How do I return early from a rake task?
RubyRakeRuby Problem Overview
I have a rake task where I do some checks at the beginning, if one of the checks fails I would like to return early from the rake task, I don't want to execute any of the remaining code.
I thought the solution would be to place a return where I wanted to return from the code but I get the following error
unexpected return
Ruby Solutions
Solution 1 - Ruby
A Rake task is basically a block. A block, except lambdas, doesn't support return but you can skip to the next statement using next which in a rake task has the same effect of using return in a method.
task :foo do
puts "printed"
next
puts "never printed"
end
Or you can move the code in a method and use return in the method.
task :foo do
do_something
end
def do_something
puts "startd"
return
puts "end"
end
I prefer the second choice.
Solution 2 - Ruby
You can use abort(message) from inside the task to abort that task with a message.
Solution 3 - Ruby
Return with an Error ❌
If you're returning with an error (i.e. an exit code of 1) you'll want to use abort, which also takes an optional string param that will get outputted on exit:
task :check do
# If any of your checks fail, you can exit early like this.
abort( "One of the checks has failed!" ) if check_failed?
end
On the command line:
$ rake check && echo "All good"
#=> One of the checks has failed!
Return with Success ✅
If you're returning without an error (i.e. an exit code of 0) you'll want to use exit, which does not take a string param.
task :check do
# If any of your checks fail, you can exit early like this.
exit if check_failed?
end
On the command line:
$ rake check && echo "All good"
#=> All good
This is important if you're using this in a cron job or something that needs to do something afterwards based on whether the rake task was successful or not.
Bonus: Return with an Error from a rescue block without the stacktrace.
By default, if you use abort inside of a rescue block, it will output the entire stack trace, even if you just use abort without re-raising the error.
To get around this, you can supply a non-zero exit code to the exit command, like:
task :check do
begin
do_the_thing_that_raises_an_exception
rescue => error
puts error.message
exit( 1 )
end
end
Solution 4 - Ruby
I tend to use abort which is a better alternative in such situations, for example:
task :foo do
something = false
abort 'Failed to proceed' unless something
end
Solution 5 - Ruby
If you need to break out of multiple block levels, you can use fail.
For example
task :something do
[1,2,3].each do |i|
...
fail "some error" if ...
end
end
Solution 6 - Ruby
If you meant exiting from a rake task without causing the "rake aborted!" message to be printed, then you can use either "abort" or "exit". But "abort", when used in a rescue block, terminates the task as well as prints the whole error (even without using --trace). So "exit" is what I use.
Solution 7 - Ruby
I used next approach suggested by Simone Carletti, since when testing rake task, abort, which in fact is just a wrapper for exit, is not the desired behavior.
Example:
task auto_invoice: :environment do
if Application.feature_disabled?(:auto_invoice)
$stderr.puts 'Feature is disabled, aborting.'
next
end