wrapWith method in Model

model/model.js

@@ -404,6 +404,18 @@ steal.plugins('jquery/class', 'jquery/lang').then(function() {
 		 * @codeend
 		 */
 		defaults: {},
+		/**
+		 * WrapWith is used to decide wrap class for object. 
+		 * It is a convience method to avoid unnecessary overwriting 
+		 * Wrap method. It enables simpler implementation of system
+		 * similar to Rails STI (single table inheritance).
+		 * 
+		 * @param {Object} attributes
+		 * @return {Class} a class that will wrap the object
+		 */
+		wrapWith: function( attributes ) {
+			return this;
+		},
 		/**
 		 * Wrap is used to create a new instance from data returned from the server.
 		 * It is very similar to doing <code> new Model(attributes) </code> 
@@ -424,9 +436,11 @@ steal.plugins('jquery/class', 'jquery/lang').then(function() {
 			if (!attributes ) {
 				return null;
 			}
-			return new this(
 			// checks for properties in an object (like rails 2.0 gives);
-			attributes[this.singularName] || attributes.data || attributes.attributes || attributes);
+			var attrs = attributes[this.singularName] || attributes.data || attributes.attributes || attributes;
+			// grab the wrapper class and wrap the attributes
+			var wrapper = this.wrapWith(attrs);
+			return new wrapper(attrs);
 		},
 		/**
 		 * Takes raw data from the server, and returns an array of model instances.

model/test/qunit/model_test.js

@@ -22,6 +22,31 @@ module("jquery/model", {
 				return "Mr. "+this.name;
 			}
 		})
+
+		$.Model.extend("Animal",{
+		wrapWith: function( attrs ) {
+			if(attrs.animal_type == 'dog') return Dog;
+			if(attrs.animal_type == 'cat') return Cat;
+			return this;
+		} 
+	},{
+		animal: function() {
+			return 'animal';
+		}
+	});
+
+		Animal.extend("Dog",{},{
+			animal: function() {
+				return 'dog';
+			}
+		});
+		Animal.extend("Cat",{},{
+			animal: function() {
+				return 'cat';
+			}
+		});
+
+
 	}
 })
 
@@ -141,3 +166,12 @@ test("isNew", function(){
 	var p3 = new Person({id: 0})
 	ok(!p3.isNew(), "0 is not new");
 })
+
+test("wrapWith", function(){
+	var dog = Animal.wrap({animal_type: 'dog', name: 'Rex'});
+	var cat = Animal.wrap({animal_type: 'cat', name: 'Garfield'});
+	var mouse = Animal.wrap({animal_type: 'mouse', name: 'Jerry'});
+	equals(dog.animal(), 'dog', 'call correct animal method from dog subclass');
+	equals(cat.animal(), 'cat', 'call correct animal method from cat subclass');
+	equals(mouse.animal(), 'animal', 'call correct animal method from base Animal class');
+})