Make engines aware of AR::Base table name prefix

Author: chaadow

railties/CHANGELOG.md

@@ -1,3 +1,9 @@
+*   Fix isolated engines to take `ActiveRecord::Base.table_name_prefix` into consideration.
+    This will allow for engine defined models, such as inside Active Storage, to respect
+    Active Record table name prefix configuration.
+
+    *Chedli Bourguiba*
+
 *   Fix running `db:system:change` when app has no Dockerfile.
 
     *Hartley McGuire*

railties/lib/rails/engine.rb

@@ -396,6 +396,12 @@ def isolate_namespace(mod)
 
             unless mod.respond_to?(:table_name_prefix)
               define_method(:table_name_prefix) { "#{name}_" }
+
+              ActiveSupport.on_load(:active_record) do
+                mod.singleton_class.redefine_method(:table_name_prefix) do
+                  "#{ActiveRecord::Base.table_name_prefix}#{name}_"
+                end
+              end
             end
 
             unless mod.respond_to?(:use_relative_model_naming?)

railties/test/railties/engine_test.rb

@@ -1290,6 +1290,32 @@ class Engine < ::Rails::Engine
       assert_equal "foo", Bukkits.table_name_prefix
     end
 
+    test "take ActiveRecord table_name_prefix into consideration when defining table_name_prefix" do
+      @plugin.write "lib/bukkits.rb", <<-RUBY
+        module Bukkits
+          class Engine < ::Rails::Engine
+            isolate_namespace(Bukkits)
+          end
+        end
+      RUBY
+
+      @plugin.write "app/models/bukkits/post.rb", <<-RUBY
+        module Bukkits
+          class Post < ActiveRecord::Base
+          end
+        end
+      RUBY
+
+      add_to_config <<-RUBY
+        config.active_record.table_name_prefix = "ar_prefix_"
+      RUBY
+
+      boot_rails
+
+      assert_equal "ar_prefix_bukkits_posts", Bukkits::Post.table_name
+      assert_equal "ar_prefix_bukkits_", Bukkits.table_name_prefix
+    end
+
     test "fetching engine by path" do
       @plugin.write "lib/bukkits.rb", <<-RUBY
         module Bukkits