#400 What's New in Rails 4

Jan 04, 2013 | 20 minutes | Rails 4.0

Rails 4.0 is still unfinished, but it is shaping up to become a great release. Here I show how to setup a new Rails 4.0 (edge) application and walk through many of its new features.

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Fabian Becker almost 12 years ago

If you'd like to read more about Turbolinks check http://geekmonkey.org/articles/28-introducing-turbolinks-for-rails-4-0

Pierre GD almost 7 years ago

Thanks Fabian

Kequc almost 12 years ago

Hi Ryan! Do you feel that there is any discernable cost to getting started writing a new Rails 4 application now and updating it as opposed to waiting for the release? My concerns wouldn't involve many gems. I'm thinking more along the lines of application structure, features getting dropped, or things like that.

Justin Reid almost 12 years ago

You make the changes in big releases easy to understand, thanks!

What I don't quite understand is the move of protected attributes from the model to the controller:

Doesn't that assume you're only going to be using one controller to update a give type of model, else you'll have to repeat your code (like in an admin controller)?
Wouldn't this change make controllers fatter and models skinnier (the opposite direction we push for)?

There's probably something I'm missing, so if someone could enlighten me then I'd be grateful.

Justin Reid almost 12 years ago

Makes more sense after reading this:
http://rubysource.com/rails-4-quick-look-strong-parameters/

Some of repetition that I fear when I see code like this:

def book_params if current_user && current_user.admin? params[:book].permit(:name, :author, :public) else params[:book].permit(:name, :author) end end

Can be reduced be creating constant (named by role?) within the class:

def book_params
if current_user && current_user.admin?
params[:book].permit(User.attrbutes_assignable_by_admin)
else
params[:book].permit(User.attrbutes_assignable_by_non_admin)
end
end
`

And though I understand that this a better placement of state logic, still seems a bit cumbersome.

The whitelist lets me say all the attributes that are permitted unless a specific role was in use. It isn't often, but when it is, it's explicit. This forces me to specify the user role every place I'm acting on an attribute via a controller. And with the increase in times I have to remember to do something the more times I'm likely to miss something an create a security hole.

Again, I'm happy to be enlightened.

Ryan almost 12 years ago

Ryan covered this in episode 371: Strong Parameters

Daniel Bruns almost 12 years ago

I tried following along but I'm having problems with hstore. I've upgraded to the latest version of postgres with homebrew, but rake db:migrate complains about hstore not being a valid type...

Daniel Bruns almost 12 years ago

PG::Error: ERROR: type "hstore" does not exist is the exact error.

Brian Goff almost 12 years ago

You must 'CREATE EXTENSION hstore' first

agence-Web-Guadeloupe over 7 years ago

Hum ... Useful, I've made the same mistake ;-)

Alain Ravet over 11 years ago

see :
- http://stackoverflow.com/questions/12540865/error-with-rails-test-database-using-postgres-using-hstore
- http://blog.remarkablelabs.com/2012/12/a-love-affair-with-postgresql-rails-4-countdown-to-2013

Nebojsa Zoric about 11 years ago

If none of the solutions doesn't work. You can do a 'fix' by adding
'CREATE EXTENSION hstore'
in schema.rb file before any table is created and after running migrations.

After that you can call rake db:test:prepare and it will work.
Later you can just discard changes from schema.rb file.

Sergey Kuleshov almost 12 years ago

Thank you Ryan, I am very excited about Rails 4 and can't wait for it to hit at least pre release.

With all these changes under the hood do you expect it to be tough switching from Rails 3? Or the transitions this time should be smoother than from Rails 2.x to 3.x?

Brian Goff almost 12 years ago

I've messed with both.
It should be a fairly simple transition, assuming you aren't using things that have been deprecated in Rails 3 (which would be removed in Rails 4)... and of course assuming you are at least on Rails 3.1. The Asset Pipeline is a fairly large hurdle.

Esteban Pastorino almost 12 years ago

It should be fairly simple. Most of the new stuff could be used in Rails 3.2 as gems.

I describe the process on this article: http://rubysource.com/get-your-app-ready-for-rails-4/

efries almost 12 years ago

thanks Ryan!
i will learn ember.js :)

btw, anyone having this?

$ rake db:test:prepare

rake aborted!
PG::Error: ERROR: type "hstore" does not exist
LINE 1: ...te, "tags" character varying(255)[], "properties" hstore, "c...

efries almost 12 years ago

config.active_record.schema_format = :sql

helped to run minitest with hstore

Daniel Bruns almost 12 years ago

I get that from simply doing an rake db:migrate on development with an hstore type :(

Bjarki Gudlaugsson almost 12 years ago

I had the same problem and the solution is basically that you have to enable hstore on the database. Run the following (after you have created the db of course :)

$> psql blog_development

blog_development=# CREATE EXTENSION hstore;

For futher information and how to do this as a rails migration see this

Daniel Bruns almost 12 years ago

Yeah, I've figured that out, but it would be nice to know why Ryan didn't have to do that. Is there a better way?

