Deal with Nic model by explicit preloading

app/models/concerns/foreman/sti.rb

@@ -2,10 +2,6 @@ module Foreman
   module STI
     extend ActiveSupport::Concern
 
-    prepended do
-      cattr_accessor :preloaded, instance_accessor: false
-    end
-
     class_methods do
       # ensures that the correct STI object is created when :type is passed.
       def new(attributes = nil, &block)

app/models/nic/bmc.rb

@@ -64,6 +64,4 @@ def validate_bmc_proxy
       errors.add(:type, e.message)
     end
   end
-
-  Base.register_type(BMC)
 end

app/models/nic/bond.rb

@@ -19,6 +19,4 @@ def self.humanized_name
       N_('Bond')
     end
   end
-
-  Base.register_type(Bond)
 end

app/models/nic/bridge.rb

@@ -6,6 +6,4 @@ def self.humanized_name
       N_('Bridge')
     end
   end
-
-  Base.register_type(Bridge)
 end

app/models/nic/managed.rb

@@ -119,6 +119,4 @@ def setup_clone
       @old
     end
   end
-
-  Base.register_type(Managed)
 end

config/initializers/foreman.rb

@@ -56,3 +56,14 @@
 
   ReportImporter.register_smart_proxy_feature("Puppet")
 end
+
+# Preload here all classes which use Foreman::STI and using registration methods
+# E.g. Base.register_type(BMC)
+# Some constants that use such classes may be defined before all the related classes/models are loaded and registered
+# E.g. InterfaceTypeMapper::ALLOWED_TYPE_NAMES
+Rails.application.reloader.to_prepare do
+  Nic::Base.register_type(Nic::Managed)
+  Nic::Base.register_type(Nic::BMC)
+  Nic::Base.register_type(Nic::Bond)
+  Nic::Base.register_type(Nic::Bridge)
+end