Sinatra, Datamapper, Sass and Heroku

Here are a few notes on a simple prototype I just built with Sinatra, deploying on Heroku. It’s easy, but like everything (it seems) there are always a few tricks you need to remember.

To start, here’s an edited listing of my pthingy project directory (pthingy stands for phonethingy). The main ruby file is pthingy.rb. It essentially contains everything except the templates which are in the views directory.

doug@zeus ~/code/spikes/pthingy (master)
$ la
doug@zeus ~/code/spikes/pthingy (master)


Note you have to require libraries explicitly such as haml and sass. For datamapper, you can require just the specific libraries you need or the big kahuna: datamapper.

require 'rubygems'
require 'sinatra'
require 'dm-core'
require 'dm-timestamps'
require 'haml'
require 'sass'


The keys here include requiring the correct libraries you need as well as performing a setup. Note the class definitions include the association assignments.

## Models / DB
# If you want the logs displayed you have to do this before the call to setup$stdout, :debug)

DataMapper.setup(:default, ENV['DATABASE_URL'] || "sqlite3://#{Dir.pwd}/pthingy.db")
configure :development do
  enable :logging, :dump_errors, :raise_errors

# log ="sinatra.log", "a")
# STDOUT.reopen(log)
# STDERR.reopen(log)

class Event
  include DataMapper::Resource

  property :id,         Serial   # An auto-increment integer key
  property :event_tag,  String   # An event key string.
  property :created_at, DateTime # A DateTime, for any date you might like.

  has n, :posts


class Post
  include DataMapper::Resource

  property :id,         Serial   # An auto-increment integer key
  property :url,        Text     # URL of image.
  property :created_at, DateTime # A DateTime, for any date you might like.

  belongs_to :event
  has n, :comments


class Comment
  include DataMapper::Resource

  property :id,         Serial
  property :posted_by,  String   # IP address of submitter
  property :body,       Text
  property :created_at, DateTime # A DateTime, for any date you might like.

  belongs_to :post


require  'dm-migrations'
# Create or upgrade all tables at once, like magic
# DataMapper.auto_upgrade!

Need to go back and see about auto-upgrade!


You can set the default format with the set command. You can set utf-8 for content in a before filter. You can use the haml command to render haml views.

set :haml, {:format => :html5 } # default Haml format is :xhtml

# filter
# set utf-8 for outgoing
before do
 headers "Content-Type" => "text/html; charset=utf-8"

## Handlers
get '/' do
 haml :root


Helpers for views can be added and used in a similar way as Rails.

helpers do
  def post_image(post)
    url = post.url
    image_str = "<img src=" + url + '>'
    "<a href='/comments/" + + "'>" + image_str + "</a>"

  def how_long_ago(comment)
    diff = - comment.created_at
    hours, mins, secs, ignore_fractions = Date::day_fraction_to_time(diff)
    "%02d:%02d" % [ mins, secs ] + " minutes ago:"


I stumbled a bit on setting this up. There are some incorrect posts out there. This worked for me. NOTE: the styles.sass file goes in the ./views directory.

get '/style.css' do
  content_type 'text/css', :charset => 'utf-8'
  sass :style


.gem file

Ok, now to publish on heroku. The first thing to do is create a .gems file in the project directory. While most of these things are very straight forward, you have to add a database adapter. In the case of Heroku that means postgres.Note that in development I was using sqlite3.

Caveat: I don’t think you need to specify both the datamapper library and it’s individual libraries.

sinatra -v 1.0
dm-core --version 1.0.0
dm-timestamps --version 1.0.0
dm-migrations --version 1.0.0
haml --version 3.0.9

Nothing complicated required here.

require 'pthingy'
run Sinatra::Application

And that’s it! It should work….

As long as you didn’t do something wrong, of course.


This entry was posted on Wednesday, September 1st, 2010 at 11:06 am and is filed under DataMapper, HAML, Heroku, SASS, Sinatra. You can follow any responses to this entry through the RSS 2.0 feed. Responses are currently closed, but you can trackback from your own site.

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18 Responses to ' Sinatra, Datamapper, Sass and Heroku '

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  1. 1

    on September 2nd, 2010 at 1:38 pm

    Nice post.

  2. 2
    dgoldie said,

    on September 6th, 2010 at 5:57 pm

    Hey thanks,

    especially for reminding me about the Firefox beta. I had forgotten about it. Unfortunately I can’t reproduce your issues; for me it gives me the same experience — though I am on a Mac.
    In any case, I guess it doesn’t matter, because I really can’t change much. I didn’t build this blog software — it’s actually on WordPress for the time being.

    but thanks,

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