jcasimir

Transactions

As your business logic gets complex you may need to implement transactions. The classic example is a bank funds transfer from account A to account B. If the withdrawal from account A fails then the deposit to account B should either never take place or be rolled back.

Basics

All the complexity is handled by ActiveRecord::Transactions. Any model class or instance has a method named .transaction. When called and passed a block, that block will be executed inside a database transaction. If there's an exception raised, the transaction will automatically be rolled back.

Example

benedikt

# encoding: UTF-8

Capistrano::Configuration.instance(:must_exist).load do
  namespace :rails do
    desc "Open the rails console on one of the remote servers"
    task :console, :roles => :app do
      hostname = find_servers_for_task(current_task).first
      exec "ssh -l #{user} #{hostname} -t 'source ~/.profile && #{current_path}/script/rails c #{rails_env}'"
    end
  end

dandorman

require 'spec_helper'

describe FeaturePool do
  it "creates a new instance given valid attributes" do
    Fabricate :feature_pool
  end

  it "is not valid without a name" do
    Fabricate.build(:feature_pool, :name => "").should_not be_valid
  end

runemadsen

Polymorphic Associations reversed

It's pretty easy to do polymorphic associations in Rails: A Picture can belong to either a BlogPost or an Article. But what if you need the relationship the other way around? A Picture, a Text and a Video can belong to an Article, and that article can find all media by calling @article.media

This example shows how to create an ArticleElement join model that handles the polymorphic relationship. To add fields that are common to all polymorphic models, add fields to the join model.

jwo

class Api::RegistrationsController < Api::BaseController
  
  respond_to :json
  def create

    user = User.new(params[:user])
    if user.save
      render :json=> user.as_json(:auth_token=>user.authentication_token, :email=>user.email), :status=>201
      return
    else

bsodmike

Implement Routing for Subdomains

Rails 3.0 introduced support for routing constrained by subdomains.

A subdomain can be specified explicitly, like this:

match '/' => 'home#index', :constraints => { :subdomain => 'www' } 

sumskyi

GeoEntity.last

SELECT geo_entities.* FROM geo_entities ORDER BY geo_entities.id DESC LIMIT 1

returns:

County id: 4, eid: nil, pid: nil, ename: nil, etype: 2, created_at: "2011-11-21 06:26:37", updated_at: "2011-11-21 06:26:37"

febuiles

#!/bin/sh

# This assumes you have:
# 1) A user called `hubot` in charge of the bot.
# 2) A file called /home/hubot/.hubotrc that contains the Hubot credentials.
#
# To set the adapter either edit bin/hubot to specify what you want or append
# `-- -a campfire` to the $DAEMON variable below.
#
### BEGIN INIT INFO

lucatironi

# Server App
# This file must be in lib/myapp/api.rb
module MyApp
  module Entities
    class Products < Grape::Entity
      expose :id, :code, :name, :short_description
      expose :description, :unless => { :collection => true }
      expose (:category) { |model, options| model.category.name }
      expose (:brand) { |model, options| model.brand.name }
    end

cklanac

/***********************************************************************************************************************
***********************************************************************************************************************
* CONTENTS: 
* Native Object
* Object Literal
* Basic Object
* Psuedo-Class
* Self Executing/Invoking Structure
* Lazy Function
* Module Pattern