耙子流产了！ 未定义的方法“空”？ 对于nil：NilClass

Question

I have some rake tasks defined and within those tasks; there is a code as follows

task :stale => :environment do |_, args|
    if args.extras.empty?

When I run the task; it gets aborted with the following error

rake aborted! undefined method `empty?' for nil:NilClass /lib/tasks/:387:in `block (3 levels) in ' /vendor/bundle/ruby/2.2.0/gems/bugsnag-2.8.12/lib/bugsnag/rake.rb:12:in `execute_with_bugsnag' Tasks: TOP =>

How could this error be resolved?

Answer 1

NilClass simply does not have a method called empty? and args.extras is obviously nil at the moment.

The best alternative in this case is blank? which will return true if the array/string is empty or if args.extra is nil.

task :stale => :environment do |_, args|
    if args.extras.blank?

Here's a nice table from here showing the differences between empty? , blank? , etc.