Allow overriding policy class on authorize method

README.md

@@ -133,6 +133,18 @@ def publish
 end
 ```
 
+You can pass an argument to override the policy class if necessary. For example:
+
+```ruby
+def create
+  @publication = find_publication # assume this method returns any model that behaves like a publication
+  # @publication.class => Post
+  authorize @publication, policy_class: PublicationPolicy
+  @publication.publish!
+  redirect_to @publication
+end
+```
+
 If you don't have an instance for the first argument to `authorize`, then you can pass
 the class. For example:
 

lib/pundit.rb

@@ -189,14 +189,15 @@ protected
   # @param record [Object] the object we're checking permissions of
   # @param query [Symbol, String] the predicate method to check on the policy (e.g. `:show?`).
   #   If omitted then this defaults to the Rails controller action name.
+  # @param policy_class [Class] the policy class we wan't to force use of
   # @raise [NotAuthorizedError] if the given query method returned false
   # @return [Object] Always returns the passed object record
-  def authorize(record, query = nil)
+  def authorize(record, query = nil, policy_class: nil)
     query ||= "#{action_name}?"
 
     @_pundit_policy_authorized = true
 
-    policy = policy(record)
+    policy = policy_class ? policy_class.new(pundit_user, record) : policy(record)
 
     raise NotAuthorizedError, query: query, record: record, policy: policy unless policy.public_send(query)
 

spec/pundit_spec.rb

@@ -375,6 +375,10 @@ describe Pundit do
       expect { controller.authorize(post, :destroy?) }.to raise_error(Pundit::NotAuthorizedError)
     end
 
+    it "can be given a different policy class" do
+      expect(controller.authorize(post, :create?, policy_class: PublicationPolicy)).to be_truthy
+    end
+
     it "works with anonymous class policies" do
       expect(controller.authorize(article_tag, :show?)).to be_truthy
       expect { controller.authorize(article_tag, :destroy?) }.to raise_error(Pundit::NotAuthorizedError)

spec/spec_helper.rb

@@ -91,6 +91,18 @@ class CommentPolicy < Struct.new(:user, :comment)
   end
 end
 
+class PublicationPolicy < Struct.new(:user, :publication)
+  class Scope < Struct.new(:user, :scope)
+    def resolve
+      scope
+    end
+  end
+
+  def create?
+    true
+  end
+end
+
 class Comment
   extend ActiveModel::Naming
 end