@questions=Question.left_outer_joins(:likes).group('questions.id').select('questions.*, COUNT(likes.*) AS likes_count').distinct.reorder(likes_count: :desc).limit(100)
class Klass
VALUE = "I'm VALUE"
@@class_val = "I'm class_val"
end
class A < Klass
end
class B < A
def self.display_bal
puts @@class_val
end
end
# スーパークラスの定数の参照
puts B::VALUE
# => I'm VALUE
# クラス変数の継承
B.display_val
# => I'm class_val
class Klass
# Klass
p self
# Klass
def (p self).class_method
puts "inner_class_method"
# Klass
p self
end
def instance_method
puts "inner_instance_method"
# <Klass:0x00007fa07e1a47c8>
p self
end
end
Klass.class_method
klass_instanse = Klass.new
klass_instanse.instance_method
VALUE = "Top level"
class TopKlass
VALUE = "in TopKlass"
class InnerKlass
def self.put_value
puts VALUE
end
end
end
TopKlass::InnerKlass.put_value
# => in TopKlass
VALUE = "Top level"
class TopKlass
VALUE = "in TopKlass"
end
class TopKlass::InnerKlass
def self.put_value
puts VALUE
end
end
TopKlass::InnerKlass.put_value
# => Top level
defself.find(*args)ifargs.first&&args.first.is_a?(String)&&!args.first.match(/^\d*$/)project=find_by_identifier(*args)raiseActiveRecord::RecordNotFound,"Couldn't find Project with identifier=#{args.first}"ifproject.nil?projectelsesuperendend
defself.find(*args)ifargs.first&&args.first.is_a?(String)&&!args.first.match(/^\d*$/)project=find_by_identifier(*args)raiseActiveRecord::RecordNotFound,"Couldn't find Project with identifier=#{args.first}"ifproject.nil?projectelsesuperendend
== 20201011010946 CreatePosts: migrating ======================================
-- create_table(:posts)
rails aborted!
StandardError: An error has occurred, this and all later migrations canceled:
PG::DuplicateTable: ERROR: relation "posts" already exists
(つづく）
