Merge pull request #5 from manyfold3d/granted-to

Add ability to finding objects that subjects have some permission on

README.md

@@ -114,6 +114,14 @@ document.revoke_permission("viewer", user)
 document.revoke_all_permissions(user)
 ```
 
+### Finding objects
+
+You can get lists of objects that a user has some permission on:
+
+```
+Document.granted_to "viewer", user
+# => All the documents that user has "viewer" permission on
+```
 
 ## Development
 

app/models/concerns/caber/object.rb

@@ -8,6 +8,14 @@ module Caber::Object
     def self.can_grant_permissions_to(model)
       has_many :"permitted_#{model.name.pluralize.parameterize}", through: :caber_relations, source: :subject, source_type: model.name
     end
+
+    scope :granted_to, ->(permission, subject) {
+                         includes(:caber_relations).where(
+                           "caber_relations.subject_id": subject.id,
+                           "caber_relations.subject_type": subject.class.name,
+                           "caber_relations.permission": permission
+                         )
+                       }
   end
 
   def grant_permission_to(permission, subject)

spec/models/caber/relation_spec.rb

@@ -45,6 +45,14 @@
     it "includes Alice in a list of users with viewer permission for the object" do
       expect(object.permitted_users.with_permission("viewer")).to include alice
     end
+
+    it "can get a list of objects that Alice has permission on" do
+      expect(Document.granted_to("viewer", alice)).to include object
+    end
+
+    it "can get a list of objects that Alice one of many permissions on" do
+      expect(Document.granted_to(["viewer", "owner"], alice)).to include object
+    end
   end
 
   context "with multiple objects" do
@@ -61,6 +69,10 @@
     it "does not include second (ungranted) object in Alices permitted object list" do
       expect(alice.permitted_documents.with_permission("viewer")).not_to include object_two
     end
+
+    it "does not include second object in list of objects that Alice has permission on" do
+      expect(Document.granted_to("viewer", alice)).not_to include object_two
+    end
   end
 
   context "checking more than one permission at once" do