Florent Monbillard almost 12 years ago

Ryan did that command in the migration file:
https://github.com/railscasts/400-what-s-new-in-rails-4/blob/master/blog-after/db/migrate/20130104011551_create_articles.rb#L3

efries almost 12 years ago

also just do a migration for hstore:

def self.up
execute "CREATE EXTENSION hstore"
end

def self.down
execute "DROP EXTENSION hstore"
end
end

Thibaut Assus almost 12 years ago

Amazing episode Ryan, as always !

And I love your last words about others skills than programming ! I personally want to make music in 2013 :)

If you are interested in listening to my music, check out https://soundcloud.com/thibaut-assus-1 :)

I would be also amazed that you could come Ryan to Paris.rb ! I have a couch and I can show you some amazing places in of Paris ! => http://meetup.rubyparis.org/

Happy new year, and stay how you are, amazing and so helpful !

ptantiku almost 12 years ago

For security concerns, is there any possible way to disable the route-showing feature and /rails/info feature?

Ernest Surudo almost 12 years ago

Those will only work in development environment, so there's no need to worry about that in production.

David James almost 12 years ago

Ryan uses the rails executable in the episode. It is important to mention that depending on your setup, that probably will call your 3.2.X install of rails. While Rails is in beta and there is no prerelease gem, you need to use bin/rails:

$ rails -v
Rails 3.2.11

$ bin/rails -v
Rails 4.0.0.beta

This bit me when I found that rails s did not start the server.

tylergannon almost 12 years ago

If you're using the haml-rails gem, for the moment you may get an error running generators, something like:

(erb):19:in template': undefined methodkey_value' for #Haml::Generators::ScaffoldGenerator:0x007fb9712be1e8 (NoMethodError)

This error is fixed by a recent pull request.

Update your Gemfile to use the master branch for the moment...

          ruby
        
gem 'haml-rails', git: 'https://github.com/indirect/haml-rails'

Robert Kolle over 11 years ago

Congrats. 400 Episodes and still great.

MikeOnRails over 11 years ago

I'm following along but getting some no hstore method erros when I run the migrations

rails g scaffold article name content:text published_on:date tags properties:hstore

and in the migration does this

execute "create extension hstore"
create_table :articles do |t|
t.string :name
t.text :content
t.date :published_on
t.string :tags, array: true
t.hstore :properties
t.timestamps
end

However, when I ran this migration I got an undefined method 'hstore' error. I then went into my test database and created the hstore extension as you see below (rather than in the migration file as Ryan did)

psql rails4test2_development
psql (9.2.3)
Type "help" for help.

rails4test2_development=# CREATE EXTENSION hstore;

But I got the same error when I ran the migration.

undefined method hstore' for #<ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::TableDefinition:0x007fa7ee7a9138>/Users/me/Sites/rails4test2/db/migrate/20130511204911_create_articles.rb:9:inblock in change'
/Users/me/Sites/rails4test2/db/migrate/20130511204911_create_articles.rb:4:in `change'

Can anyone help me understand why this isn't working for me?

Bogdan Kulbida over 11 years ago

Hi Ryan! Thanks for the challenge! It sounds really cool :) +1

arta over 11 years ago

Ryan, you are an outstanding teacher. 1000+1 thanks for your railscasts.

sandy over 11 years ago

Hi great tutorial .. but have a problem with checkboxes nothing append when i'am updating??
some body has the same probleme?

Clinton Cecil about 11 years ago

Not sure if you figured it out, but just ran into the same problem.

in the strong_params method, you must make tags an array

          ruby
        
def article_params
  params.require(:article).permit(:name, :content, :published_at, tags: [])
end

SimonToivoTelhaug about 10 years ago

Hey
$ ruby -v
ruby 2.0.0p481

$ rails -v

Rails 4.1.5

I got some problem with

          ruby
        
params.require(:article).permit(:name, :content, :published_on, :tags, :properties)

When I tryed to do a update, It leaved :tags out. It is becaus it expect a sting, not a array

This is the fix

          ruby
        
params.require(:article).permit(:name, :content, :published_on, :properties, tags: [])

Shubham Gupta over 11 years ago

Ryan, pretty nice screencast as always. However, the migration is incorrect. It is irreversible due to the execute statement present. So, it can not be 'rake db:rollback'ed !! Specific up / down methods could be used here instead.

Jim Cushing about 11 years ago

Ryan,

It appears this screencast is no longer playing. In Chrome, it says "Can't play video. Media source loading has failed." It won't play in Safari, either, though no error is displayed.

I'm not having trouble with any of the other screencasts, just this one.