Cast key to string in hashCode function for KeyedPartitioner (#870)

lib/partitioner.js

@@ -3,9 +3,9 @@
 var util = require('util');
 var _ = require('lodash');
 
-var Partitioner = function () {};
+var Partitioner = function () { };
 
-var DefaultPartitioner = function () {};
+var DefaultPartitioner = function () { };
 util.inherits(DefaultPartitioner, Partitioner);
 
 DefaultPartitioner.prototype.getPartition = function (partitions) {
@@ -23,27 +23,29 @@ util.inherits(CyclicPartitioner, Partitioner);
 
 CyclicPartitioner.prototype.getPartition = function (partitions) {
   if (_.isEmpty(partitions)) return 0;
-  return partitions[ this.c++ % partitions.length ];
+  return partitions[this.c++ % partitions.length];
 };
 
-var RandomPartitioner = function () {};
+var RandomPartitioner = function () { };
 util.inherits(RandomPartitioner, Partitioner);
 
 RandomPartitioner.prototype.getPartition = function (partitions) {
   return partitions[Math.floor(Math.random() * partitions.length)];
 };
 
-var KeyedPartitioner = function () {};
+var KeyedPartitioner = function () { };
 util.inherits(KeyedPartitioner, Partitioner);
 
 // Taken from oid package (Dan Bornstein)
 // Copyright The Obvious Corporation.
 KeyedPartitioner.prototype.hashCode = function (string) {
   var hash = 0;
-  var length = string.length;
+  if (string) {
+    var length = string.toString().length;
 
-  for (var i = 0; i < length; i++) {
-    hash = ((hash * 31) + string.charCodeAt(i)) & 0x7fffffff;
+    for (var i = 0; i < length; i++) {
+      hash = ((hash * 31) + string.charCodeAt(i)) & 0x7fffffff;
+    }
   }
 
   return (hash === 0) ? 1 : hash;