Fixes phalcon#12688

CHANGELOG.md

@@ -14,7 +14,8 @@
 - Fixed `Phalcon\Mvc\Model::getChangedFields` to correct detect changes from NULL to Zero [#12628](https://github.com/phalcon/cphalcon/issues/12628)
 - Fixed `Phalcon\Mvc\Model` to create/refresh snapshot after create/update/refresh operation [#11007](https://github.com/phalcon/cphalcon/issues/11007), [#11818](https://github.com/phalcon/cphalcon/issues/11818), [#11424](https://github.com/phalcon/cphalcon/issues/11424)
 - Fixed `Phalcon\Mvc\Model::validate` to correctly set code message [#12645](https://github.com/phalcon/cphalcon/issues/12645)
-- Added the value of the object intanceof Interface to `Phalcon\AcMl\Adapter\Memory`
+- Added the value of the object intanceof Interface to `Phalcon\Acl\Adapter\Memory`
+- Fixed `Phalcon\Mvc\Model` to correctly add error when try to save empty string value to not null and not default column [#12688](https://github.com/phalcon/cphalcon/issues/12688)
 
 # [3.0.4](https://github.com/phalcon/cphalcon/releases/tag/v3.0.4) (2017-02-20)
 - Fixed Isnull check is not correct when the model field defaults to an empty string. [#12507](https://github.com/phalcon/cphalcon/issues/12507)

phalcon/mvc/model.zep

@@ -2091,7 +2091,7 @@ abstract class Model implements EntityInterface, ModelInterface, ResultInterface
 											let isNull = true;
 										}
 									} else {
-										if value === null || (value === "" && value !== defaultValues[field]) {
+										if value === null || (value === "" && (!isset defaultValues[field] || value !== defaultValues[field])) {
 											let isNull = true;
 										}
 									}

tests/unit/Mvc/ModelTest.php

@@ -2,6 +2,7 @@
 
 namespace Phalcon\Test\Unit\Mvc;
 
+use DateTime;
 use Helper\ModelTrait;
 use Phalcon\Mvc\Model\Message;
 use Phalcon\Test\Models\Users;
@@ -646,4 +647,28 @@ function () {
             }
         );
     }
+
+    /**
+     * Tests empty string value on not null
+     *
+     * @issue  12688
+     * @author Wojciech Ślawski <[email protected]>
+     * @since  2017-03-09
+     */
+    public function testIssue12688()
+    {
+        $this->specify(
+            'Issue 12688 is happening',
+            function () {
+                $robots = new Robots();
+                $robots->name = '';
+                $robots->save(
+                    [
+                        'datetime' => (new DateTime())->format('Y-m-d'),
+                        'text'     => 'text',
+                    ]
+                );
+            }
+        );
+    }
 }