diff options
| -rw-r--r-- | activerecord/lib/active_record/associations/collection_association.rb | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb index 24718cd4b1..7ee942d153 100644 --- a/activerecord/lib/active_record/associations/collection_association.rb +++ b/activerecord/lib/active_record/associations/collection_association.rb @@ -298,9 +298,38 @@ module ActiveRecord load_target.size end - # Equivalent to <tt>collection.size.zero?</tt>. If the collection has - # not been already loaded and you are going to fetch the records anyway - # it is better to check <tt>collection.length.zero?</tt>. + # Returns true if the collection is empty. Equivalent to + # <tt>collection.size.zero?</tt>. If the collection has not been already + # loaded and you are going to fetch the records anyway it is better to + # check <tt>collection.length.zero?</tt>. + # + # class Person < ActiveRecord::Base + # has_many :pets + # end + # + # person.pets.count # => 1 + # person.pets.empty? # => false + # + # person.pets.delete_all + # person.pets.count # => 0 + # person.pets.empty? # => true + # + # Also, you can pass a block to define a criteria. The behaviour + # is the same, it returns true if the collection based on the + # criteria is empty. + # + # person.pets + # # => [#<Pet name: "Wy", group: "cats">] + # + # person.pets.empty? do |pet| + # pet.group == 'cats' + # end + # # => false + # + # person.pets.empty? do |pet| + # pet.group == 'dogs' + # end + # # => true def empty? size.zero? end |