DBAL-26 - Add strict null check

lib/Doctrine/DBAL/Types/DateTimeType.php

@@ -46,8 +46,8 @@ class DateTimeType extends Type
     
     public function convertToPHPValue($value, AbstractPlatform $platform)
     {
-        if (!$value) {
-            return $value;
+        if ($value === null) {
+            return null;
         }
 
         $val = \DateTime::createFromFormat($platform->getDateTimeFormatString(), $value);

lib/Doctrine/DBAL/Types/DateTimeTzType.php

@@ -66,8 +66,8 @@ class DateTimeTzType extends Type
 
     public function convertToPHPValue($value, AbstractPlatform $platform)
     {
-        if (!$value) {
-            return $value;
+        if ($value === null) {
+            return null;
         }
 
         $val = \DateTime::createFromFormat($platform->getDateTimeTzFormatString(), $value);

lib/Doctrine/DBAL/Types/DateType.php

@@ -46,8 +46,8 @@ class DateType extends Type
     
     public function convertToPHPValue($value, AbstractPlatform $platform)
     {
-        if (!$value) {
-            return $value;
+        if ($value === null) {
+            return null;
         }
 
         $val = \DateTime::createFromFormat('!'.$platform->getDateFormatString(), $value);

lib/Doctrine/DBAL/Types/TimeType.php

@@ -55,8 +55,8 @@ class TimeType extends Type
      */
     public function convertToPHPValue($value, AbstractPlatform $platform)
     {
-        if (!$value) {
-            return $value;
+        if ($value === null) {
+            return null;
         }
 
         $val = \DateTime::createFromFormat($platform->getTimeFormatString(), $value);