Expose resource as an instance variable (#2478)

There's a few cases where it'd be helpful to be able to refer to the
resource on the current action. This does that as `@resources` or as
`@resource`.

To show this in use, we include a sample of an audit log which refers to
`@resource`.

Author: goosys

app/controllers/administrate/application_controller.rb

@@ -9,6 +9,7 @@ def index
       resources = apply_collection_includes(resources)
       resources = order.apply(resources)
       resources = paginate_resources(resources)
+      @resources = resources
       page = Administrate::Page::Collection.new(dashboard, order: order)
       filters = Administrate::Search.new(scoped_resource, dashboard, search_term).valid_filters
 
@@ -22,27 +23,29 @@ def index
     end
 
     def show
+      @resource = resource = requested_resource
       render locals: {
-        page: Administrate::Page::Show.new(dashboard, requested_resource)
+        page: Administrate::Page::Show.new(dashboard, resource)
       }
     end
 
     def new
-      resource = new_resource
+      @resource = resource = new_resource
       authorize_resource(resource)
       render locals: {
         page: Administrate::Page::Form.new(dashboard, resource)
       }
     end
 
     def edit
+      @resource = resource = requested_resource
       render locals: {
-        page: Administrate::Page::Form.new(dashboard, requested_resource)
+        page: Administrate::Page::Form.new(dashboard, resource)
       }
     end
 
     def create
-      resource = new_resource(resource_params)
+      @resource = resource = new_resource(resource_params)
       authorize_resource(resource)
 
       if resource.save
@@ -59,26 +62,28 @@ def create
     end
 
     def update
-      if requested_resource.update(resource_params)
+      @resource = resource = requested_resource
+      if resource.update(resource_params)
         redirect_to(
-          after_resource_updated_path(requested_resource),
+          after_resource_updated_path(resource),
           notice: translate_with_resource("update.success"),
           status: :see_other
         )
       else
         render :edit, locals: {
-          page: Administrate::Page::Form.new(dashboard, requested_resource)
+          page: Administrate::Page::Form.new(dashboard, resource)
         }, status: :unprocessable_entity
       end
     end
 
     def destroy
-      if requested_resource.destroy
+      @resource = resource = requested_resource
+      if resource.destroy
         flash[:notice] = translate_with_resource("destroy.success")
       else
-        flash[:error] = requested_resource.errors.full_messages.join("<br/>")
+        flash[:error] = resource.errors.full_messages.join("<br/>")
       end
-      redirect_to after_resource_destroyed_path(requested_resource), status: :see_other
+      redirect_to after_resource_destroyed_path(resource), status: :see_other
     end
 
     private

spec/example_app/app/controllers/admin/application_controller.rb

@@ -32,5 +32,22 @@ def authenticate_admin
     def pundit_user
       @current_user
     end
+
+    after_action :audit_log, only: %i[create update destroy]
+
+    def audit_log
+      if (resource = @resource)
+        Rails.logger.info(
+          sprintf(
+            "Audit Log: %<action>s %<class>s #%<id>d by %<user>s at %<time>s",
+            action: action_name.capitalize,
+            class: resource.class,
+            id: resource.id || 0,
+            user: pundit_user.name,
+            time: Time.zone.now.to_s
+          )
+        )
+      end
+    end
   end
 end