Extending ActiveRecord::Base

Question

I'm trying to add some custom methods to ActiveRecord. I want to add a *_after and *_before scopes for every date field of a model so I can do something like this:

User.created_at_after(DateTime.now - 3.days).created_at_before(DateTime.now)

I've followed the solution explained here Rails extending ActiveRecord::Base but when I execute the rails console and try to call the methods I get an undefined method error.

Here's my code:

# config/initializers/active_record_date_extension.rb
require "active_record_date_extension"

# lib/active_record_date_extension.rb
module ActiveRecordDateExtension
  extend ActiveSupport::Concern

  included do |base|
    base.columns_hash.each do |column_name,column|
      if ["datetime","date"].include? column.type
        base.define_method("#{column_name}_after") do |date|
          where("#{column_name} > ?", date)
        end
        base.define_method("#{column_name}_before") do |date|
          where("#{column_name} < ?", date)
        end
      end
    end
  end
end
Rails.application.eager_load!

ActiveRecord::Base.descendants.each do |model|
  model.send(:include, ActiveRecordDateExtension)
end

What am I doing wrong?

Answer 1

Using Rails 4.1.9 and Ruby 2.2.1, I noticed a few issues with the code above.

1. You are comparing column.type with strings, and Rails returns symbols for that attribute.
2. base.define_method is trying to call a private method, you can get around that with send

This is the tweaked code

module ActiveRecordDateExtension
  extend ActiveSupport::Concern

  included do |base|
    base.columns_hash.each do |column_name,column|      
      if [:datetime, :date].include? column.type              
        base.class.send(:define_method, "#{column_name}_after") do |date|
          where("#{column_name} > ?", date)
        end
        base.class.send(:define_method, "#{column_name}_before") do |date|
          where("#{column_name} < ?", date)
        end
      end
    end
  end
end