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Rails 4.0 by Mind Map: Rails 4.0
5.0 stars - 4 reviews range from 0 to 5

Rails 4.0


BostonRB: what to expect in Rails 4.0

Ruby on Rails Guides: Rails 4.0

Rails 4.0 Whirlwind tour

Rails 4 in 30`

Why should I care about Rails 4 (video)

Rails 4 countdown to 2013

Rails 4: What's new (JangoSteve)

Get your app ready for Rails 4

[ Railscasts ] What's new in Rails 4

[ SD Ruby] What's new in Rails 4

[ EngineYard ] Rails 4, Part 2

[ EngineYard ] Rails 4, Part 1


ActiveRecord is a Ruby library that implements the object-relational mapping (ORM) design pattern. It creates a persistable domain model from business objects and database tables, where logic and data are presented as a unified package. ActiveRecord adds inheritance and associations to the pattern above, solving two substantial limitations of that pattern. A set of macros acts as a domain language for the latter, and the SingleTableInheritance pattern is integrated for the former; thus, ActiveRecord increases the functionality of the active record pattern approach to database interaction. ActiveRecord is the default model component of the Model-view-controller web-application framework Ruby on Rails, and is also a stand-alone ORM package for other Ruby applications. In both forms, it was conceived of by David Heinemeier Hansson, and has been improved upon by a number of contributors.

MySQL strict mode by default


Support for specifying transaction isolation level

Schema cache dump



Associations in Rails 4

'where.not' query method

Add metadata (fingerprint, name) to schema_migrations

Bang versions of relation query methods

ActiveRecord::Base.all returns a Relation instead of an Array.

Add 'find_or_create_by', 'find_or_create_by!' and 'find_or_initialize_by' methods to Relation

Add CollectionProxy#scope

Add support for partial inserts

rename update_attributes to update

What's new in Active Record [ Rails 4 countdown ]

Method '.unscope'

Scope conditions are combined using AND

Transactions can be turned off per migration

'on' and 'off' are type casted into boolean

new migration helper 'create_join_table' for HABTM join tables

added 'Relation#find' and 'Relation#find_by!'

custom index type support


New deprecation policy

Turned into plugins


Deprecations (Rails 4 only)

Updated test names and locations

memcache-client replaced with dalli



Routing concerns


Strong parameters



Rename all action callbacks from *_filer to *_action

Decouple ActionPack and ActionView

HTML5 tag helpers

Support for custom flash types

Collection Form Helpers [ Rails 4 countdown ]

content_for with flush parameter


Threadsafe on by default

PATCH verb instead of PUT

Asynchronous ActionMailer (postponed)

Queue API (postponed)

ActiveModel::Model (removed)

public/index.html is replaced by internal welcome_controller

add app/models/concerns and app/controllers/concerns to the load path

introduce folder ./bin for app's executables

introduce assert_not

Absence validation

config eager loading

AS. Object#try can call only public methods


Default headers

set escaping HTML in json encoding to true by default

Encrypted cookie store