Reopen Impression Class from Impressionist Gem in Rails 4

Question

I'm trying to modify the Impressionist gem class "Impression" to no avail.

I've tried the following:

class Impression
  def hello
    "world"
  end
end

Impression.class_eval do
end

both in: /app/models/impression.rb and /lib/impression.rb (with correct configuration to include this folder)

What am I doing wrong? I'm using Rails 4. Ideally, I'd like to add an active record association and add some helper methods.

Answer 1

If you're overriding a class provided by a gem, you will need to manually require your version to get your changes included. This is usually done in an initializer.

Answer 2

i assume that you are talking about this gem: https://github.com/charlotte-ruby/impressionist and want to change the model class Impression.

from what i can see it is supposed to be a rails engine.

rails engines use to be namespaced, a stack-trace might have revealed this.

did you try this?

# app/extensions/impressionist/impression.rb
module Impressionist
  class Impression
    def hello
      "world"
    end
  end
end

you could also try putting your code in an initializer, because it might also be a load order problem.

Answer 3

Try this:

require Impressionist::Engine.root.join('lib/impressionist/models/active_record/impression')

class Impression
  def hello
    "world"
  end
end

Answer 4

Extending a model class with your own methods should be done using a concern. Try putting this in a file in your lib folder and require it in an initializer:

require Impressionist::Engine.root.join('lib/impressionist/models/active_record/impression')

module ImpressionExtensions
  extend ActiveSupport::Concern

  def some_instance_method
    # do some stuff
  end

  module ClassMethods
    def some_class_method
      # do some stuff
    end
  end

end

Impression.send(:include, ImpressionExtensions)

Adding methods to any model should be done in a similar manner. The way Impressionist works is a bit different, in that it first defines the Impression class as a regular, standalone class, before overriding it and making it a model.