Ruby Development and MongoMapper (John Nunemaker)

MongoMapper
Mapping Ruby To and From Mongo

MongoSF San Francisco, CA John Nunemaker
April 30, 2010 Ordered List

class Item
include MongoMapper::Document
end

class Datum
include MongoMapper::EmbeddedDocument
end

Free Stu
Persistence
Validations [presence, length, inclusion, ...]

Free Stu
Persistence

Callbacks [before/after validate, create, save, ...]

Free Stu
Persistence


Associations [many, belongs_to, one, ...]

Free Stu
Persistence


Associations [many, belongs_to, one, ...]

Serialization [to_json]

Persistence
Never gonna give you up

item = Item.create({
:title => 'MongoSF',
:location => 'San Fran',
:when => Time.now
})

puts item.to_mongo

{
"_id" => ObjectID('4bd8cc5cbcd1b313b3000001'),
"title" => "MongoSF",
"location" => "San Fran",
"when" => Wed Apr 28 17:01:32 -0700 2010
}

item = Item.new
item[:title] = 'MongoSF'
item[:location] = 'San Fran'
item[:when] = Time.now
item.save

class Item

key :title, String
key :path, String
end

Instead of database schema

Think App Schema

Built-in Types
Array, Binary, Boolean, Date, Float, Hash,
Integer, Nil, ObjectId, Set, String, Time

Custom Types
Its shake and bake and I helped!

class Set
def self.to_mongo(value)
value.to_a
end

def self.from_mongo(value)
Set.new(value || [])
end
end

class DowncasedString
def self.to_mongo(value)
value.nil? ? nil : value.to_s.downcase
end

def self.from_mongo(value)
value.nil? ? nil : value.to_s.downcase
end
end

class User

key :email, DowncasedString
end

Typeless
I do not know who I am

class Foo
key :bar
end

foo = Foo.new

foo.bar = 'Some text'
# foo.bar => "Some text"

foo.bar = 24
# foo.bar => 24

Validations
Currently using fork of validatable

class Item

key :title, String
validates_presence_of :title
end

class Item

key :title, String, :required => true
end

validates_presence_of
validates_length_of
validates_format_of
validates_numericality_of
validates_acceptance_of
validates_confirmation_of
validates_inclusion_of
validates_exclusion_of

Callbacks
Ripped from AS2’s cold, dead ﬁngers

class Item

key :title, String
key :path, String
key :parent_id, ObjectId
belongs_to :parent

before_validation :set_path

private
def set_path
self.path = parent.path + title.parameterize
end
end

:before_save, :after_save,
:before_create, :after_create,
:before_update, :after_update,
:before_validation, :after_validation,
:before_validation_on_create, :after_validation_on_create,
:before_validation_on_update, :after_validation_on_update,
:before_destroy, :after_destroy,
:validate_on_create, :validate_on_update,
:validate

to Docs
belongs_to, one, many, many :in

class Account

many :sites
end

class Site

key :account_id, ObjectId
belongs_to :account
end

account = Account.create(:title => 'OL', :sites => [
Site.new(:title => 'OL', :domain => 'orderedlist.com'),
Site.new(:title => 'RT', :domain => 'railstips.org'),
])

[
{
'_id' => ObjectID('...'),
'title' => 'OL',
'domain' => 'orderedlist.com'
'account_id' => ObjectID('...'),
},
{
'title' => 'RT',
'domain' => 'railstips.org'
'account_id' => ObjectID('...'),
}
]

class Item

many :data
end

class Datum
include MongoMapper::EmbeddedDocument

key :key, String
key :value
end

Item.create(:title => 'MongoSF', :data => [
Datum.new(:key => 'description', :value => 'Awesome.')
])

{
'title' => 'MongoSF',
'data' => [
{
'key' => 'description'
'value' => 'Awesome.',
}
]
}

Plugins
Conventional way to extend

MongoMapper is

Powered by Plugins
associations, callbacks, clone, descendants,
dirty, equality, identity_map, inspect, keys,
logger, modiﬁers, pagination, persistence,
protected, rails, serialization, timestamps,
userstamps, validations

Ruby Development and MongoMapper (John Nunemaker)

module MongoMapper
module Plugins
def plugins
@plugins ||= []
end

def plugin(mod)
extend mod::ClassMethods if mod.const_defined?(:ClassMethods)
include mod::InstanceMethods if mod.const_defined?(:InstanceMethods)
mod.configure(self) if mod.respond_to?(:configure)
plugins << mod
end
end
end

module ActsAsListFu
module ClassMethods
def reorder(ids)
# reorder ids...
end
end

module InstanceMethods
def move_to_top
# move to top
end
end

def self.configure(model)
model.key :position, Integer, :default => 1
end
end

class Foo
plugin ActsAsListFu
end

Foo.reorder(...)
Foo.new.move_to_top

Good Example
Joint: github.com/jnunemaker/joint

class Asset
plugin Joint

attachment :image
attachment :file
end

asset = Asset.create({
:image => File.open('john.jpg', 'r'),
:file => File.open('foo.txt', 'r'),
})

asset.image.id
asset.image.name
asset.image.type
asset.image.size
asset.image.read

Descendant Appends
Fancy Schmancy and Stolen

module FancySchmancy
def some_method
puts 'some method'
end
end

MongoMapper::Document.append_extensions(FancySchmancy)

class Foo
end

Foo.some_method # puts 'some method'
Foo.new.some_method # NoMethodError

def some_method
puts 'some method'
end
end

MongoMapper::Document.append_inclusions(FancySchmancy)

class Foo
end

Foo.new.some_method # puts 'some method'
Foo.some_method # NoMethodError

def some_method
puts 'some method'
end
end

class Foo
end

MongoMapper::Document.append_extensions(FancySchmancy)

class Bar
end

Foo.some_method # puts 'some method'
Bar.some_method # puts 'some method'

module IdentityMapAddition
def self.included(model)
model.plugin MongoMapper::Plugins::IdentityMap
end
end

MongoMapper::Document.append_inclusions(IdentityMapAddition)

Active Model
Validations, callbacks, serialization, etc.

Blank Document
Mix and match whatever you want

Mongo::Query
Fancy query magic for the ruby driver
github.com/jnunemaker/mongo-query

Thank you!
john@orderedlist.com
@jnunemaker

MongoSF San Francisco, CA John Nunemaker
April 30, 2010 Ordered List

Ruby Development and MongoMapper (John Nunemaker)

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