MongoDB & Mongoid with Rails
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The document discusses MongoDB and the Mongoid ORM for Ruby. It provides examples of using Mongoid to define MongoDB document schemas and associations, perform queries, and leverage features like validation, versioning, and aggregation. Overall, the document shows how Mongoid allows developers to interact with MongoDB documents in a similar way to ActiveRecord while taking advantage of MongoDB's flexible document data model.
![Associations in Mongoid
class Post
include Mongoid::Document
field :title, :type => String
field :body, :type => String
has_many :comments
end
class Comment
include Mongoid::Document
field :rant, :type => String
belongs_to :post, :inverse_of => :comments
end
This creates an Embedded Document.
@posts = @db.collection('posts')
@document = {:title => "MongoDB on Rails",
:body => "Revelatory! Loved it!",
:comments => [{:rant => “I completely disagree”}]
}
@posts.save(@document)](https://image.slidesharecdn.com/mongodb-100120142350-phpapp02/85/MongoDB-Mongoid-with-Rails-11-320.jpg)
![Keys, Validations, Timestamps & Hooks
class Post
include Mongoid::Document
include Mongoid::Timestamps
field :title, :type => String
field :body, :type => String
field :slug, :type => String
has_many :comments
has_key :title, :unique => true # “Audi IMS” becomes “audiims”
validates_presence_of :title, :body
validates_unqiueness_of :title
before_save :set_slug
def set_slug
self.slug = “#{title.parameterize}-#{body[0..3]}”
end
end](https://image.slidesharecdn.com/mongodb-100120142350-phpapp02/85/MongoDB-Mongoid-with-Rails-12-320.jpg)
![Versioning a Mongo Document
class Post
include Mongoid::Document
include Mongoid::Timestamps
include Mongoid::Versioning
field :title, :type => String
field :body, :type => String
field :slug, :type => String
has_many :comments
has_key :title, :unique => true # “Audi IMS” becomes “audiims”
validates_presence_of :title, :body
validates_unqiueness_of :title
before_save :set_slug
def set_slug
self.slug = “#{title.parameterize}-#{body[0..3]}”
end
end](https://image.slidesharecdn.com/mongodb-100120142350-phpapp02/85/MongoDB-Mongoid-with-Rails-13-320.jpg)
![fuck SQL! Criteria is the shit.
Criteria#all - perform exact matches
Post.criteria.all(:title => [ “Rails”, “2.3” ])
Criteria#find - match key/value
Post.criteria.and(:created_at.gt => 2.months.ago)
Criteria#exclude
Post.criteria.exclude(:created_at => Date.today)
Criteria#id - match document id
Post.criteria.id(“4b2fe28ee2dc9b5f7b000029”)
Criteria#in - match any of the values in an array
Post.criteria.in(:title => [“Merb”, “Rails”, “Ruby”]
Criteria#order_by
Post.criteria.order_by([[:created_at, :desc], [:title, :asc] ])
Criteria also has #limit, #not_in, #only, #skip](https://image.slidesharecdn.com/mongodb-100120142350-phpapp02/85/MongoDB-Mongoid-with-Rails-16-320.jpg)
![You can chain any of the Criteria API
Post.in(:title => [“Rails”, “Ruby”]).where(:created_at.gt => 2.months.ago).skip(10)
class Post
include Mongoid::Document
class << self
def ruby_related
criteria.in(:title => [“Ruby”, “Rails”])
end
def in_last_two_months
criteria.where(:created_at.gt => 2.months.ago))
end
end
end
Post.ruby_related.in_last_two_months](https://image.slidesharecdn.com/mongodb-100120142350-phpapp02/85/MongoDB-Mongoid-with-Rails-19-320.jpg)
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MongoDB & Mongoid with Rails
- 1. MongoDB { name: “mongo”, type: “db” }
- 2. “MongoDB is designed to be human-oriented. It reduces the burden of programming. It tries to push jobs back to machines. You can accomplish more tasks with less work, in smaller yet readable code.” - Banker
- 3. built for speed document/collection oriented dynamic queries and indexes replication and failover
- 4. websites from yesterday and today high volume traffic high scalability storage of objects and JSON
- 5. caveats
- 8. MongoDB with Ruby because we all want ActiveRecord...
