CODEWITHSUNDEEP
ruby-on-railsruby
Noam B.
Noam B.

Reputation: 3250

how to initialize an attribute of object

I have a Metric class:

class Metric < ApplicationController

  attr_accessor :capability, :behavior

  def initialize(family_id)
    @capability = 5
  end 
end

In a controller I do:

metrics = Metric.new(222)

Then I try to get the capability attribute with:

puts metrics.capability

but I get an error: 

NoMethodError Exception: private method `capability' called for #<Metric:0xa7bb4b0 @capability=5>

What am I doing wrong???

Upvotes: 1

Views: 47

Answers (1)

Paritosh Piplewar
Paritosh Piplewar

Reputation: 8132

You dont need to inherit from ApplicationController. Stop inheriting it, it will start working.

If you want to initialise the attribute in all actions, all you have to do is this 

class Metric 

  attr_accessor :capability, :behavior

  def initialize(family_id)
    @capability = 5
  end 
end


 class ApplicationController < ActionController::Base
  before_action :initialize_metric_attribute

   def initialize_metric_attribute
     @capability = Metric.new(10)
   end
 end

Edit based on comment: You are inheriting from ApplicationController. It should only be inherited only when you want to write some action. For writing custom classes,you dont need to do anything. If required you can inherit ActiveRecord::Base.

Since, you are have initialize method in your class metric class, you dont even need AR.

Why it worked ?

We have just used before_filter callback which initialize your attribute. its Simple Ruby and Rails concept.

Upvotes: 1

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