Fix the model attachment to data source

lib/datasource.js

@@ -548,26 +548,23 @@ DataSource.prototype.getModelDefinition = function(name) {
 DataSource.prototype.attach = function (modelClass) {
   if(modelClass.dataSource === this) {
     // Already attached to the data source
-    return;
+    return modelClass;
+  }
+
+  if(modelClass.modelBuilder !== this.modelBuilder) {
+    this.modelBuilder.definitions[modelClass.modelName] = modelClass.definition;
+    this.modelBuilder.models[modelClass.modelName] = modelClass;
+    // reset the modelBuilder
+    modelClass.modelBuilder = this.modelBuilder;
   }
-  var className = modelClass.modelName;
-  var modelDef = modelClass.modelBuilder.getModelDefinition(className);
-  var properties = modelDef.properties;
-  var settings = modelDef.settings;
 
   // redefine the dataSource
   modelClass.dataSource = this;
-  // add to def
-  var def = new ModelDefinition(this.modelBuilder, className, properties, settings);
-  def.build();
-  this.modelBuilder.definitions[className] = def;
-  this.modelBuilder.models[className] = modelClass;
-
-  this.setupDataAccess(modelClass, settings);
 
+  this.setupDataAccess(modelClass, modelClass.settings);
   modelClass.emit('dataSourceAttached', modelClass);
+  return modelClass;
 
-  return this;
 };
 
 /**