- 9. mongo-ruby-driver mongomapper mongoid
- 10. Spiff uses Mongoid class Post include Mongoid::Document field :title, :type => String field :body, :type => String end @posts = @db.collection('posts') @document = {:title => "MongoDB on Rails", :body => "Revelatory! Loved it!"} @posts.save(@document)
- 11. Associations in Mongoid class Post include Mongoid::Document field :title, :type => String field :body, :type => String has_many :comments end class Comment include Mongoid::Document field :rant, :type => String belongs_to :post, :inverse_of => :comments end This creates an Embedded Document. @posts = @db.collection('posts') @document = {:title => "MongoDB on Rails", :body => "Revelatory! Loved it!", :comments => [{:rant => “I completely disagree”}] } @posts.save(@document)
- 12. Keys, Validations, Timestamps & Hooks class Post include Mongoid::Document include Mongoid::Timestamps field :title, :type => String field :body, :type => String field :slug, :type => String has_many :comments has_key :title, :unique => true # “Audi IMS” becomes “audiims” validates_presence_of :title, :body validates_unqiueness_of :title before_save :set_slug def set_slug self.slug = “#{title.parameterize}-#{body[0..3]}” end end
- 13. Versioning a Mongo Document class Post include Mongoid::Document include Mongoid::Timestamps include Mongoid::Versioning field :title, :type => String field :body, :type => String field :slug, :type => String has_many :comments has_key :title, :unique => true # “Audi IMS” becomes “audiims” validates_presence_of :title, :body validates_unqiueness_of :title before_save :set_slug def set_slug self.slug = “#{title.parameterize}-#{body[0..3]}” end end
- 14. Access related items class Post include Mongoid::Document include Mongoid::Timestamps include Mongoid::Versioning field :title, :type => String field :body, :type => String field :slug, :type => String has_many :comments belongs_to_related :account has_many_related :sources ..... end database.yml meet database.mongo.yml
- 15. But does it blend? Post.all(:conditions => { :title => “Rails 2.3” }) Post.find(:all, ...) Post.first(...) Post.find_or_create_by(:title => “Merb is dead”) Post.find_or_initialize_by(...) Associations: @post.comments.all
- 16. fuck SQL! Criteria is the shit. Criteria#all - perform exact matches Post.criteria.all(:title => [ “Rails”, “2.3” ]) Criteria#find - match key/value Post.criteria.and(:created_at.gt => 2.months.ago) Criteria#exclude Post.criteria.exclude(:created_at => Date.today) Criteria#id - match document id Post.criteria.id(“4b2fe28ee2dc9b5f7b000029”) Criteria#in - match any of the values in an array Post.criteria.in(:title => [“Merb”, “Rails”, “Ruby”] Criteria#order_by Post.criteria.order_by([[:created_at, :desc], [:title, :asc] ]) Criteria also has #limit, #not_in, #only, #skip
- 17. arithmetic, grouping & aggregation #max, #min, #sum, #aggregate, #group
- 18. “But what about named scopes dude?!” -Gabe named_scope :active, criteria.where(:active => true) do def count size end end named_scope :inactive, :where => { :active => false } named_scope :frags_over, lambda { |count| { :where => { :frags.gt => count } } } named_scope :deaths_under, lambda { |count| criteria.where(:deaths.lt => count) }
- 19. You can chain any of the Criteria API Post.in(:title => [“Rails”, “Ruby”]).where(:created_at.gt => 2.months.ago).skip(10) class Post include Mongoid::Document class << self def ruby_related criteria.in(:title => [“Ruby”, “Rails”]) end def in_last_two_months criteria.where(:created_at.gt => 2.months.ago)) end end end Post.ruby_related.in_last_two_months
- 20. additional mongoid features Composite Keys Indexing Inheritance native MongoDB expressions