diff options
10 files changed, 86 insertions, 2 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md index a4cf6023e1..be96f9fa2a 100644 --- a/activerecord/CHANGELOG.md +++ b/activerecord/CHANGELOG.md @@ -1,3 +1,7 @@ +* Add ActiveRecord `#second_to_last` and `#third_to_last` methods. + + *Brian Christian* + * Added `numeric` helper into migrations. Example: diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb index 9f2c7292ea..2dca6b612e 100644 --- a/activerecord/lib/active_record/associations/collection_association.rb +++ b/activerecord/lib/active_record/associations/collection_association.rb @@ -136,6 +136,14 @@ module ActiveRecord first_nth_or_last(:forty_two, *args) end + def third_to_last(*args) + first_nth_or_last(:third_to_last, *args) + end + + def second_to_last(*args) + first_nth_or_last(:second_to_last, *args) + end + def last(*args) first_nth_or_last(:last, *args) end diff --git a/activerecord/lib/active_record/associations/collection_proxy.rb b/activerecord/lib/active_record/associations/collection_proxy.rb index fe693cfbb6..2a9627a474 100644 --- a/activerecord/lib/active_record/associations/collection_proxy.rb +++ b/activerecord/lib/active_record/associations/collection_proxy.rb @@ -197,6 +197,16 @@ module ActiveRecord @association.forty_two(*args) end + # Same as #first except returns only the third-to-last record. + def third_to_last(*args) + @association.third_to_last(*args) + end + + # Same as #first except returns only the second-to-last record. + def second_to_last(*args) + @association.second_to_last(*args) + end + # Returns the last record, or the last +n+ records, from the collection. # If the collection is empty, the first form returns +nil+, and the second # form returns an empty array. diff --git a/activerecord/lib/active_record/querying.rb b/activerecord/lib/active_record/querying.rb index 1f429cfd94..5259797223 100644 --- a/activerecord/lib/active_record/querying.rb +++ b/activerecord/lib/active_record/querying.rb @@ -1,7 +1,7 @@ module ActiveRecord module Querying delegate :find, :take, :take!, :first, :first!, :last, :last!, :exists?, :any?, :many?, to: :all - delegate :second, :second!, :third, :third!, :fourth, :fourth!, :fifth, :fifth!, :forty_two, :forty_two!, to: :all + delegate :second, :second!, :third, :third!, :fourth, :fourth!, :fifth, :fifth!, :forty_two, :forty_two!, :third_to_last, :third_to_last!, :second_to_last, :second_to_last!, to: :all delegate :first_or_create, :first_or_create!, :first_or_initialize, to: :all delegate :find_or_create_by, :find_or_create_by!, :find_or_initialize_by, to: :all delegate :find_by, :find_by!, to: :all diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb index d48bcea28a..90a6a466fd 100644 --- a/activerecord/lib/active_record/relation/finder_methods.rb +++ b/activerecord/lib/active_record/relation/finder_methods.rb @@ -242,6 +242,38 @@ module ActiveRecord find_nth! 41 end + # Find the third-to-last record. + # If no order is defined it will order by primary key. + # + # Person.third_to_last # returns the third-to-last object fetched by SELECT * FROM people + # Person.offset(3).third_to_last # returns the third-to-last object from OFFSET 3 + # Person.where(["user_name = :u", { u: user_name }]).third_to_last + def third_to_last + find_nth -3 + end + + # Same as #third_to_last but raises ActiveRecord::RecordNotFound if no record + # is found. + def third_to_last! + find_nth! -3 + end + + # Find the second-to-last record. + # If no order is defined it will order by primary key. + # + # Person.second_to_last # returns the second-to-last object fetched by SELECT * FROM people + # Person.offset(3).second_to_last # returns the second-to-last object from OFFSET 3 + # Person.where(["user_name = :u", { u: user_name }]).second_to_last + def second_to_last + find_nth -2 + end + + # Same as #second_to_last but raises ActiveRecord::RecordNotFound if no record + # is found. + def second_to_last! + find_nth! -2 + end + # Returns true if a record exists in the table that matches the +id+ or # conditions given, or false otherwise. The argument can take six forms: # diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb index ecaa521283..e975f4fbdd 100644 --- a/activerecord/test/cases/associations/has_many_associations_test.rb +++ b/activerecord/test/cases/associations/has_many_associations_test.rb @@ -408,6 +408,16 @@ class HasManyAssociationsTest < ActiveRecord::TestCase end assert_no_queries do + bulbs.third_to_last() + bulbs.third_to_last({}) + end + + assert_no_queries do + bulbs.second_to_last() + bulbs.second_to_last({}) + end + + assert_no_queries do bulbs.last() bulbs.last({}) end diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md index bd333da081..3d4cc8fae6 100644 --- a/activesupport/CHANGELOG.md +++ b/activesupport/CHANGELOG.md @@ -1,3 +1,7 @@ +* Add `Array#second_to_last` and `Array#third_to_last` methods. + + *Brian Christian* + * Fix regression in `Hash#dig` for HashWithIndifferentAccess. *Jon Moss* diff --git a/activesupport/lib/active_support/core_ext/array/access.rb b/activesupport/lib/active_support/core_ext/array/access.rb index 3177d8498e..37d833887a 100644 --- a/activesupport/lib/active_support/core_ext/array/access.rb +++ b/activesupport/lib/active_support/core_ext/array/access.rb @@ -73,4 +73,18 @@ class Array def forty_two self[41] end + + # Equal to <tt>self[-3]</tt>. + # + # %w( a b c d e ).third_to_last # => "c" + def third_to_last + self[-3] + end + + # Equal to <tt>self[-2]</tt>. + # + # %w( a b c d e ).second_to_last # => "d" + def second_to_last + self[-2] + end end diff --git a/activesupport/test/core_ext/array/access_test.rb b/activesupport/test/core_ext/array/access_test.rb index 3f1e0c4cb4..1d834667f0 100644 --- a/activesupport/test/core_ext/array/access_test.rb +++ b/activesupport/test/core_ext/array/access_test.rb @@ -26,6 +26,8 @@ class AccessTest < ActiveSupport::TestCase assert_equal array[3], array.fourth assert_equal array[4], array.fifth assert_equal array[41], array.forty_two + assert_equal array[-3], array.third_to_last + assert_equal array[-2], array.second_to_last end def test_without diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md index 0aca6db9b6..10122629b2 100644 --- a/guides/source/active_support_core_extensions.md +++ b/guides/source/active_support_core_extensions.md @@ -2240,7 +2240,7 @@ Similarly, `from` returns the tail from the element at the passed index to the e [].from(0) # => [] ``` -The methods `second`, `third`, `fourth`, and `fifth` return the corresponding element (`first` is built-in). Thanks to social wisdom and positive constructiveness all around, `forty_two` is also available. +The methods `second`, `third`, `fourth`, and `fifth` return the corresponding element, as do `second_to_last` and `third_to_last` (`first` and `last` are built-in). Thanks to social wisdom and positive constructiveness all around, `forty_two` is also available. ```ruby %w(a b c d).third # => "c" |