Fix defaultValues getting overwritten

changelog.md

+# Future
+- [FIXED] Fix defaultValues getting overwritten on build
+
 # 3.21.0
 - [FIXED] Confirmed that values modified in validation hooks are preserved [#3534](https://github.com/sequelize/sequelize/issues/3534)
 - [FIXED] Support lower case type names in SQLite [#5482](https://github.com/sequelize/sequelize/issues/5482)

lib/instance.js

@@ -22,10 +22,9 @@ var initValues = function(values, options) {
     defaults = {};
 
     if (this.Model._hasDefaultValues) {
-      Utils._.each(this.Model._defaultValues, function(valueFn, key) {
-        if (defaults[key] === undefined) {
-          defaults[key] = valueFn();
-        }
+      defaults = _.mapValues(this.Model._defaultValues, function(valueFn) {
+        var value = valueFn();
+        return (value && value._isSequelizeMethod) ? value : _.cloneDeep(value);
       });
     }
 

test/unit/instance/build.test.js

@@ -94,5 +94,21 @@ describe(Support.getTestDialectTeaser('Instance'), function() {
       expect(instance.get('number2')).not.to.be.undefined;
       expect(instance.get('number2')).to.equal(2);
     });
+
+    it('should clone the default values', function () {
+      var Model = current.define('Model', {
+        data: {
+          type: DataTypes.JSONB,
+          defaultValue: { foo: 'bar' }
+        }
+      })
+        , instance;
+
+      instance = Model.build();
+      instance.data.foo = 'biz';
+
+      expect(instance.get('data')).to.eql({ foo: 'biz' });
+      expect(Model.build().get('data')).to.eql({ foo: 'bar' });
+    });
   });
 });