修复datepicker datetimepicker空值问题

vendor/blobt/widgets/DatePicker.php

@@ -133,8 +133,10 @@ SCRIPT;
 
         if ($this->hasModel()) {
             $timestamp = ArrayHelper::getValue($this->model, $this->attribute);
+            if (!empty($timestamp)) {
                 $value = date($this->format, $timestamp);
             }
+        }
 
         if (empty($timestamp) && $this->autoFill) {
             $timestamp = time();

vendor/blobt/widgets/DatetimePicker.php

@@ -133,8 +133,10 @@ SCRIPT;
 
         if ($this->hasModel()) {
             $timestamp = ArrayHelper::getValue($this->model, $this->attribute);
+            if (!empty($timestamp)) {
                 $value = date($this->format, $timestamp);
             }
+        }
 
         if (empty($timestamp) && $this->autoFill) {
             $timestamp = time();