attr_accessor and attr_reader not working in Rails 4

Question

I am trying to migrate an application to rails 4 and ruby2.

In my model Product, I had this :

attr_accessor :name, :age, :price

which I switched to :

attr_reader :name, :age, :price

In my view I have this :

  %td.small
    = number_with_precision(@p.get_last_usd_price.to_f, precision: 2, delimiter: ",", strip_insignificant_zeros: true)

Everything worked fine with rails 3.2 and attr_accessor. But now I have an issue in get_last_usd_price :

  def get_last_usd_price
    price = 0.0
    puts "--------------------"
    puts self.inspect          #---> prints a #<product> with all the correct attributes
    puts
    puts self.name.inspect     #---> prints nil
    puts @name.inspect         #---> prints nil
    puts "--------------------"
    # blah blah
  end

Basically, all the variables are nil when I try to access them but they are correctly saved into the object instance.

What am I doing wrong? How can I fix this?

Thanks in advance.

Edit : The controller

  def detail_product
    @p = Product.find(params[:product_id]) if params[:product_id].present?
    if !@p.present? then
      flash[:error] = 'No product id'
      redirect_to  :action => :products
    end
  end

Just for the sake of it, try to remove the attr readers/attr accessors if the attributes :name, :age, and :price are saved in the database — Zippie, Nov 25 '13 at 14:14
Another thing to note is that it may be possible that you never filled `@name` in, unless you're expecting Rails to do it automagically from the database. — Jeremy Rodi, Nov 25 '13 at 14:15
@Zippie Your solution works. Why?! Anyway, I need to have something like `attr_reader` for database migrations etc... So what should I use instead of `attr_reader` ? — Pol0nium, Nov 25 '13 at 14:16
no you don't, i believe Rails sets the attr readers and attr writters, so you're all set to go — Zippie, Nov 25 '13 at 14:18
@Zippie Thank you for that but do you have any documentation refering to that? :) — Pol0nium, Nov 25 '13 at 14:41
@Zippie <3 you should create an answer and I'll validate it. — Pol0nium, Nov 25 '13 at 15:06

score 8 · Accepted Answer · edited May 23 '17 at 12:01

8

Remove the attr_readers/attr_accessors if the attributes :name, :age, and :price are saved in the database, since Rails defines those methods already.

For more check this answer: https://stackoverflow.com/a/14452353/1279707

edited May 23 '17 at 12:01

Community

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answered Nov 25 '13 at 15:11

Zippie

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attr_accessor and attr_reader not working in Rails 4

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