Active Record Introduction - 3

ACTIVERECORD Rails 3Sunday, November 13, 11

MVCSunday, November 13, 11

MODEL CLASS in app/models/person.rb class Message < ActiveRecord::Base endSunday, November 13, 11

EVERY MODEL HAS A CORRESPONDING DATABASE TABLESunday, November 13, 11

MVCSunday, November 13, 11

HOW DID WE GET A DATABASE TABLE?Sunday, November 13, 11

RUBY-DRIVEN SCHEMA • scaffold generates db/migrate/20110131021702_create_people.rb • rake db:migrate runs the migration, creates the table •Sunday, November 13, 11

DEMOSunday, November 13, 11

$ rails new ar_exSunday, November 13, 11

$ rails -vSunday, November 13, 11

Edit GemﬁleSunday, November 13, 11

source http://rubygems.org gem ‘rails’ gem ‘rspec-rails’ gem ‘sqlite3’Sunday, November 13, 11

$ bundleSunday, November 13, 11

$ rails g rspec:installSunday, November 13, 11

$ rails g model Message body:text public_key:textSunday, November 13, 11

invoke rspecSunday, November 13, 11

create spec/models/ message_spec.rbSunday, November 13, 11

require spec_helper describe Message do pending "a class in itself" endSunday, November 13, 11

invoke active_recordSunday, November 13, 11

create db/migrate/ 20110208201036_create_messages.rbSunday, November 13, 11

class CreateMessages < ActiveRecord::Migration def self.change # rake db:migrate end def self.up # rake db:migrate end def self.down # rake db:migrate:down VERSION=ﬁle_name # rake db:migrate:redo VERSION=ﬁle_name end endSunday, November 13, 11

create_table :messages do |t| t.text :body t.text :public_key t.timestamps end rails g model Message body:text public_key:textSunday, November 13, 11

drop_table :messagesSunday, November 13, 11

http://apidock.com/rails/ActiveRecord/ ConnectionAdapters/SchemaStatementsSunday, November 13, 11

create app/models/message.rbSunday, November 13, 11

class Message < ActiveRecord::Base endSunday, November 13, 11

Where are the methods?Sunday, November 13, 11

$ rails consoleSunday, November 13, 11

> Message.newSunday, November 13, 11

ActiveRecord::StatementInvalid: Could not ﬁnd table messages from /Users/o_o/.rvm/gems/ruby-1.9.2-p0@rails3/ gems/activerecord-3.0.3/lib/active_record/ connection_adapters/sqlite_adapter.rb:295:in `table_structureSunday, November 13, 11

every model has a corresponding database tableSunday, November 13, 11

$ rails dbSunday, November 13, 11

PRAGMA table_info(messages);Sunday, November 13, 11

nothing!Sunday, November 13, 11

.quit;Sunday, November 13, 11

$ rake db:migrateSunday, November 13, 11

$ rails dbSunday, November 13, 11

PRAGMA table_info(messages);Sunday, November 13, 11

0|id|INTEGER|1||1 1|body|text|0||0 2|public_key|text|0||0 3|created_at|datetime|0||0 4|updated_at|datetime|0||0Sunday, November 13, 11

.quitSunday, November 13, 11

> Message.newSunday, November 13, 11

=> #<Message id: nil, body: nil, public_key: nil, created_at: nil, updated_at: nil>Sunday, November 13, 11

>msg = Message.new >msg.body = 2 >msg.save >msgSunday, November 13, 11

=> #<Message id: 1, body: 2, public_key: nil, created_at: "2011-02-08 20:56:33", updated_at: "2011-02-08 20:56:33">Sunday, November 13, 11

> msg.body.classSunday, November 13, 11

=> FixnumSunday, November 13, 11

> Message.ﬁnd(1)Sunday, November 13, 11

=> #<Message id: 1, body: "2", public_key: nil, created_at: "2011-02-08 20:56:33", updated_at: "2011-02-08 20:56:33">Sunday, November 13, 11

> Message.ﬁnd(1).body.classSunday, November 13, 11

=> StringSunday, November 13, 11

> Message.ﬁnd(1).updated_at.classSunday, November 13, 11

=> ActiveSupport::TimeWithZoneSunday, November 13, 11

One more time..Sunday, November 13, 11

> Message.create!Sunday, November 13, 11

SQL (0.3ms) SELECT name FROM sqlite_master WHERE type = table AND NOT name = sqlite_sequence AREL (0.5ms) INSERT INTO "messages" ("body", "public_key", "created_at", "updated_at") VALUES (NULL, NULL, 2011-02-09 01:55:09.111181, 2011-02-09 01:55:09.111181)Sunday, November 13, 11

> exitSunday, November 13, 11

Active Record FeaturesSunday, November 13, 11

validations http://apidock.com/rails/v3.1.0/ActiveModel/ValidationsSunday, November 13, 11

before_save http://apidock.com/rails/v3.1.0/ActiveRecord/CallbacksSunday, November 13, 11

scopes http://apidock.com/rails/v3.1.0/ActiveRecord/NamedScope/ ClassMethods/scopeSunday, November 13, 11

SQL INJECTIONSunday, November 13, 11

SAFE FROM SQL INJECTION class User < ActiveRecord::Base def self.authenticate_unsafely(user_name, password) find(:first, :conditions => "user_name = #{user_name} AND password = #{password}") end def self.authenticate_safely(user_name, password) find(:first, :conditions => [ "user_name = ? AND password = ?", user_name, password ]) end def self.authenticate_safely_simply(user_name, password) find(:first, :conditions => { :user_name => user_name, :password => password }) endSunday, November 13, 11

QUESTIONS?Sunday, November 13, 11

Active Record Introduction - 3

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