Rails 3 - Revision history

Scott: Blanked the page

2011-06-28T21:02:14Z

Blanked the page

← Older revision		Revision as of 21:02, 28 June 2011
Line 1:		Line 1:

	~~== Active Record ==~~

	~~=== Create and Save ===~~

	~~<source lang="ruby">~~
	~~article = Article.new # make an empty object~~
	~~article.title = "My Title" # add attributes~~
	~~article.author = "Herman"~~
	~~article.save # save to database~~
	~~</source>~~

	~~<source lang="ruby">~~
	~~article.create(:title => "My Title", :author => "Herman") # make, set attributes, and save~~
	~~</source>~~

	~~<source lang="ruby">~~
	~~article.new_record? # new means not saved to database~~
	~~</source>~~

	~~=== Find ===~~
	~~<source lang="ruby">~~
	~~Article.find(3) # look for id = 3~~
	~~Article.first # same as Article.find(:first), uses "LIMIT 1" in SQL, so may not be id = 1~~
	~~Article.last # same as Article.find(:last)~~
	~~Article.all # same as Article.find(:all)~~
	~~Article.where(:title => 'RailsConf').first # chaining~~
	~~Article.find_by_title('RailsConf') # dynamic finder~~
	~~</source>~~

	~~=== Update ===~~
	~~<source lang="ruby">~~
	~~article = Article.first~~
	~~article.title = "Rails 3 is great"~~
	~~article.published_at = Time.now~~
	~~article.save~~
	~~</source>~~
	~~<source lang="ruby">~~
	~~article = Article.first~~
	~~article.update_attributes(:title => "RailsConf2010", :published_at => 1.day.ago) # saves too~~
	~~</source>~~

	~~=== Delete ===~~
	~~<source lang="ruby">~~
	~~Article.find(3).destroy # find, then destroy~~
	~~Article.destroy(3) # same thing~~
	~~Article.delete(3) # delete directly from database with no object callbacks~~
	~~Article.delete_all("published_at < '2011-01-01'") # conditional~~
	~~</source>~~

	~~=== Validation and Errors ===~~
	~~<source lang="ruby">~~
	~~class Article< ActiveRecord::Base~~
	~~validates :title, :presence => true~~
	~~validates :body, :presence => true~~
	~~end~~
	~~</source>~~

	~~<source lang="ruby">~~
	~~article = Article.new~~
	~~article.errors.any? # false~~
	~~article.save # returns false because of validation~~
	~~article.errors.full_messages # ["Title can't be blank", "Body can't be blank"]~~
	~~article.errors.on(:title) # "can't be blank"~~
	~~article.valid? # false~~
	~~</source>~~

	~~=== Associations ===~~
	~~==== One-to-one ====~~
	~~<source lang="ruby">~~
	~~class User < ActiveRecord::Base~~
	~~has_one :profile # assumes User.profile_id column~~
	~~end # creates User.profile method~~
	~~-------------------------------~~
	~~class Profile < ActiveRecord::Base~~
	~~belongs_to :user # assumes Profile.user_id column~~
	~~end # creates Profile.user method~~
	~~</source>~~


	~~==== One-to-many ====~~
	~~<source lang="ruby">~~
	~~class Message < ActiveRecord::Base~~
	~~has_many :attachments # creates Message.attachments method~~
	~~end~~
	~~-------------------------------~~
	~~class Attachment < ActiveRecord::Base~~
	~~belongs_to :message # assumes Attachment.message_id column~~
	~~end # creates Attachment.message method~~
	~~</source>~~

Scott at 21:01, 28 June 2011

2011-06-28T21:01:27Z

← Older revision		Revision as of 21:01, 28 June 2011
Line 1:		Line 1:
	~~== Application Setup ==~~
	* create project with
	~~<pre>~~
	~~rails new my_project~~
	~~rails -d mysql new my_project # if you don't want the default sqlite3~~
	~~</pre>~~
	* add gem dependencies to <code>Gemfile</code> at the root level
	* update <code>config/application.rb</code> to load needed dependencies and update defaults
	* double-check <code>/config/initializers</code> and <code>/config/environments</code>
	* edit <code>config/database.yml</code> to connect to your database

	~~=== Notes ===~~
	~~Files in <code>lib/</code> are not automatically loaded, so you need to <code>require</code> them.~~

	~~In <code>config/environments/development.rb</code>, set~~
	~~<pre>~~
	~~config.action_mailer.perform_deliveries = false~~
	~~</pre>~~
	~~No delivery attempt is performed, but you can still see the mail in the log file to check it looks good~~

