SERVER-23473 Add collation parameter to the group command

2 files changed, 15 insertions, 0 deletions

diff --git a/src/mongo/db/commands/group_cmd.cpp b/src/mongo/db/commands/group_cmd.cpp
index 60eeac1feb7..ba0bfa49740 100644
--- a/src/mongo/db/commands/group_cmd.cpp
+++ b/src/mongo/db/commands/group_cmd.cpp
@@ -28,6 +28,7 @@
 
 #include "mongo/platform/basic.h"
 
+#include "mongo/bson/util/bson_extract.h"
 #include "mongo/db/auth/action_set.h"
 #include "mongo/db/auth/action_type.h"
 #include "mongo/db/auth/authorization_session.h"
@@ -227,6 +228,16 @@ private:
             // No key specified.  Use the entire object as the key.
         }
 
+        BSONElement collationElt;
+        Status collationEltStatus =
+            bsonExtractTypedField(p, "collation", BSONType::Object, &collationElt);
+        if (!collationEltStatus.isOK() && (collationEltStatus != ErrorCodes::NoSuchKey)) {
+            return collationEltStatus;
+        }
+        if (collationEltStatus.isOK()) {
+            request->collation = collationElt.embeddedObject().getOwned();
+        }
+
         BSONElement reduce = p["$reduce"];
         if (reduce.eoo()) {
             return Status(ErrorCodes::BadValue, "$reduce has to be set");
diff --git a/src/mongo/db/exec/group.h b/src/mongo/db/exec/group.h
index 4199bc20cd5..355cab91b9d 100644
--- a/src/mongo/db/exec/group.h
+++ b/src/mongo/db/exec/group.h
@@ -54,6 +54,10 @@ struct GroupRequest {
     // Empty is "keyPattern" is being used instead.
     std::string keyFunctionCode;
 
+    // The collation used for string comparisons. If empty, simple binary comparison with memcmp()
+    // is used.
+    BSONObj collation;
+
     // A Javascript function that takes a (input document, group result) pair and
     // updates the group result document.
     std::string reduceCode;