refactor: abstract resources (#3777)

* refactor: abstract resources

* lint

Author: Paul-Bob

app/avo/base_resource.rb

@@ -1,5 +1,7 @@
 module Avo
   class BaseResource < Avo::Resources::Base
+    abstract_resource!
+
     # Users can override this class to add custom methods for all resources.
   end
 end

lib/avo/concerns/abstract_resource.rb

@@ -0,0 +1,13 @@
+module Avo
+  module Concerns
+    module AbstractResource
+      extend ActiveSupport::Concern
+
+      class_methods do
+        def abstract_resource! = @abstract_resource = true
+
+        def is_abstract? = @abstract_resource == true
+      end
+    end
+  end
+end

lib/avo/resources/array_resource.rb

@@ -1,6 +1,8 @@
 module Avo
   module Resources
     class ArrayResource < Base
+      abstract_resource!
+
       extend ActiveSupport::DescendantsTracker
 
       include Avo::Concerns::FindAssociationField

lib/avo/resources/base.rb

@@ -19,6 +19,9 @@ class Base
       include Avo::Concerns::HasDiscreetInformation
       include Avo::Concerns::RowControlsConfiguration
       include Avo::Concerns::SafeCall
+      include Avo::Concerns::AbstractResource
+
+      abstract_resource!
 
       # Avo::Current methods
       delegate :context, to: Avo::Current
@@ -84,6 +87,8 @@ def current_user
       class_attribute :default_sort_direction, default: :desc
       class_attribute :external_link, default: nil
 
+      class_attribute :abstract, default: false
+
       # EXTRACT:
       class_attribute :ordering
 

lib/avo/resources/resource_manager.rb

@@ -40,12 +40,9 @@ def fetch_resources
             load_resources_namespace
           end
 
-          # All descendants from Avo::Resources::Base except the internal ones
-          Base.descendants - internal_resources
-        end
+          # All descendants from Avo::Resources::Base except the internal abstract ones
 
-        def internal_resources
-          [Avo::BaseResource, Avo::Resources::ArrayResource]
+          Base.descendants.reject { _1.is_abstract? }
         end
 
         def load_resources_namespace