refactored auto increment

lib/model-factory.js

@@ -110,7 +110,7 @@ module.exports = (function() {
 
     // options is not a hash but an id
     if(typeof options == 'number')
-      options = {where: options}
+      options = { where: options }
     else if (Utils.argsArePrimaryKeys(arguments, this.primaryKeys)) {
         var where = {}
           , self  = this
@@ -120,7 +120,7 @@ module.exports = (function() {
           where[key] = arg
         })
 
-        options = {where: where}
+        options = { where: where }
     }
 
     options.limit = 1
@@ -228,16 +228,16 @@ module.exports = (function() {
   }
 
   var findAutoIncrementField = function() {
-    var self = this
+    var self   = this
+      , fields = this.QueryGenerator.findAutoIncrementField(this)
 
     this.autoIncrementField = null
-    Utils._.map(this.attributes, function(definition, name) {
-      if (definition && (definition.indexOf('auto_increment') > -1)) {
-        if (self.autoIncrementField)
-          throw new Error('Invalid model definition. Only one autoincrement field allowed.')
-        else
-          self.autoIncrementField = name
-      }
+
+    fields.forEach(function(field) {
+      if(self.autoIncrementField)
+        throw new Error('Invalid model definition. Only one autoincrement field allowed.')
+      else
+        self.autoIncrementField = field
     })
   }