SERVER-16830 Fix LiteParsedQuery find command object "hint" parsing

4 files changed, 20 insertions, 7 deletions

diff --git a/jstests/core/explain_shell_helpers.js b/jstests/core/explain_shell_helpers.js
index 6ed86f8c6b0..8b49588ff8e 100644
--- a/jstests/core/explain_shell_helpers.js
+++ b/jstests/core/explain_shell_helpers.js
@@ -122,9 +122,15 @@ assert(planHasStage(explain.queryPlanner.winningPlan, "SORT"));
 explain = t.explain().find().hint({a: 1}).finish();
 assert.commandWorked(explain);
 assert(isIxscan(explain.queryPlanner.winningPlan));
+explain = t.explain().find().hint("a_1").finish();
+assert.commandWorked(explain);
+assert(isIxscan(explain.queryPlanner.winningPlan));
 explain = t.find().hint({a: 1}).explain();
 assert.commandWorked(explain);
 assert(isIxscan(explain.queryPlanner.winningPlan));
+explain = t.find().hint("a_1").explain();
+assert.commandWorked(explain);
+assert(isIxscan(explain.queryPlanner.winningPlan));
 
 // .min()
 explain = t.explain().find().min({a: 1}).finish();
diff --git a/src/mongo/db/query/lite_parsed_query.cpp b/src/mongo/db/query/lite_parsed_query.cpp
index 6e062150abd..d002850122b 100644
--- a/src/mongo/db/query/lite_parsed_query.cpp
+++ b/src/mongo/db/query/lite_parsed_query.cpp
@@ -116,7 +116,7 @@ namespace mongo {
                     hintObj = cmdObj["hint"].Obj().getOwned();
                 }
                 else if (String == el.type()) {
-                    hintObj = el.wrap();
+                    hintObj = el.wrap("$hint");
                 }
                 else {
                     return Status(ErrorCodes::BadValue,
@@ -774,11 +774,13 @@ namespace mongo {
                     if (e.isABSONObj()) {
                         _hint = e.embeddedObject().getOwned();
                     }
-                    else {
-                        // Hint can be specified as an object or as a string.  Wrap takes care of
-                        // it.
+                    else if (String == e.type()) {
                         _hint = e.wrap();
                     }
+                    else {
+                        return Status(ErrorCodes::BadValue,
+                                      "$hint must be either a string or nested object");
+                    }
                 }
                 else if (str::equals("returnKey", name)) {
                     // Won't throw.
diff --git a/src/mongo/db/query/lite_parsed_query.h b/src/mongo/db/query/lite_parsed_query.h
index 8e8808d9ad5..d2da40e6684 100644
--- a/src/mongo/db/query/lite_parsed_query.h
+++ b/src/mongo/db/query/lite_parsed_query.h
@@ -108,7 +108,7 @@ namespace mongo {
         };
 
         /**
-         * Parses a count command object, 'cmdObj'. Caller must indicate whether or not
+         * Parses a find command object, 'cmdObj'. Caller must indicate whether or not
          * this lite parsed query is an explained query or not via 'isExplain'.
          *
          * On success, fills in the out-parameter 'parsedQuery' and returns an OK status.
@@ -262,10 +262,14 @@ namespace mongo {
         BSONObj _filter;
         BSONObj _sort;
         BSONObj _proj;
-        BSONObj _hint;
         bool _wantMore;
         bool _explain;
 
+        // The hint provided, if any.  If the hint was by index key pattern, the value of '_hint' is
+        // the key pattern hinted.  If the hint was by index name, the value of '_hint' is
+        // {$hint: <String>}, where <String> is the index name hinted.
+        BSONObj _hint;
+
         Options _options;
     };
 
diff --git a/src/mongo/db/query/lite_parsed_query_test.cpp b/src/mongo/db/query/lite_parsed_query_test.cpp
index 7ec42f2e0ad..2b5840181f7 100644
--- a/src/mongo/db/query/lite_parsed_query_test.cpp
+++ b/src/mongo/db/query/lite_parsed_query_test.cpp
@@ -308,7 +308,8 @@ namespace {
         ASSERT_OK(status);
         scoped_ptr<LiteParsedQuery> lpq(rawLpq);
 
-        ASSERT_EQUALS("foo_1", lpq->getHint().firstElement().str());
+        BSONObj hintObj = lpq->getHint();
+        ASSERT_EQUALS(BSON("$hint" << "foo_1"), hintObj);
     }
 
     TEST(LiteParsedQueryTest, ParseFromCommandValidSortProj) {