MongoDB and Ruby - Speaker Deck

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MongoDB A NoSQL DB Story

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@DeLongShot Developer, Elevator Up

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Why MongoDB? Overview

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John Nunemaker GitHub, Gauges, Speaker Deck, Harmony App “Whereas SQL is about normalizing the storage of data and then flexibly querying it, NoSQL is about thinking how you will query data and then flexibly storing it.”

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Fun NoSQL! Schema-less (Can be) Very Fast >> Writes >> Reads Scaling

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Not So Fun Joins ACID transactions NoSQL

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What is MongoDB? Overview

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Document-based BSON { Name: “John Doe”, Age: 35, Twitter: “@johndoe” }

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Collections Not Tables db.users { Name: “John Doe”, Age: 35, Twitter: “@johndoe” }, { Name: “Jane Doe”, Age: 27, Twitter: “@janedoe” }

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Embedded Documents { Name: “John Doe”, Age: 35, Twitter: “@johndoe”, address: { street: “5555 Lane Rd” city: “Wonderland” zip-code: 55555 } }

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Mongo Shell $: mongo > use rug > rug.admins.insert({name: “John Doe”}) > rug.admins.find() > {_id: 1231232, name: “John Doe”} > rug.admins.find().count() > 1

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MongoDB and Ruby Overview

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Ruby Driver gem install mongo gem install bson

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ODMs in a ORM World MongoMapper Mongoid Mongomatic MongoODM MongoModel High-level modeling functions > Validations > Associations Gems

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Mongoid gem ‘mongoid’ Associations embedded_in embeds_many has_many belongs_to Columns field

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Embedded v. Linking Embedded Use “embeds_in” Included in one query Linking Use “has_many” Reference to parent in foreign key Requires another query

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When to use? Embedded When children are finite/more certain number Linking Unsure of number of children

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class Quiz includes Mongoid::Document field :name has_many :results embeds_many :questions end

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class Question includes Mongoid::Document field :question_number field :copy embedded_in :quiz embeds_many :answers end

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class Answer includes Mongoid::Document field :copy embedded_in :question end

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#one query quiz = Quiz.find(1) quiz.questions >> returns questions [] question = questions.first >> returns question answers = question.answers.first >> returns answer