custom validators yield an Error instance and error args are transported as is

lib/dao-validator.js

@@ -10,6 +10,9 @@ var DaoValidator = module.exports = function(model, options) {
   this.options = options
 }
 
+/** @define {string} The error key for arguments as passed by custom validators */
+DaoValidator.RAW_KEY_NAME = '__raw'
+
 DaoValidator.prototype.validate = function() {
   var self = this
 
@@ -24,13 +27,16 @@ DaoValidator.prototype.validate = function() {
         emitter.emit('success')
       })
       .error(function(err) {
-        var errors = {}
+	var error = new Error('Validation error')
+	error[DaoValidator.RAW_KEY_NAME] = []
 
         Utils._.each(err, function (value) {
-          Utils._.extend(errors, value)
+	  error[DaoValidator.RAW_KEY_NAME].push(value[DaoValidator.RAW_KEY_NAME])
+	  delete value[DaoValidator.RAW_KEY_NAME]
+	  Utils._.extend(error, value)
         })
 
-        emitter.emit('success', errors)
+	emitter.emit('success', error)
       })
   }).run()
 }
@@ -72,8 +78,11 @@ var validateModel = function() {
       var next = function(err) {
 
         if (err) {
-          var error = {}
-          error[validatorType] = [err]
+	  var error = {};
+	  error[DaoValidator.RAW_KEY_NAME] = err;
+
+	  var msg = ((err instanceof Error) ? err.message : err)
+	  error[validatorType] = [msg]
           emitter.emit('error', error)
         } else {
           emitter.emit('success')
@@ -155,7 +164,7 @@ var prepareValidationOfAttribute = function(value, details, validatorType, optio
       try {
         details.apply(this.model, callArgs)
       } catch(ex) {
-        return next(ex.message)
+	return next(ex)
       }
 
       if (!isAsync) {