Use flat_map { } instead of map {}.flatten

9 files changed, 13 insertions, 13 deletions

diff --git a/activerecord/lib/active_record/associations/join_dependency.rb b/activerecord/lib/active_record/associations/join_dependency.rb
index cd366ac8b7..16491cbee7 100644
--- a/activerecord/lib/active_record/associations/join_dependency.rb
+++ b/activerecord/lib/active_record/associations/join_dependency.rb
@@ -35,12 +35,12 @@ module ActiveRecord
       end
 
       def columns
-        join_parts.collect { |join_part|
+        join_parts.flat_map { |join_part|
           table = join_part.aliased_table
           join_part.column_names_with_alias.collect{ |column_name, aliased_name|
             table[column_name].as Arel.sql(aliased_name)
           }
-        }.flatten
+        }
       end
 
       def instantiate(rows)
diff --git a/activerecord/lib/active_record/associations/preloader.rb b/activerecord/lib/active_record/associations/preloader.rb
index ce5bf15f10..9cbc117945 100644
--- a/activerecord/lib/active_record/associations/preloader.rb
+++ b/activerecord/lib/active_record/associations/preloader.rb
@@ -106,7 +106,7 @@ module ActiveRecord
       def preload_hash(association)
         association.each do |parent, child|
           Preloader.new(records, parent, preload_scope).run
-          Preloader.new(records.map { |record| record.send(parent) }.flatten, child).run
+          Preloader.new(records.flat_map { |record| record.send(parent) }, child).run
         end
       end
 
diff --git a/activerecord/lib/active_record/associations/preloader/association.rb b/activerecord/lib/active_record/associations/preloader/association.rb
index cbf5e734ea..358d84513c 100644
--- a/activerecord/lib/active_record/associations/preloader/association.rb
+++ b/activerecord/lib/active_record/associations/preloader/association.rb
@@ -77,7 +77,7 @@ module ActiveRecord
             # Some databases impose a limit on the number of ids in a list (in Oracle it's 1000)
             # Make several smaller queries if necessary or make one query if the adapter supports it
             sliced  = owner_keys.each_slice(model.connection.in_clause_length || owner_keys.size)
-            records = sliced.map { |slice| records_for(slice).to_a }.flatten
+            records = sliced.flat_map { |slice| records_for(slice).to_a }
           end
 
           # Each record may have multiple owners, and vice-versa
diff --git a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
index 8c83c4f5db..dcb89178f7 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb
@@ -448,7 +448,7 @@ module ActiveRecord
       end
 
       def bulk_change_table(table_name, operations) #:nodoc:
-        sqls = operations.map do |command, args|
+        sqls = operations.flat_map do |command, args|
           table, arguments = args.shift, args
           method = :"#{command}_sql"
 
@@ -457,7 +457,7 @@ module ActiveRecord
           else
             raise "Unknown method called : #{method}(#{arguments.inspect})"
           end
-        end.flatten.join(", ")
+        end.join(", ")
 
         execute("ALTER TABLE #{quote_table_name(table_name)} #{sqls}")
       end
diff --git a/activerecord/lib/active_record/observer.rb b/activerecord/lib/active_record/observer.rb
index 6b2f6f98a5..6fe98a8f6d 100644
--- a/activerecord/lib/active_record/observer.rb
+++ b/activerecord/lib/active_record/observer.rb
@@ -99,7 +99,7 @@ module ActiveRecord
 
       def observed_classes
         klasses = super
-        klasses + klasses.map { |klass| klass.descendants }.flatten
+        klasses + klasses.flat_map { |klass| klass.descendants }
       end
 
       def add_observer!(klass)
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 3c59bd8a68..21c2b02b7e 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -782,7 +782,7 @@ module ActiveRecord
     def reverse_sql_order(order_query)
       order_query = ["#{quoted_table_name}.#{quoted_primary_key} ASC"] if order_query.empty?
 
-      order_query.map do |o|
+      order_query.flat_map do |o|
         case o
         when Arel::Nodes::Ordering
           o.reverse
@@ -794,7 +794,7 @@ module ActiveRecord
         else
           o
         end
-      end.flatten
+      end
     end
 
     def array_of_strings?(o)
diff --git a/activerecord/test/cases/associations/callbacks_test.rb b/activerecord/test/cases/associations/callbacks_test.rb
index 2d0d4541b4..0463b7d046 100644
--- a/activerecord/test/cases/associations/callbacks_test.rb
+++ b/activerecord/test/cases/associations/callbacks_test.rb
@@ -138,7 +138,7 @@ class AssociationCallbacksTest < ActiveRecord::TestCase
       activerecord.reload
       assert activerecord.developers_with_callbacks.size == 2
     end
-    log_array = activerecord.developers_with_callbacks.collect {|d| ["before_removing#{d.id}","after_removing#{d.id}"]}.flatten.sort
+    log_array = activerecord.developers_with_callbacks.flat_map {|d| ["before_removing#{d.id}","after_removing#{d.id}"]}.sort
     assert activerecord.developers_with_callbacks.clear
     assert_equal log_array, activerecord.developers_log.sort
   end
diff --git a/activerecord/test/cases/associations/has_many_through_associations_test.rb b/activerecord/test/cases/associations/has_many_through_associations_test.rb
index f0582a3090..c61ed61f1e 100644
--- a/activerecord/test/cases/associations/has_many_through_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_through_associations_test.rb
@@ -597,7 +597,7 @@ class HasManyThroughAssociationsTest < ActiveRecord::TestCase
     sarah = Person.create!(:first_name => 'Sarah', :primary_contact_id => people(:susan).id, :gender => 'F', :number1_fan_id => 1)
     john = Person.create!(:first_name => 'John', :primary_contact_id => sarah.id, :gender => 'M', :number1_fan_id => 1)
     assert_equal sarah.agents, [john]
-    assert_equal people(:susan).agents.map(&:agents).flatten, people(:susan).agents_of_agents
+    assert_equal people(:susan).agents.flat_map(&:agents), people(:susan).agents_of_agents
   end
 
   def test_associate_existing_with_nonstandard_primary_key_on_belongs_to
diff --git a/activerecord/test/cases/autosave_association_test.rb b/activerecord/test/cases/autosave_association_test.rb
index fd4f09ab36..8d10fe5fdf 100644
--- a/activerecord/test/cases/autosave_association_test.rb
+++ b/activerecord/test/cases/autosave_association_test.rb
@@ -50,9 +50,9 @@ class TestAutosaveAssociationsInGeneral < ActiveRecord::TestCase
   end
 
   def callbacks_for_model(model)
-    model.instance_variables.grep(/_callbacks$/).map do |ivar|
+    model.instance_variables.grep(/_callbacks$/).flat_map do |ivar|
       model.instance_variable_get(ivar)
-    end.flatten
+    end
   end
 end