Error if user already exists, clean user

utils/model.js

@@ -245,6 +245,25 @@ module.exports.createClass = function(model) {
         }
     }
 
+    ret.prototype.toJSON = function() {
+        let json = {};
+        for (let field of model.fields) {
+            json[field.name] = this[field.name]
+        }
+        return json;
+    }
+
+    ret.fromJSON = function(json) {
+        let result = new ret();
+
+        for (let field of model.fields) {
+            result[field.name] = json[field.name];
+        }
+        result._persisted = false;
+
+        return result;
+    }
+
     ret.prototype.save = function(callback = () => {}) {
         let fieldsToSave = [];
         for (let field of model.fields) {