Merge pull request #47431 from skipkayhil/make-shared-three-tier-aware

Allow 3-tier shared config in database.yml

railties/lib/rails/application/configuration.rb

@@ -417,8 +417,14 @@ def database_configuration
           if (shared = loaded_yaml.delete("shared"))
             loaded_yaml.each do |env, config|
               if config.is_a?(Hash) && config.values.all?(Hash)
-                config.map do |name, sub_config|
-                  sub_config.reverse_merge!(shared)
+                if shared.is_a?(Hash) && shared.values.all?(Hash)
+                  config.map do |name, sub_config|
+                    sub_config.reverse_merge!(shared[name])
+                  end
+                else
+                  config.map do |name, sub_config|
+                    sub_config.reverse_merge!(shared)
+                  end
                 end
               else
                 config.reverse_merge!(shared)

railties/test/application/configuration_test.rb

@@ -2180,6 +2180,28 @@ def index
       assert_equal "dev_db",  ar_config["development"]["primary"]["database"]
     end
 
+    test "loads database.yml using 3-tier shared keys with a 3-tier config" do
+      app_file "config/database.yml", <<-YAML
+        shared:
+          one:
+            migrations_path: "db/one"
+          two:
+            migrations_path: "db/two"
+
+        development:
+          one:
+            adapter: sqlite3
+          two:
+            adapter: sqlite3
+      YAML
+
+      app "development"
+
+      ar_config = Rails.configuration.database_configuration
+      assert_equal "db/one", ar_config["development"]["one"]["migrations_path"]
+      assert_equal "db/two", ar_config["development"]["two"]["migrations_path"]
+    end
+
     test "config.action_mailer.show_previews defaults to true in development" do
       app "development"