2 files changed, 15 insertions, 6 deletions
diff --git a/src/mongo/db/s/operation_shard_version.cpp b/src/mongo/db/s/operation_shard_version.cpp
index d51ae7d9cb8..5f47d80ef4f 100644
--- a/src/mongo/db/s/operation_shard_version.cpp
+++ b/src/mongo/db/s/operation_shard_version.cpp
@@ -39,7 +39,7 @@ namespace {
 const OperationContext::Decoration<OperationShardVersion> shardingMetadataDecoration =
     OperationContext::declareDecoration<OperationShardVersion>();
 
-const char* kShardVersionField = "shardVersion";
+const char kShardVersionField[] = "shardVersion";
 const ChunkVersion kUnshardedVersion(ChunkVersion::UNSHARDED());
 
 }  // namespace mongo
@@ -50,26 +50,32 @@ OperationShardVersion& OperationShardVersion::get(OperationContext* txn) {
     return shardingMetadataDecoration(txn);
 }
 
+StringData OperationShardVersion::fieldName() {
+    return kShardVersionField;
+}
+
 void OperationShardVersion::initializeFromCommand(NamespaceString ns, const BSONObj& cmdObj) {
+    initializeFromCommand(std::move(ns), cmdObj[fieldName()]);
+}
+
+void OperationShardVersion::initializeFromCommand(NamespaceString ns,
+                                                  const BSONElement& shardVersionElt) {
     if (ns.isSystemDotIndexes()) {
         setShardVersion(std::move(ns), ChunkVersion::IGNORED());
         return;
     }
 
-    BSONElement versionElt;
-    Status status = bsonExtractTypedField(cmdObj, kShardVersionField, BSONType::Array, &versionElt);
-    if (!status.isOK()) {
+    if (shardVersionElt.eoo() || shardVersionElt.type() != BSONType::Array) {
         return;
     }
 
-    const BSONArray versionArr(versionElt.Obj());
+    const BSONArray versionArr(shardVersionElt.Obj());
     bool hasVersion = false;
     ChunkVersion newVersion = ChunkVersion::fromBSON(versionArr, &hasVersion);
 
     if (!hasVersion) {
         return;
     }
-
     setShardVersion(std::move(ns), std::move(newVersion));
 }
 
diff --git a/src/mongo/db/s/operation_shard_version.h b/src/mongo/db/s/operation_shard_version.h
index 33021dcdbae..1ec6e2bc1c1 100644
--- a/src/mongo/db/s/operation_shard_version.h
+++ b/src/mongo/db/s/operation_shard_version.h
@@ -53,6 +53,8 @@ public:
 
     OperationShardVersion();
 
+    static StringData fieldName();
+
     /**
      * Retrieves a reference to the shard version decorating the OperationContext, 'txn'.
      */
@@ -66,6 +68,7 @@ public:
      * Expects the format { ..., shardVersion: [<version>, <epoch>] }.
      */
     void initializeFromCommand(NamespaceString ns, const BSONObj& cmdObj);
+    void initializeFromCommand(NamespaceString ns, const BSONElement& shardVersionElement);
 
     /**
      * Returns whether or not there is a shard version associated with this operation.