Add pluck method that takes an attribute name and returns an array of…

… values.

CHANGELOG.markdown

@@ -1,5 +1,6 @@
 # Changelog
 
+* Add `pluck` method that takes an attribute name and returns an array of values.
 * Fix for callbacks being wrongly called on multiple instances - they were being stored on the prototype and thus being shared across instances. Thanks to Oliver Nightingale for identifying the bug and writing a test case.
 
 ## 0.8.4

src/model_class_methods.js

@@ -60,6 +60,17 @@ Model.ClassMethods = {
     return all[all.length - 1] || null;
   },
 
+  pluck: function(attribute) {
+    var all = this.all()
+    var plucked = []
+
+    for (var i = 0; i < all.length; i++) {
+      plucked.push(all[i].attr(attribute))
+    }
+
+    return plucked
+  },
+
   remove: function(id) {
     var ids = _.invoke(this.collection, 'id');
     var index = _.indexOf(ids, id);

test/public/tests/model_class_methods.js

@@ -141,6 +141,20 @@ test("each (and chaining)", function() {
   same(titles, ["Bar", "Baz"]);
 });
 
+test(".pluck", function() {
+  var Post = Model('post')
+
+  var post1 = new Post({ id: 1, title: "a" })
+  var post2 = new Post({ id: 2, title: "b" })
+  var post3 = new Post({ id: 3, title: "c" })
+  var post4 = new Post({ id: 4, title: "d" })
+
+  Post.add(post1, post2, post3, post4)
+
+  same(Post.pluck("id"), [1, 2, 3, 4])
+  same(Post.pluck("title"), ["a", "b", "c", "d"])
+})
+
 test("sort (and chaining)", function() {
   var Post = Model('post');