Rake 中的“环境”任务是什么？

Question

According to " Custom Rake Tasks ":

desc "Pick a random user as the winner"
task :winner => :environment do
  puts "Winner: #{pick(User).name}"
end

As far as I know, the :winner =>:environment means "do environment before winner ". But what's environment ? When should I use it?

I tried rake -T , but in the list I couldn't find environment .

Answer 1

You can get access to your models, and in fact, your whole environment by making tasks dependent on the environment task. This lets you do things like run rake RAILS_ENV=staging db:migrate .

See " Custom Rake Tasks ".

Answer 2

It loads in your Rails environment so you can actually use your models and what not. Otherwise, it has no idea about those things.

So if you made a task that just did puts "HI!" then you don't need to add the :environment task to the dependencies. But if you wish to do something like User.find(1) well that will need it.

Answer 3

Including =>:environment will tell Rake to load full the application environment, giving the relevant task access to things like classes, helpers, etc. Without the :environment , you won't have access to any of those extras.

Also =>:environment itself does not make available any environment-related variables, eg environment , @environment , RAILS_ENV , etc.