1 files changed, 55 insertions, 18 deletions

diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 5d4a045097..90a6a466fd 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -145,23 +145,15 @@ module ActiveRecord
     #
     #   [#<Person id:4>, #<Person id:3>, #<Person id:2>]
     def last(limit = nil)
-      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
+      if limit
+        if order_values.empty? && primary_key
+          order(arel_attribute(primary_key).desc).limit(limit).reverse
+        else
+          to_a.last(limit)
+        end
+      else
+        find_last
+      end
     end
 
     # Same as #last but raises ActiveRecord::RecordNotFound if no record
@@ -250,6 +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:
     #
@@ -522,7 +546,7 @@ module ActiveRecord
       # 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)
+                   order(arel_attribute(primary_key).asc)
                  else
                    self
                  end
@@ -531,6 +555,19 @@ module ActiveRecord
       relation.limit(limit).to_a
     end
 
+    def find_last
+      if loaded?
+        @records.last
+      else
+        @last ||=
+          if limit_value
+            to_a.last
+          else
+            reverse_order.limit(1).to_a.first
+          end
+      end
+    end
+
     private
 
     def find_nth_with_limit_and_offset(index, limit, offset:) # :nodoc: