add automatic detection of the policy class

1 files changed, 15 insertions, 1 deletions

diff --git a/app/policies/base_policy.rb b/app/policies/base_policy.rb
index e1757d97e89..12f60d8f76e 100644
--- a/app/policies/base_policy.rb
+++ b/app/policies/base_policy.rb
@@ -4,7 +4,21 @@ class BasePolicy
   end
 
   def self.class_for(subject)
-    "#{subject.class.name}Policy".constantize
+    subject.class.ancestors.each do |klass|
+      next unless klass.name
+
+      begin
+        policy_class = "#{klass.name}Policy".constantize
+
+        # NB: the < operator here tests whether policy_class
+        # inherits from BasePolicy
+        return policy_class if policy_class < BasePolicy
+      rescue NameError
+        nil
+      end
+    end
+
+    raise "no policy for #{subject.class.name}"
   end
 
   attr_reader :user, :subject