Rails with MongoDB - RORLab 47th Oct 8, 2013

1. Rails with MongoDB-2
Eugene Park
starville@me.com

2. Setup Ruby On Rails
on Ubuntu 13.04
• Installing Ruby with rvm
• Installing Rails
$ sudo apt-get update
$ Sudo apt-get install curl
$ curl -L https://get.rvm.io | bash -s stable
$ source ~/.rvm/scripts/rvm
$ rvm requriements
$ Sudo apt-get ...
$ rvm install 2.0.0
$ rvm use 2.0.0 --default
$ ruby -v
$ gem install rails

3. Installing MongoDB
on Ubuntu 13.04
• Configure Package Management System (APT)
• Install Packages
• configration
$ sudo apt-key adv --keyserver
hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10
$ echo 'deb http://downloads-
distro.mongodb.org/repo/ubuntu-upstart dist
10gen' | sudo tee
/etc/apt/sources.list.d/mongodb.list
$ sudo apt-get update
$ sudo apt-get install mongodb-10gen
$ whereis mongodb.conf

4. Installing mongoid
• installing Mongoid is with bundler
• Configuration
$ vi Gemfile
gem 'mongoid', github: 'mongoid/mongoid‘
gem 'bson', github: 'mongodb/bson-ruby'
gem 'execjs‘
gem 'therubyracer‘
$ bundle update
$ Rails g mongoid:config
$ vi myapp/config/mongoid.yml

5. MongoDB SQL
Create Insert (Save) Insert
Read Find Select
Update Update (Upsert) Update
Delete Remove Delete
CRUD & the Mongoshell

6. book = {
_id : 10203040,
title : “Rails wth MongoDB Guide”,
auther : “Eugene Park”,
available : 987,
checkout : [ {by : “Eugene”, date : ISOdate(“2013-10-01”)}]
}
db.books.findAndModify({
query: {
_id : 10203040,
available: { $gt: 0 }
},
update: {
$inc : { available : -1},
$push : { checkout : { by: “Crayon”, data: new Date()}}
}
})
Atomic operations

7. Schema Design
• The data your application needs.
• How your application will read the data.
• How your application will write the data.
Traditional MongoDB
Your application doesn’t matter.
Only about the data.
Only relevant during design.
It’s always about your application.
Not only about the data, but also
how it’s used.
Relevant during the lifetime of your
application.

8. Blog data model
posts
id
author
title
Body
comments
id
post_id
tag_id
author
body
posts_tags
id
post_id
tag_id
tags
id
text
posts
id
title
body
tags[]
comment[
{author: …,body: …},
{…}
]
RDBMS MongoDB

9. Create blog apps
$ rails new blog –-skip-active-record
$ cd blog
$ vi Gemfile
#add and save
gem 'mongoid', github: 'mongoid/mongoid‘
gem 'bson', github: 'mongodb/bson-ruby'
gem 'execjs‘
gem 'therubyracer‘
$ bundle
$ rake g mongoid:config
$ rails g scaffold post title:string body:text tags:array
... ① string to array
$ Rails g model comment author:string body:text
... ② def relationship, routes
$ rails g controller comments
... ③ def create
... ④ create list, form for comment