datastore: support overriding namespace.

lib/common/util.js

@@ -163,3 +163,55 @@ function handleResp(err, resp, body, callback) {
 }
 
 module.exports.handleResp = handleResp;
+
+/**
+ * Get the type of a value.
+ *
+ * @private
+ *
+ * @return {string}
+ */
+function getType(value) {
+  return Object.prototype.toString.call(value).match(/\s(\w+)\]/)[1];
+}
+
+/**
+ * Check if an object is of the given type.
+ *
+ * @param {*} value - Value to compare to.
+ * @param {string} type - Type to check against object's value.
+ * @return {boolean}
+ *
+ * @example
+ * ```js
+ * is([1, 2, 3], 'array');
+ * // true
+ * ```
+ */
+function is(value, type) {
+  return getType(value).toLowerCase() === type.toLowerCase();
+}
+
+module.exports.is = is;
+
+/**
+ * Convert an object into an array.
+ *
+ * @param {object} object - Object to convert to an array.
+ * @return {array}
+ *
+ * @example
+ * ```js
+ * function aFunction() {
+ *   return toArray(arguments);
+ * }
+ *
+ * aFunction(1, 2, 3);
+ * // [1, 2, 3]
+ * ```
+ */
+function toArray(object) {
+  return [].slice.call(object);
+}
+
+module.exports.toArray = toArray;

lib/datastore/dataset.js

@@ -82,18 +82,32 @@ function Dataset(options) {
 }
 
 /**
- * Helper to create a Key object, scoped to the namespace if present.
+ * Helper to create a Key object, scoped to the dataset's namespace by default.
+ *
+ * You may also specify a configuration object to define a namespace and path.
  *
  * @example
  * ```js
- * var key = dataset.key('Company', 123);
+ * var key;
+ *
+ * // Create a key from the dataset's namespace.
+ * key = dataset.key('Company', 123);
+ *
+ * // Create a key from a provided namespace and path.
+ * key = dataset.key({
+ *   namespace: 'My-NS',
+ *   path: ['Company', 123]
+ * });
  * ```
  */
-Dataset.prototype.key = function() {
-  return new entity.Key({
-    namespace: this.ns,
-    path: [].slice.call(arguments)
-  });
+Dataset.prototype.key = function(keyConfig) {
+  if (!util.is(keyConfig, 'object')) {
+    keyConfig = {
+      namespace: this.ns,
+      path: util.toArray(arguments)
+    };
+  }
+  return new entity.Key(keyConfig);
 };
 
 

lib/datastore/entity.js

@@ -100,12 +100,7 @@ var SIGN_TO_ORDER = {
  */
 function Key(options) {
   this.namespace_ = options.namespace;
-
-  if (options.path.length > 1) {
-    this.path_ = [].slice.call(options.path);
-  } else {
-    this.path_ = options.path[0];
-  }
+  this.path_ = options.path;
 }
 
 module.exports.Key = Key;

test/datastore/dataset.js

@@ -29,6 +29,17 @@ describe('Dataset', function() {
     var ds = new datastore.Dataset({ projectId: 'test', namespace: 'my-ns' });
     var key = ds.key('Company', 1);
     assert.equal(key.namespace_, 'my-ns');
+    assert.deepEqual(key.path_, ['Company', 1]);
+  });
+
+  it('should allow namespace specification when creating a key', function() {
+    var ds = new datastore.Dataset({ projectId: 'test' });
+    var key = ds.key({
+      namespace: 'custom-ns',
+      path: ['Company', 1]
+    });
+    assert.equal(key.namespace_, 'custom-ns');
+    assert.deepEqual(key.path_, ['Company', 1])
   });
 
   it('should get by key', function(done) {