diff options
Diffstat (limited to 'activerecord/lib/active_record/relation/finder_methods.rb')
-rw-r--r-- | activerecord/lib/active_record/relation/finder_methods.rb | 77 |
1 files changed, 47 insertions, 30 deletions
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb index 19244bcf95..5d4a045097 100644 --- a/activerecord/lib/active_record/relation/finder_methods.rb +++ b/activerecord/lib/active_record/relation/finder_methods.rb @@ -117,9 +117,9 @@ module ActiveRecord # def first(limit = nil) if limit - find_nth_with_limit(offset_index, limit) + find_nth_with_limit_and_offset(0, limit, offset: offset_index) else - find_nth(0, offset_index) + find_nth 0 end end @@ -145,15 +145,23 @@ module ActiveRecord # # [#<Person id:4>, #<Person id:3>, #<Person id:2>] def last(limit = nil) - if limit - if order_values.empty? && primary_key - order(arel_table[primary_key].desc).limit(limit).reverse - else - to_a.last(limit) - end - else - find_last - end + return find_last(limit) if loaded? + + result = order_values.empty? && primary_key ? order(arel_table[primary_key].desc) : reverse_order + result = result.limit!(limit || 1) + limit ? result.reverse : result.first + rescue ActiveRecord::IrreversibleOrderError + ActiveSupport::Deprecation.warn(<<-WARNING.squish) + Finding a last element by loading the relation when SQL ORDER + can not be reversed is deprecated. + Rails 5.1 will raise ActiveRecord::IrreversibleOrderError in this case. + Please call `to_a.last` if you still want to load the relation. + WARNING + find_last(limit) + end + + def find_last(limit) + limit ? to_a.last(limit) : to_a.last end # Same as #last but raises ActiveRecord::RecordNotFound if no record @@ -169,7 +177,7 @@ module ActiveRecord # Person.offset(3).second # returns the second object from OFFSET 3 (which is OFFSET 4) # Person.where(["user_name = :u", { u: user_name }]).second def second - find_nth(1, offset_index) + find_nth 1 end # Same as #second but raises ActiveRecord::RecordNotFound if no record @@ -185,7 +193,7 @@ module ActiveRecord # Person.offset(3).third # returns the third object from OFFSET 3 (which is OFFSET 5) # Person.where(["user_name = :u", { u: user_name }]).third def third - find_nth(2, offset_index) + find_nth 2 end # Same as #third but raises ActiveRecord::RecordNotFound if no record @@ -201,7 +209,7 @@ module ActiveRecord # Person.offset(3).fourth # returns the fourth object from OFFSET 3 (which is OFFSET 6) # Person.where(["user_name = :u", { u: user_name }]).fourth def fourth - find_nth(3, offset_index) + find_nth 3 end # Same as #fourth but raises ActiveRecord::RecordNotFound if no record @@ -217,7 +225,7 @@ module ActiveRecord # Person.offset(3).fifth # returns the fifth object from OFFSET 3 (which is OFFSET 7) # Person.where(["user_name = :u", { u: user_name }]).fifth def fifth - find_nth(4, offset_index) + find_nth 4 end # Same as #fifth but raises ActiveRecord::RecordNotFound if no record @@ -233,7 +241,7 @@ module ActiveRecord # Person.offset(3).forty_two # returns the forty-second object from OFFSET 3 (which is OFFSET 44) # Person.where(["user_name = :u", { u: user_name }]).forty_two def forty_two - find_nth(41, offset_index) + find_nth 41 end # Same as #forty_two but raises ActiveRecord::RecordNotFound if no record @@ -488,40 +496,49 @@ module ActiveRecord end end - def find_nth(index, offset) + def find_nth(index, offset = nil) + # TODO: once the offset argument is removed we rely on offset_index + # within find_nth_with_limit, rather than pass it in via + # find_nth_with_limit_and_offset + if offset + ActiveSupport::Deprecation.warn(<<-MSG.squish) + Passing an offset argument to find_nth is deprecated, + please use Relation#offset instead. + MSG + end if loaded? @records[index] else - offset += index - @offsets[offset] ||= find_nth_with_limit(offset, 1).first + offset ||= offset_index + @offsets[offset + index] ||= find_nth_with_limit_and_offset(index, 1, offset: offset).first end end def find_nth!(index) - find_nth(index, offset_index) or raise RecordNotFound.new("Couldn't find #{@klass.name} with [#{arel.where_sql(@klass.arel_engine)}]") + find_nth(index) or raise RecordNotFound.new("Couldn't find #{@klass.name} with [#{arel.where_sql(@klass.arel_engine)}]") end - def find_nth_with_limit(offset, limit) + def find_nth_with_limit(index, limit) + # TODO: once the offset argument is removed from find_nth, + # find_nth_with_limit_and_offset can be merged into this method relation = if order_values.empty? && primary_key order(arel_table[primary_key].asc) else self end - relation = relation.offset(offset) unless offset.zero? + relation = relation.offset(index) unless index.zero? relation.limit(limit).to_a end - def find_last + private + + def find_nth_with_limit_and_offset(index, limit, offset:) # :nodoc: if loaded? - @records.last + @records[index, limit] else - @last ||= - if limit_value - to_a.last - else - reverse_order.limit(1).to_a.first - end + index += offset + find_nth_with_limit(index, limit) end end end |