Use the new `foreign_key` option on `references` in generators

Changes `rails g model Post user:references` from

    def change
      create_table :posts do |t|
        t.references :user, index: true
      end

      add_foreign_key :posts, :users
    end

to

    def change
      create_table :posts do |t|
        t.references :user, index: true, foreign_key: true
      end
    end

Changes `rails g migration add_user_to_posts user:references` from

    def change
      add_reference :posts, :users, index: true
      add_foreign_key :posts, :users
    end

to

    def change
      add_reference :posts, :users, index: true, foreign_key: true
    end

5 files changed, 20 insertions, 14 deletions

diff --git a/activerecord/lib/rails/generators/active_record/migration/templates/create_table_migration.rb b/activerecord/lib/rails/generators/active_record/migration/templates/create_table_migration.rb
index fb0fbb4759..f7bf6987c4 100644
--- a/activerecord/lib/rails/generators/active_record/migration/templates/create_table_migration.rb
+++ b/activerecord/lib/rails/generators/active_record/migration/templates/create_table_migration.rb
@@ -15,8 +15,5 @@ class <%= migration_class_name %> < ActiveRecord::Migration
 <% attributes_with_index.each do |attribute| -%>
     add_index :<%= table_name %>, :<%= attribute.index_name %><%= attribute.inject_index_options %>
 <% end -%>
-<% attributes.select(&:reference?).reject(&:polymorphic?).each do |attribute| -%>
-    add_foreign_key :<%= table_name %>, :<%= attribute.name.pluralize %>
-<% end -%>
   end
 end
diff --git a/activerecord/lib/rails/generators/active_record/migration/templates/migration.rb b/activerecord/lib/rails/generators/active_record/migration/templates/migration.rb
index 7df9bcad25..ae9c74fd05 100644
--- a/activerecord/lib/rails/generators/active_record/migration/templates/migration.rb
+++ b/activerecord/lib/rails/generators/active_record/migration/templates/migration.rb
@@ -4,9 +4,6 @@ class <%= migration_class_name %> < ActiveRecord::Migration
 <% attributes.each do |attribute| -%>
   <%- if attribute.reference? -%>
     add_reference :<%= table_name %>, :<%= attribute.name %><%= attribute.inject_options %>
-    <%- unless attribute.polymorphic? -%>
-    add_foreign_key :<%= table_name %>, :<%= attribute.name.pluralize %>
-    <%- end -%>
   <%- else -%>
     add_column :<%= table_name %>, :<%= attribute.name %>, :<%= attribute.type %><%= attribute.inject_options %>
     <%- if attribute.has_index? -%>
@@ -29,9 +26,6 @@ class <%= migration_class_name %> < ActiveRecord::Migration
 <%- if migration_action -%>
   <%- if attribute.reference? -%>
     remove_reference :<%= table_name %>, :<%= attribute.name %><%= attribute.inject_options %>
-    <%- unless attribute.polymorphic? -%>
-    remove_foreign_key :<%= table_name %>, :<%= attribute.name.pluralize %>
-    <%- end -%>
   <%- else -%>
     <%- if attribute.has_index? -%>
     remove_index :<%= table_name %>, :<%= attribute.index_name %><%= attribute.inject_index_options %>
diff --git a/railties/lib/rails/generators/generated_attribute.rb b/railties/lib/rails/generators/generated_attribute.rb
index f16bd8e082..77a3dbf9a2 100644
--- a/railties/lib/rails/generators/generated_attribute.rb
+++ b/railties/lib/rails/generators/generated_attribute.rb
@@ -159,6 +159,10 @@ module Rails
             options.delete(:required)
             options[:null] = false
           end
+
+          if reference? && !polymorphic?
+            options[:foreign_key] = true
+          end
         end
       end
     end
diff --git a/railties/test/generators/migration_generator_test.rb b/railties/test/generators/migration_generator_test.rb
index c2c8e2abad..0803699968 100644
--- a/railties/test/generators/migration_generator_test.rb
+++ b/railties/test/generators/migration_generator_test.rb
@@ -189,8 +189,9 @@ class MigrationGeneratorTest < Rails::Generators::TestCase
 
     assert_migration "db/migrate/#{migration}.rb" do |content|
       assert_method :change, content do |change|
-        assert_match(/add_foreign_key :books, :authors/, change)
-        assert_no_match(/add_foreign_key :books, :distributors/, change)
+        assert_match(/add_reference :books, :author,.*\sforeign_key: true/, change)
+        assert_match(/add_reference :books, :distributor/, change) # sanity check
+        assert_no_match(/add_reference :books, :distributor,.*\sforeign_key: true/, change)
       end
     end
   end
diff --git a/railties/test/generators/model_generator_test.rb b/railties/test/generators/model_generator_test.rb
index ac7a0acf6b..9dc438fe3c 100644
--- a/railties/test/generators/model_generator_test.rb
+++ b/railties/test/generators/model_generator_test.rb
@@ -407,13 +407,23 @@ class ModelGeneratorTest < Rails::Generators::TestCase
     end
   end
 
+  def test_foreign_key_is_not_added_for_non_references
+    run_generator ["account", "supplier:string"]
+
+    assert_migration "db/migrate/create_accounts.rb" do |m|
+      assert_method :change, m do |up|
+        assert_no_match(/foreign_key/, up)
+      end
+    end
+  end
+
   def test_foreign_key_is_added_for_references
     run_generator ["account", "supplier:belongs_to", "user:references"]
 
     assert_migration "db/migrate/create_accounts.rb" do |m|
       assert_method :change, m do |up|
-        assert_match(/add_foreign_key :accounts, :suppliers/, up)
-        assert_match(/add_foreign_key :accounts, :users/, up)
+        assert_match(/t\.belongs_to :supplier,.*\sforeign_key: true/, up)
+        assert_match(/t\.references :user,.*\sforeign_key: true/, up)
       end
     end
   end
@@ -423,7 +433,7 @@ class ModelGeneratorTest < Rails::Generators::TestCase
 
     assert_migration "db/migrate/create_accounts.rb" do |m|
       assert_method :change, m do |up|
-        assert_no_match(/add_foreign_key :accounts, :suppliers/, up)
+        assert_no_match(/foreign_key/, up)
       end
     end
   end