scriptonia

Print grape routes using rake task.

Use http_basic with grape API layer.

Migrating s3 data to the new account

Few days ago I needed to migrate s3 data from one account to another account. I’ve decided to use as background worker heroku server. And wrote this code below:

devise masquerade gem

Yesterday I published the simple gem for devise. Now it is easy to add ‘Login As’ functionality to your admin pages.

1. Add gem ‘devise_masquerade’ to your Gemfile.

2. Add before_filter :masquerade_user! to the application_controller.rb

3. Add link_to ‘Login As’, masquerade_path(user) to your table with users.

4. Use it :)

More

deploy branch to the heroku

git push heroku branch-name:master

print sql queries in the console while debugging

rails code:

   class Post < ActiveRecord::Base
     def method1
       require 'ruby-debug'
       debugger
       ...
     end
   end

In the debug session you should run the next following code:

  ActiveRecord::Base.logger = Logger.new($stdout)

My ~/.rdebugrc

set autolist
set autoeval
set autoreload

ActiveRecord aggregation functions a quick trick.

Today I found a very interesting trick connection with aggregation functions in the ActiveRecord.

For example you have a Stat(clicks:integer(default: 0), key:string) model. And you need to find sum of the clicks for the specific key.

Stat.where(:key => 'your key').all(:select => "sum(clicks) as clicks")

Lets imagine you have the stats with key. And as result of expression you will get stat object with clicks.

[#<Stat clicks: 102>] 

But if you have no the stats with key:

Stat.where(:key => 'your key').count => 0

Lets the same expression for finding summary of the clicks:

Stat.where(:key => ‘your key’).all(:select => “sum(clicks) as clicks”)

[#<Stat clicks: nil>] 

As I wrote above clicks should have default value as 0. And you are making something like report page, you don’t want to add to_i for nil objects to the different expressions.

I wrote a small patch for this behavior:

module Extensions
  module DefaultAttributeValue
    def self.included(base)
      base.send :extend, ClassMethods
    end

    module ClassMethods
      def default_attribute_value(key, value)
        self.class_eval %Q{
          def #{key}
            value = read_attribute(:#{key})

            value || #{value}
          end
        }
      end
    end
  end
end


# specs

require 'spec_helper'

class TestClass
  include Extensions::DefaultAttributeValue

  attr_accessor :key

  default_attribute_value :key, 0

  def read_attribute(key)
    instance_variable_get("@#{key}")
  end
end

describe Extensions::DefaultAttributeValue do
  let(:object) { TestClass.new }

  it { object.key.should == 0 }

  context 'when key assigned' do
    before { object.key = 1 }

    it { object.key.should == 1 }
  end
end

# example

class Stat #< ActiveRecord::Base
  include Extensions::DefaultAttributeValue

  default_attribute_value :clicks, 0
end

Gist