datepicker should show empty field when value is empty string

extensions/jui/CHANGELOG.md

@@ -5,6 +5,7 @@ Yii Framework 2 jui extension Change Log
 -----------------------
 
 - Enh #6570: Datepicker now uses fallback to find language files, e.g. application language is `de-DE` and the translation files does not exists, it will use `de` instead (cebe)
+- Enh #6471: Datepicker will now show an empty field when value is an empty string (cebe)
 
 
 2.0.1 December 07, 2014

extensions/jui/DatePicker.php

@@ -169,7 +169,7 @@ class DatePicker extends InputWidget
         } else {
             $value = $this->value;
         }
-        if ($value !== null) {
+        if ($value !== null && $value !== '') {
             // format value according to dateFormat
             try {
                 $value = Yii::$app->formatter->asDate($value, $this->dateFormat);