Question

Here is my AR Model:

class MyObject < ActiveRecord::Base
   include ContentSyntax # where parse_out_variables is defined
  serialize :variables
  def save
    self.variables = ContentSyntax.parse_out_variables(self.body)
    super
  end
end

now, in my app, I do
my_object.update_attributes(params)

which worked fine before I tried to extend save.

The Error I get is this:

TypeError (class or module required):
  app/models/my_object.rb:64:in `save'

But I want this code to execute every time the object is saved. (Or if just one attribute (the ‘body’) is changed, that would be better)

What is the right way to do this?

EDIT:

using a before_save callback:

  before_save {
    self.variables = ContentSyntax.parse_out_variables(self.body)
  }

I now have the error:

NoMethodError (undefined method `body' for #<Class:0x10a0866b8>):

but… it exists!

Answer 1

Using a before_save callback is the right way to do this. However, when you use a block with an ActiveRecord callback, the object in question is passed to the block as an argument so you’d want something more like this:

before_save { |o| o.variables = o.parse_out_variables(o.body) }

or maybe this:

before_save :add_variables

private

def add_variables
    self.variables = parse_out_variables(self.body)
end