	~~== Database Setup ==~~
	* create database with
	~~<pre>~~
	~~rake db:create~~
	~~</pre>~~

	~~=== Create a table and its controller ===~~
	~~<pre>~~
	~~rails generate model Article~~
	~~</pre>~~
	~~Edit <code>db/migrate/20100223220648_create_articles.rb</code> to look like this:~~
	~~<source lang="ruby">~~
	~~class CreateArticles < ActiveRecord::Migration~~
	~~def self.up~~
	~~create_table :articles do \|t\|~~
	~~t.string :title~~
	~~t.text :body~~
	~~t.datetime :published_at~~
	~~t.timestamps~~
	~~end~~
	~~end~~
	~~def self.down~~
	~~drop_table :articles~~
	~~end~~
	~~end~~
	~~</source>~~
	~~To create/update the table:~~
	~~<pre>~~
	~~rake db:migrate~~
	~~</pre>~~
	~~To generate the controller:~~
	~~<pre>~~
	~~rails generate controller articles~~
	~~</pre>~~

	~~=== Make a scaffold ===~~
	~~To make a scaffold for the table to allow easy create/update/delete in development:~~
	~~<pre>~~
	~~rails generate scaffold Article title:string body:text published_at:datetime --skip-migration~~
	~~</pre>~~
	~~WARNING: As you develop your application, you will eventually replace most or even all of the code that the scaffold generates in the controller.~~

	~~=== Update table and scaffold ===~~
	~~To modify the table, generate a custom migration:~~
	~~<pre>~~
	~~rails generate migration add_excerpt_and_location_to_articles excerpt:string location:string~~
	~~</pre>~~
	~~creates this migration file <code>db/migrate/20100223232337_add_excerpt_and_location_to_articles.rb</code>:~~
	~~<source lang="ruby">~~
	~~class AddExcerptAndLocationToArticles < ActiveRecord::Migration~~
	~~def self.up~~
	~~add_column :articles, :excerpt, :string~~
	~~add_column :articles, :location, :string~~
	~~end~~
	~~def self.down~~
	~~remove_column :articles,~~
	~~:excerpt remove_column :articles, :location~~
	~~end~~
	~~end~~
	~~</source>~~
	~~Run <code>rake db:migrate</code> again to update the database.~~

	~~Now update the scaffold:~~
	~~<pre>~~
	~~rails generate scaffold Article title:string location:string excerpt:string body:text published_at:datetime --skip-migration~~
	~~</pre>~~

	~~=== Add validations to the model ===~~
	~~Edit <code>app/models/article.rb</code>:~~
	~~<source lang="ruby">~~
	~~class Article < ActiveRecord::Base~~
	~~validates :title, :presence => true~~
	~~validates :body, :presence => true~~
	~~end~~
	~~</source>~~

	~~== Other rails commands ==~~
	~~<pre>~~
	~~rails console~~
	~~rails dbconsole~~
	~~rails server~~
	~~rails runner~~
	~~</pre>~~

	~~== Routing ==~~
	~~Configured in <code>config/routes.rb</code>~~
	~~<pre>~~
	~~match 'products/:id' => 'products#show'~~
	~~</pre>~~
	~~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~~

	~~To create a link to this route (old way):~~
	~~<pre>~~
	~~link_to "Products", :controller => "products", :action => "show", :id => 1~~
	~~</pre>~~

	~~To restrict the HTTP method, use get or post instead of match:~~
	~~<pre>~~
	~~get 'products/:id' => 'products#show'~~
	~~</pre>~~

	~~To redirect:~~
	~~<pre>~~
	~~match "/foo", :to => redirect("/bar")~~
	~~</pre>~~

	~~== Logging ==~~
	~~Use these in models, views, controllers to send timestamped messages to the log.~~
	~~<source lang="ruby">~~
	~~logger.debug "debug message"~~
	~~logger.info "info message"~~
	~~logger.warn "something bad"~~
	~~logger.error "something broke"~~
	~~logger.fatal "application dead"~~
	~~</source>~~

	== Active Record ==		== Active Record ==

Scott: /* One-to-many */

2011-06-28T20:39:11Z

One-to-many

← Older revision		Revision as of 20:39, 28 June 2011
Line 217:		Line 217:
	<source lang="ruby">		<source lang="ruby">
	class Message < ActiveRecord::Base		class Message < ActiveRecord::Base
	has_many :attachments # creates Message.attachments method		has_many :attachments # creates Message.attachments method
	end		end
	-------------------------------		-------------------------------
	class Attachment < ActiveRecord::Base		class Attachment < ActiveRecord::Base
	belongs_to :message # assumes Attachment.message_id column		belongs_to :message # assumes Attachment.message_id column
	end		end # creates Attachment.message method
	</source>		</source>

