add validation for date interval

Entity/SingleTask.php

@@ -28,10 +28,16 @@ class SingleTask extends AbstractTask
      *
      * @ORM\Column(name="start_date", type="date", nullable=true)
      * @Assert\Date()
+     * 
      * @Assert\Expression(
-     *  "value === null or value < this.getEndDate()",
+     *  "value === null or this.getEndDate() === null or value < this.getEndDate()",
      *  message="The start date must be before the end date"
      * )
+     * 
+     * @Assert\Expression(
+     *  "value === null or this.getWarningDate() === null or this.getWarningDate() > this.getStartDate()",
+     *  message="The start date must be before warning date"
+     * )
      */
     private $startDate;
 
@@ -45,8 +51,16 @@ class SingleTask extends AbstractTask
 
     /**
      * @var \DateInterval
+     *  and this.getEndDate() === null
      *
      * @ORM\Column(name="warning_interval", type="dateinterval", nullable=true)
+     * 
+     * @Assert\Expression(
+     *  "!(value != null and this.getEndDate() == null)",
+     *  message="An end date is required if a warning interval is set"
+     * )
+     * 
+     * 
      */
     private $warningInterval;
     
@@ -65,7 +79,8 @@ class SingleTask extends AbstractTask
      * @var \Doctrine\Common\Collections\Collection
      * @ORM\OneToMany(
      *  targetEntity="\Chill\TaskBundle\Entity\Task\SingleTaskPlaceEvent",
-     *  mappedBy="task"
+     *  mappedBy="task",
+     *  cascade={ "remove" }
      * )
      */
     private $taskPlaceEvents;