Support custom_payload for Rails 5 API's ActionController::API

README.md

@@ -65,6 +65,15 @@ Rails.application.configure do
 end
 ```
 
+If you're using Rails 5's API-only mode and inherit from `ActionController::API`:
+
+```ruby
+# config/initializers/lograge.rb
+Rails.application.configure do
+  config.lograge.base_controller_class = ActionController::API
+end
+```
+
 You can also add a hook for own custom data
 
 ```ruby

lib/lograge.rb

@@ -144,10 +144,11 @@ def attach_to_action_controller
 
   def setup_custom_payload
     return unless lograge_config.custom_payload_method.respond_to?(:call)
-    append_payload_method = ActionController::Base.instance_method(:append_info_to_payload)
+    base_controller_class = lograge_config.base_controller_class || ActionController::Base
+    append_payload_method = base_controller_class.instance_method(:append_info_to_payload)
     custom_payload_method = lograge_config.custom_payload_method
 
-    ActionController::Base.send(:define_method, :append_info_to_payload) do |payload|
+    base_controller_class.send(:define_method, :append_info_to_payload) do |payload|
       append_payload_method.bind(self).call(payload)
       payload[:custom_payload] = custom_payload_method.call(self)
     end

spec/lograge_spec.rb

@@ -93,6 +93,7 @@
   end
 
   describe 'handling custom_payload option' do
+    let(:controller_class) { 'ActionController::Base' }
     let(:app_config) do
       config_obj = ActiveSupport::OrderedOptions.new.tap do |config|
         config.action_dispatch = double(rack_cache: false)
@@ -119,12 +120,29 @@ def current_user_id
     subject { payload.dup }
 
     before do
-      stub_const('ActionController::Base', controller)
+      stub_const(controller_class, controller)
       Lograge.setup(app_config)
-      ActionController::Base.new.append_info_to_payload(subject)
+      controller_class.constantize.new.append_info_to_payload(subject)
     end
 
     it { should eq(payload.merge(appended: true, custom_payload: { user_id: '24601' })) }
+
+    context 'when base_controller_class option is set' do
+      let(:controller_class) { 'ActionController::API' }
+      let(:app_config) do
+        config_obj = ActiveSupport::OrderedOptions.new.tap do |config|
+          config.action_dispatch = double(rack_cache: false)
+          config.lograge = Lograge::OrderedOptions.new
+          config.lograge.base_controller_class = controller_class.constantize
+          config.lograge.custom_payload do |c|
+            { user_id: c.current_user_id }
+          end
+        end
+        double(config: config_obj)
+      end
+
+      it { should eq(payload.merge(appended: true, custom_payload: { user_id: '24601' })) }
+    end
   end
 
   describe 'deprecated log_format interpreter' do