For ad hoc Rails tasks we have a few implementation alternatives, chief among which would seem to be:
script/runner some_useful_thing
and:
rake some:other_useful_thing
Which option should I prefer? If there's a clear favourite then when, if ever, should I consider using the other? If never, then why would you suppose it's still present in the framework without deprecation warnings?
The difference between them is that script/runner boots Rails whereas a Rake task doesn't unless you tell it to by making the task depend on :environment, like this:
task :some_useful_task => :environment do
# do some useful task
end
Since booting Rails is expensive, it might be worth skipping if you can avoid it.
Other than that, they are roughly equivalent. I use both, but lately I've used script/runner executing a script separately more.
Passing parameters to a rake task is a pain in the butt, to say the least. You either need to resort to environment variables or a very hackish parameter system that is not intuitive and has lots of caveats.
If your task needs to handle command line arguments gracefully then writing a script is the way to go.
Luke Francl mentions script/runner booting up Rails. That's true. But if you don't want to boot up rails then just run the script as is without script/runner. So the only real difference between scripts and rake tasks are their aesthetics. Choose whatever feels right to you.
I use rake tasks for little tasks (one or two lines). Anything more complicated goes into the script/ directory. I'll break this rule if I think other developers will expect the code to live in one place over another.
FWIW there seems to be some movement away from using script runner in favor of rake:
Update (4/25/2009): I recommend using rake tasks as opposed to script/runner for recurring tasks.
Also, as per this post you can use rake for recurring tasks just fine:
If I then wanted this to run nightly on my production database at midnight, I might write a cronjob that looks something like this:
0 0 * * * cd /var/www/apps/rails_app/ && /usr/local/bin/rake RAILS_ENV=production utils:send_expire_soon_emails
Corrected based on comment 2 down. Give them the karma!
FWIW - Rails 3.0+ changes how you initialize the Rails system in a standalone script.
require File.dirname(__FILE__) + '/config/environment'
As mentioned above you can also do:
rails runner script/<script name>
Or put all the code in a Rake task, but I have a lot of legacy code from Rails 2; so I didn't want to go down that path immediately.
Each has its advantages and disadvantages.
One thing I've done is just write normal ruby scripts and put them in the script/maintenance directory.
All you need to do to load rails and get access to all your models, etc, is put require '../../config/environment.rb' at the top of your file, then you're away.
In Rails 3.0+, the config/environment.rb requires the config/application.rb, that requires the config/boot.rb.
So, to load an app in Rails 3, you still only have to require the environment.rb
For one off commands script/runner can be fine. For anything repeated, a rake task is easier in the long-run, and has a summary if you forget what it does.
I got the impression script/runner was primarily for periodic tasks. E.g., a cron job that runs:
SomeClass.update_from_web('http://www.sourcefordata.gov/')