Scott: /* Associations */

2011-06-28T20:37:19Z

Associations

← Older revision		Revision as of 20:37, 28 June 2011
Line 202:		Line 202:

	=== Associations ===		=== Associations ===
			==== One-to-one ====
			<source lang="ruby">
			class User < ActiveRecord::Base
			has_one :profile # assumes User.profile_id column
			end # creates User.profile method
			-------------------------------
			class Profile < ActiveRecord::Base
			belongs_to :user # assumes Profile.user_id column
			end # creates Profile.user method
			</source>


			==== One-to-many ====
	<source lang="ruby">		<source lang="ruby">
	class Message < ActiveRecord::Base		class Message < ActiveRecord::Base
	has_many :attachments		has_many :attachments # creates Message.attachments method
	end		end
	~~</source>~~		-------------------------------
	~~<source lang="ruby">~~
	class Attachment < ActiveRecord::Base		class Attachment < ActiveRecord::Base
	belongs_to :message		belongs_to :message # assumes Attachment.message_id column
	end		end
	</source>		</source>

Scott: /* Validation and Errors */

2011-06-28T20:20:48Z

Validation and Errors

@@ Line 199: / Line 199: @@
 article.errors.on(:title)     # "can't be blank"
 article.valid?                # false
 </source>

Scott: /* Update */

2011-06-28T20:06:09Z

Update

← Older revision		Revision as of 20:06, 28 June 2011
Line 173:		Line 173:
	<source lang="ruby">		<source lang="ruby">
	article = Article.first		article = Article.first
	article.update_attributes(:title => "RailsConf2010", :published_at => 1.day.ago)		article.update_attributes(:title => "RailsConf2010", :published_at => 1.day.ago) # saves too
	</source>		</source>

Scott: /* Delete */

2011-06-28T18:44:06Z

Delete

@@ Line 182: / Line 182: @@
 Article.delete(3)        # delete directly from database with no object callbacks
 Article.delete_all("published_at < '2011-01-01'")  # conditional
 </source>

Scott: /* Logging */

2011-06-28T18:36:26Z

Logging

← Older revision		Revision as of 18:36, 28 June 2011
Line 127:		Line 127:
	== Logging ==		== Logging ==
	Use these in models, views, controllers to send timestamped messages to the log.		Use these in models, views, controllers to send timestamped messages to the log.
	<~~pre~~>		<source lang="ruby">
	logger.debug "debug message"		logger.debug "debug message"
	logger.info "info message"		logger.info "info message"
Line 133:		Line 133:
	logger.error "something broke"		logger.error "something broke"
	logger.fatal "application dead"		logger.fatal "application dead"
	</~~pre~~>		</source>

	== Active Record ==		== Active Record ==

Scott: /* Add validations to the model */

2011-06-28T18:36:06Z

Add validations to the model

← Older revision		Revision as of 18:36, 28 June 2011
Line 88:		Line 88:
	=== Add validations to the model ===		=== Add validations to the model ===
	Edit <code>app/models/article.rb</code>:		Edit <code>app/models/article.rb</code>:
	<~~pre~~>		<source lang="ruby">
	class Article < ActiveRecord::Base		class Article < ActiveRecord::Base
	validates :title, :presence => true		validates :title, :presence => true
	validates :body, :presence => true		validates :body, :presence => true
	end		end
	</~~pre~~>		</source>

	== Other rails commands ==		== Other rails commands ==

Scott: /* Update table and scaffold */

2011-06-28T18:35:47Z

Update table and scaffold

← Older revision		Revision as of 18:35, 28 June 2011
Line 67:		Line 67:
	</pre>		</pre>
	creates this migration file <code>db/migrate/20100223232337_add_excerpt_and_location_to_articles.rb</code>:		creates this migration file <code>db/migrate/20100223232337_add_excerpt_and_location_to_articles.rb</code>:
	<~~pre~~>		<source lang="ruby">
	class AddExcerptAndLocationToArticles < ActiveRecord::Migration		class AddExcerptAndLocationToArticles < ActiveRecord::Migration
	def self.up		def self.up
Line 78:		Line 78:
	end		end
	end		end
	</~~pre~~>		</source>
	Run <code>rake db:migrate</code> again to update the database.		Run <code>rake db:migrate</code> again to update the database.