObserver , Photo => PhotoObserver

You need to tell the rails app what observers to use, that you specify in config/environment.rb

Atleast this is the standard way. For more details

http://guides.rubyonrails.org/active_record_validations_callbacks.html#observers

Upvotes: 1

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