Fixes #4519: `yii\base\Model::isAttributeRequired()` should check if the `when`…

framework/CHANGELOG.md

@@ -76,6 +76,7 @@ Yii Framework 2 Change Log
 - Bug #4469: Make `Security::compareString()` timing depend only on length of `$actual` input and add unit test. (tom--)
 - Bug #4470: Avoid endless loop when exporting logs with low values of flushInterval and eportInterval (cebe)
 - Bug #4514: Fixed Request class crashing when empty CSRF token value is sent in cookie (cebe)
+- Bug #4519: `yii\base\Model::isAttributeRequired()` should check if the `when` option of the validator is set (thiagotalma)
 - Bug: Fixed inconsistent return of `\yii\console\Application::runAction()` (samdark)
 - Bug: URL encoding for the route parameter added to `\yii\web\UrlManager` (klimov-paul)
 - Bug: Fixed the bug that requesting protected or private action methods would cause 500 error instead of 404 (qiangxue)

framework/base/Model.php

@@ -442,7 +442,7 @@ class Model extends Component implements IteratorAggregate, ArrayAccess, Arrayab
     public function isAttributeRequired($attribute)
     {
         foreach ($this->getActiveValidators($attribute) as $validator) {
-            if ($validator instanceof RequiredValidator && !$validator->when) {
+            if ($validator instanceof RequiredValidator && $validator->when === null) {
                 return true;
             }
         }