Merge pull request #204 from edx/perf/pluck-not-map-voting-ids

Plucking instead of mapping.

models/user.rb

@@ -111,11 +111,11 @@ class User
   end
 
   def upvoted_ids
-    Content.up_voted_by(self).map(&:id)
+    Content.up_voted_by(self).pluck(:_id)
   end
 
   def downvoted_ids
-    Content.down_voted_by(self).map(&:id)
+    Content.down_voted_by(self).pluck(:_id)
   end
 
   def followers

spec/api/user_spec.rb

@@ -45,7 +45,12 @@ describe "app" do
         last_response.status.should == 400
       end
     end
+
     describe "GET /api/v1/users/:user_id" do
+      let(:author) { User.find_by(external_id: "1") }
+      let(:reader) { User.find_by(external_id: "2") }
+      let(:thread) { make_standalone_thread(author) }
+
       it "returns user information" do
         get "/api/v1/users/1"
         last_response.status.should == 200
@@ -54,10 +59,28 @@ describe "app" do
         res["external_id"].should == user1.external_id
         res["username"].should == user1.username
       end
+
       it "returns 404 if user does not exist" do
         get "/api/v1/users/3"
         last_response.status.should == 404
       end
+
+      it "returns no threads when user hasn't voted" do
+        get "/api/v1/users/1", complete: "true"
+        last_response.status.should == 200
+        res = parse(last_response.body)
+        res["upvoted_ids"].should == []
+      end
+
+      it "returns threads when user votes" do
+        reader.vote(thread, :up)
+
+        get "/api/v1/users/2", complete: "true"
+        last_response.status.should == 200
+        res = parse(last_response.body)
+        res["upvoted_ids"].should == [thread.id.to_s]
+      end
+
       describe "Returns threads_count and comments_count" do
           before(:each) { setup_10_threads }
 

spec/models/user_spec.rb

+require 'spec_helper'
+require 'unicode_shared_examples'
+
+describe User do
+  let(:author) { create_test_user(666) }
+  let(:reader) { create_test_user(667) }
+  let(:thread) { make_standalone_thread(author) }
+
+  before(:each) do
+    [Comment, CommentThread, User].each(&:delete_all).each(&:remove_indexes).each(&:create_indexes)
+  end
+
+  it "should have no votes if it never voted" do
+    reader.upvoted_ids.should == []
+  end
+
+  it "should have one vote if it voted once" do
+    reader.upvoted_ids.should == []
+    reader.vote(thread, :up)
+    reader.upvoted_ids.should == [thread._id]
+  end
+end

spec/spec_helper.rb

@@ -342,6 +342,17 @@ def make_comment(author, parent, text)
   comment
 end
 
+def make_standalone_thread(author)
+  make_thread(
+      author,
+      "standalone thread 0",
+      DFLT_COURSE_ID,
+      "pdq",
+      :discussion,
+      :standalone
+  )
+end
+
 # add standalone threads and comments to the @threads and @comments hashes
 # using the namespace "standalone t#{index}" for threads and "standalone t#{index} c#{i}" for comments
 # takes an index param if used within an iterator, otherwise will namespace using 0 for thread index