Friday, November 14, 2014

Installing Cassandra on Digital Ocean

Recently I had a chance to install cassandra on a three node cluster out on Digital Ocean. Here are my steps in a handy markdown gist. YMMV

Wednesday, May 7, 2014

Testing a Rails/Ember app with Teaspoon & QUnit and watching the tests run

Recently I have had to start working with an Ember application. It is certainly a challenge. For Unit testing we decided to look at QUnit for our front end pieces. Being used to:
and looking at tests running visually I was a bit stymied until I realized you could use the `-d` flag to override the phantom.js we set up in the config. So:
teaspoon -d selenium
will run the tests with Firefox & Selenium (normal version issues apply)

Wednesday, February 26, 2014

Using table_for with HTML elements in Active Admin

Ah yes another foray into ActiveAdmin. Recently I needed to use the table_for feature on a show page and add some html options to it. This required looking into the code itself as the documentation was not exactly clear in either ActiveAdmin or Arbre. Essentially you need to do something like this:
    table_for agent.quotes, {:id => 'agent_quotes'} do
      column 'Quote Number' do |quote|
      column 'Business' do |quote|
      column 'Status' do |quote|
      column '' do |quote|
        link_to 'View Quote', admin_quote_path(
It was as simple as adding a hash with the needed items after the collection for the table_for:
table_for collection, {:id => 'html_id', :class => 'html_class'}

Tuesday, July 9, 2013

Uploading CSV files to a Rails Application using ActiveAdmin

Recently I had try and upload CSV files to a rails application via Active Admin. I had the inkling that maybe I was not the first to have done this. A short google search later and I was lead to this answer on Stack Overflow

I loved it except for the processing class listed under csv_db. It seemed too limiting in that it requires EVERY column to be there whether data is present or not. I recalled a Railscast that offered up a much more flexible solution and created this:

require 'csv'
class CsvDb
  class << self
    def convert_save(model_name, csv_data)
        target_model = model_name.classify.constantize
        CSV.foreach(csv_data.path, :headers => true) do |row|
      rescue Exception => e
        Rails.logger.error e.message
        Rails.logger.error e.backtrace.join("\n")

If you replace the code from the Stackoverflow post in csv_db with this you should be able to load any number of columns you wish. As soon as I figure out the updating of existing records I will post a follow-up.

Sunday, April 28, 2013

Flay, a gem to help improve the maintainability of your code

Recently I read a post where the author listed the must have gems for rails development. Being an avid watcher of Railscasts I knew many of them however one, flay, caught my attention. It comes out of the Seattle Ruby group which also brought us flog.

Flay is along the same lines as Flog; it analyzes your code looking for issues. Rather than looking for tortured code though it is looking for similar or duplicate code blocks. You install with `gem install flay` and then run it against your files, e.g.:

flay ./app/models/*.rb

A report is generated of the suspect areas like this:

macscott:test-project scottshea$ flay ./app/models/*.rb
Total score (lower is better) = 1666

1) Similar code found in :call (mass = 170)

2) Similar code found in :defs (mass = 154)

3) Similar code found in :defs (mass = 138)

4) Similar code found in :call (mass = 136)

5) IDENTICAL code found in :defn (mass*2 = 128)

6) IDENTICAL code found in :defn (mass*2 = 120)


The total app score of 1666 can be viewed in its individual components showing areas that provide the most bang for the buck. For experienced developers operating on their own or in a small team Flay may be unnecessary. However, on larger projects (as the one I ran it on) or those with beginner or intermediate programmers it can help increase the maintainability of your codebase.

I am not sure where the 1666 would rank on the overall chart (is that really bad? representative?) but the 'lower is better' advice holds true. This Stackoverflow question offers some interpretation of the score but really the best advice is "don't let it get higher!"

Monday, April 22, 2013

A rake task to automate deployment and database migration to Heroku

One of my major annoyances with Heroku is that the deploy does not automatically run any database migrations. Seriously?! So I ran into this tonight when I am trying to explain to a seasoned SA that while Heroku automatically will recompile your assets for you it will not do the migrations. A Google turned up this Stackoverflow question which in turn led to this gist. And I am excited to be trying it out.

Saturday, April 20, 2013

Using Sidekiq with Faye to notify client web pages and applications of updates

Recently I was given a small coding challenge of how I would update sites & client applicaitons with notifications of content being released. My mind immediately flew to the faye gem. However, this would be a serious block if my app had to halt everything to send out the notification to a bunch of browsers. So, I added in Sidekiq. In the Content Model I put this to call out to Sidekiq:
  def self.release_next
The ContentWorker then looks like this:
class ContentWorker
  include Sidekiq::Worker
  sidekiq_options queue: "content"

  def perform
    next_release = Content.next_release(Content.last_release)
    # puts the data into JSON format; for actual content it could encode a url that is then loaded
    vars = ["title" => next_release.title,
             "site" =>,
             "released_at" => next_release.released_at.strftime("%l:%M:%S %p %m-%d-%Y")].to_json
    message = {:channel => "/releases", :data => vars, :ext => {:auth_token => FAYE_TOKEN}}

    Net::HTTP.post_form(uri, :message => message.to_json)
I created a designated queue in Sidekiq for the messages and then made the Faye channel creation configurable via an environment variable from an initializer file (/config/initializers/faye_configuration.rb):
FAYE_SUBSCRIPTION_PATH = "http://localhost:9292/faye"
The client then just listens in on the Faye channel and acts upon a message coming through. Here is the Javascript I wrote for listening to the Channel and adding the new release to the top of the view table just below the headers:
$(function() {
   var faye = new Faye.Client("");
   faye.subscribe("/releases", function(data) {

function add_to_table(data){
    var json_obj = jQuery.parseJSON(data);
    var $content_table = $('#content_table');
    if ($content_table.find('tr').length >= 10 ) {
    $("#header").after("<tr><td>" + json_obj[0].title+ "</td><td>" + json_obj[0].site + "</td><td>" + json_obj[0].released_at + "</td></tr>");
All in all a nice little challenge. I have not had a chance to try it out beyond my home network yet so I am not sure how performant the solution would be.

Railscasts used for this: