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| == Application Setup ==
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| * create project with
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| <pre>
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| rails new my_project
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| rails -d mysql new my_project # if you don't want the default sqlite3
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| </pre>
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| * add gem dependencies to <code>Gemfile</code> at the root level
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| * update <code>config/application.rb</code> to load needed dependencies and update defaults
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| * double-check <code>/config/initializers</code> and <code>/config/environments</code>
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| * edit <code>config/database.yml</code> to connect to your database
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|
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|
| === Notes ===
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| Files in <code>lib/</code> are not automatically loaded, so you need to <code>require</code> them.
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|
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| In <code>config/environments/development.rb</code>, set
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| <pre>
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| config.action_mailer.perform_deliveries = false
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| </pre>
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| No delivery attempt is performed, but you can still see the mail in the log file to check it looks good
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|
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| == Database Setup ==
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| * create database with
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| <pre>
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| rake db:create
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| </pre>
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|
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| === Create a table and its controller ===
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| <pre>
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| rails generate model Article
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| </pre>
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| Edit <code>db/migrate/20100223220648_create_articles.rb</code> to look like this:
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| <source lang="ruby">
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| class CreateArticles < ActiveRecord::Migration
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| def self.up
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| create_table :articles do |t|
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| t.string :title
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| t.text :body
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| t.datetime :published_at
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| t.timestamps
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| end
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| end
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| def self.down
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| drop_table :articles
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| end
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| end
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| </source>
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| To create/update the table:
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| <pre>
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| rake db:migrate
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| </pre>
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| To generate the controller:
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| <pre>
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| rails generate controller articles
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| </pre>
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|
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| === Make a scaffold ===
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| To make a scaffold for the table to allow easy create/update/delete in development:
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| <pre>
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| rails generate scaffold Article title:string body:text published_at:datetime --skip-migration
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| </pre>
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| WARNING: As you develop your application, you will eventually replace most or even all of the code that the scaffold generates in the controller.
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|
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| === Update table and scaffold ===
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| To modify the table, generate a custom migration:
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| <pre>
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| rails generate migration add_excerpt_and_location_to_articles excerpt:string location:string
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| </pre>
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| creates this migration file <code>db/migrate/20100223232337_add_excerpt_and_location_to_articles.rb</code>:
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| <source lang="ruby">
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| class AddExcerptAndLocationToArticles < ActiveRecord::Migration
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| def self.up
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| add_column :articles, :excerpt, :string
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| add_column :articles, :location, :string
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| end
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| def self.down
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| remove_column :articles,
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| :excerpt remove_column :articles, :location
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| end
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| end
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| </source>
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| Run <code>rake db:migrate</code> again to update the database.
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|
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| Now update the scaffold:
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| <pre>
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| rails generate scaffold Article title:string location:string excerpt:string body:text published_at:datetime --skip-migration
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| </pre>
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|
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| === Add validations to the model ===
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| Edit <code>app/models/article.rb</code>:
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| <source lang="ruby">
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| class Article < ActiveRecord::Base
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| validates :title, :presence => true
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| validates :body, :presence => true
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| end
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| </source>
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|
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| == Other rails commands ==
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| <pre>
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| rails console
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| rails dbconsole
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| rails server
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| rails runner
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| </pre>
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|
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| == Routing ==
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| Configured in <code>config/routes.rb</code>
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| <pre>
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| match 'products/:id' => 'products#show'
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| </pre>
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| The url <code><nowiki>http://localhost:3000/products/8</nowiki></code> will be mapped to the <code>show</code> action of the <code>products</code> controller with <code>params[:id]</code> set to 8
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|
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| To create a link to this route (old way):
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| <pre>
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| link_to "Products", :controller => "products", :action => "show", :id => 1
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| </pre>
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|
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| To restrict the HTTP method, use get or post instead of match:
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| <pre>
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| get 'products/:id' => 'products#show'
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| </pre>
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|
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| To redirect:
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| <pre>
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| match "/foo", :to => redirect("/bar")
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| </pre>
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|
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| == Logging ==
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| Use these in models, views, controllers to send timestamped messages to the log.
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| <source lang="ruby">
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| logger.debug "debug message"
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| logger.info "info message"
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| logger.warn "something bad"
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| logger.error "something broke"
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| logger.fatal "application dead"
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| </source>
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|
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| == Active Record ==
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|
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| === Create and Save ===
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|
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| <source lang="ruby">
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| article = Article.new # make an empty object
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| article.title = "My Title" # add attributes
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| article.author = "Herman"
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| article.save # save to database
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| </source>
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|
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| <source lang="ruby">
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| article.create(:title => "My Title", :author => "Herman") # make, set attributes, and save
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| </source>
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|
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| <source lang="ruby">
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| article.new_record? # new means not saved to database
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| </source>
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|
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| === Find ===
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| <source lang="ruby">
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| Article.find(3) # look for id = 3
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| Article.first # same as Article.find(:first), uses "LIMIT 1" in SQL, so may not be id = 1
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| Article.last # same as Article.find(:last)
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| Article.all # same as Article.find(:all)
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| Article.where(:title => 'RailsConf').first # chaining
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| Article.find_by_title('RailsConf') # dynamic finder
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| </source>
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|
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| === Update ===
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| <source lang="ruby">
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| article = Article.first
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| article.title = "Rails 3 is great"
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| article.published_at = Time.now
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| article.save
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| </source>
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| <source lang="ruby">
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| article = Article.first
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| article.update_attributes(:title => "RailsConf2010", :published_at => 1.day.ago) # saves too
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| </source>
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|
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| === Delete ===
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| <source lang="ruby">
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| Article.find(3).destroy # find, then destroy
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| Article.destroy(3) # same thing
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| Article.delete(3) # delete directly from database with no object callbacks
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| Article.delete_all("published_at < '2011-01-01'") # conditional
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| </source>
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|
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| === Validation and Errors ===
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| <source lang="ruby">
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| class Article< ActiveRecord::Base
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| validates :title, :presence => true
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| validates :body, :presence => true
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| end
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| </source>
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|
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| <source lang="ruby">
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| article = Article.new
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| article.errors.any? # false
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| article.save # returns false because of validation
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| article.errors.full_messages # ["Title can't be blank", "Body can't be blank"]
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| article.errors.on(:title) # "can't be blank"
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| article.valid? # false
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| </source>
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|
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| === Associations ===
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| ==== One-to-one ====
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| <source lang="ruby">
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| class User < ActiveRecord::Base
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| has_one :profile # assumes User.profile_id column
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| end # creates User.profile method
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| -------------------------------
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| class Profile < ActiveRecord::Base
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| belongs_to :user # assumes Profile.user_id column
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| end # creates Profile.user method
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| </source>
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|
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|
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| ==== One-to-many ====
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| <source lang="ruby">
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| class Message < ActiveRecord::Base
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| has_many :attachments # creates Message.attachments method
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| end
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| -------------------------------
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| class Attachment < ActiveRecord::Base
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| belongs_to :message # assumes Attachment.message_id column
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| end # creates Attachment.message method
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| </source>
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