I see both in examples when checking what env one is running in. What's preferred? Are they, for all intents and purposes equal?
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5 Answers
According to the docs, #Rails.env wraps RAILS_ENV:
# File vendor/rails/railties/lib/initializer.rb, line 55
def env
@_env ||= ActiveSupport::StringInquirer.new(RAILS_ENV)
end
But, look at specifically how it's wrapped, using ActiveSupport::StringInquirer:
Wrapping a string in this class gives you a prettier way to test for equality. The value returned by Rails.env is wrapped in a StringInquirer object so instead of calling this:
Rails.env == "production"you can call this:
Rails.env.production?
So they aren't exactly equivalent, but they're fairly close. I haven't used Rails much yet, but I'd say #Rails.env is certainly the more visually attractive option due to using StringInquirer.
5 Comments
brad
nice explanation, thx! I'm also trying to find where RAILS_ENV is defined? Any idea??
Ryan Bigg
It's worth mentioning that
Rails.env is the new standard as RAILS_ENV is being deprecated.
pjammer
Ryan, on a command line, you can't use Rails.env. so if it's deprecating soon, then what would you use on the CLI?
Magne
Using Rails.env.production? secures you against typos actually changing the environment like this: RAILS_ENV = "production". Notice the missed = sign.
Throw Away Account
All this ridiculous complexity just so you can use a question mark?
ENV['RAILS_ENV'] is now deprecated.
You should use Rails.env which is clearly much nicer.
Comments
Before Rails 2.x the preferred way to get the current environment was using the RAILS_ENV constant. Likewise, you can use RAILS_DEFAULT_LOGGER to get the current logger or RAILS_ROOT to get the path to the root folder.
Starting from Rails 2.x, Rails introduced the Rails module with some special methods:
- Rails.root
- Rails.env
- Rails.logger
This isn't just a cosmetic change. The Rails module offers capabilities not available using the standard constants such as StringInquirer support.
There are also some slight differences. Rails.root doesn't return a simple String buth a Path instance.
Anyway, the preferred way is using the Rails module. Constants are deprecated in Rails 3 and will be removed in a future release, perhaps Rails 3.1.
2 Comments
Benjamin Oakes
We're using 2.1.2 on a project.
Rails.env works without a problem.Strange behaviour while debugging my app: require "active_support/notifications" (rdb:1) p ENV['RAILS_ENV'] "test" (rdb:1) p Rails.env "development"
I would say that you should stick to one or another (and preferably Rails.env)
Comments
Update: in Rails 3.0.9: env method defined in railties/lib/rails.rb
