Query hints are no longer erased on explain. [ fix mongoid#84 ]

mattparlane · Oct 6, 2012 · 71c21c5 · 71c21c5
1 parent 7de7c50
commit 71c21c5
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Showing 3 changed files with 45 additions and 3 deletions.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -24,6 +24,8 @@
 
 * \#87 `Moped::BSON::ObjectId.legal?` now returns true for object ids.
 
+* \#84 Query hints are no longer wiped on explain.
+
 * \#60/\#80 Moped now gracefully handles replica set reconfig and crashes of the
   primary and secondary. By default, the node list will be refreshed every
   second and the operation will be retried up to 30 times. This is configurable

diff --git a/lib/moped/query.rb b/lib/moped/query.rb
@@ -89,12 +89,15 @@ def each
     #
     # @since 1.0.0
     def explain
+      hint, sort = operation.selector["$hint"], operation.selector["$orderby"]
       operation.selector = {
         "$query" => selector,
-        "$orderby" => operation.selector.fetch("$orderby", {}),
         "$explain" => true,
         "$limit" => operation.selector.fetch("$limit", 1).abs * -1
-      } and each { |doc| return doc }
+      }
+      operation.selector["$orderby"] = sort if sort
+      operation.selector["$hint"] = hint if hint
+      each { |doc| return doc }
     end
 
     # Get the first matching document.

diff --git a/spec/moped/query_spec.rb b/spec/moped/query_spec.rb
@@ -412,7 +412,6 @@
         it "updates to a mongo advanced selector" do
           operation.selector.should eq(
             "$query" => { created_at: { "$exists" => false }},
-            "$orderby" => {},
             "$explain" => true,
             "$limit" => -1
           )
@@ -426,6 +425,44 @@
           explain["nscannedObjects"].should eq(2)
         end
       end
+
+      context "when a hint exists" do
+
+        before do
+          2.times do |n|
+            users.insert({ likes: n })
+          end
+        end
+
+        let(:explain) do
+          users.find(likes: { "$exists" => false }).hint(_id: 1).explain
+        end
+
+        let(:stats) do
+          Support::Stats.collect { explain }
+        end
+
+        let(:operation) do
+          stats[node_for_reads].grep(Moped::Protocol::Query).last
+        end
+
+        it "updates to a mongo advanced selector" do
+          operation.selector.should eq(
+            "$query" => { likes: { "$exists" => false }},
+            "$explain" => true,
+            "$hint" => { _id: 1 },
+            "$limit" => -1
+          )
+        end
+
+        it "scans more than one document" do
+          explain["nscanned"].should eq(2)
+        end
+
+        it "scans more than one object" do
+          explain["nscannedObjects"].should eq(2)
+        end
+      end
     end
 
     describe "#each" do