fix: lazy constantize relation resources (#492)

Author: bguban

lib/graphiti/sideload.rb

@@ -21,7 +21,7 @@ def initialize(name, opts)
       @name = name
       validate_options!(opts)
       @parent_resource_class = opts[:parent_resource]
-      @resource_class = opts[:resource]
+      @resource_class_name = opts[:resource]
       @primary_key = opts[:primary_key]
       @foreign_key = opts[:foreign_key]
       @type = opts[:type]
@@ -177,7 +177,8 @@ def association_name
     end
 
     def resource_class
-      @resource_class ||= infer_resource_class
+      @resource_class ||= (@resource_class_name.is_a?(String) ? @resource_class_name.constantize : @resource_class_name) ||
+        infer_resource_class
     end
 
     def scope(parents)

spec/fixtures/legacy.rb

@@ -225,6 +225,7 @@ class TagResource < ApplicationResource
   end
 
   class UserResource < ApplicationResource
+    has_many :my_books, resource: "Legacy::BookResource"
   end
 
   class BookResource < ApplicationResource