add validation to single task controller::new

Entity/SingleTask.php

@@ -3,6 +3,7 @@
 namespace Chill\TaskBundle\Entity;
 
 use Doctrine\ORM\Mapping as ORM;
+use Symfony\Component\Validator\Constraints as Assert;
 
 /**
  * SingleTask
@@ -25,6 +26,11 @@ class SingleTask extends AbstractTask
      * @var \DateTime
      *
      * @ORM\Column(name="start_date", type="date", nullable=true)
+     * @Assert\Date()
+     * @Assert\Expression(
+     *  "value === null or value < this.getEndDate()",
+     *  message="The start date must be before the end date"
+     * )
      */
     private $startDate;
 
@@ -32,6 +38,7 @@ class SingleTask extends AbstractTask
      * @var \DateTime
      *
      * @ORM\Column(name="end_date", type="date", nullable=true)
+     * @Assert\Date()
      */
     private $endDate;