Get last element in Collection

Question

I'm trying to get a property on the last element in a collection. I tried

end($collection)->getProperty()

and

$collection->last()->getProperty()

none works

(tells me I'm trying to use getProperty() on a boolean).

/**
 * Get legs
 *
 * @return \Doctrine\Common\Collections\Collection
 */
public function getLegs()
{
    return $this->aLegs;
}

public function getLastlegdate()
{
    $legs = $this->aLegs;

    return $legs->last()->getStartDate();
}

Any idea why ?

Are you sure `$collection` has items in it? `end()` will return `false` on an empty array. — aquemini, Sep 10 '15 at 16:15
Please provide some code to help us understand better assist you — Erick, Sep 10 '15 at 16:18

score 16 · Accepted Answer · answered Sep 10 '15 at 16:49

The problem you have is due because the collection is empty. Internally the last() method use the end() php function that from the doc:

Returns the value of the last element or FALSE for empty array.

So change your code as follow:

$property = null

if (!$collection->isEmpty())
{
$property =  $collection->last()->getProperty();
}

hope this help

score 0 · Answer 2 · answered Jun 19 '19 at 08:19

This $collection->last()->getProperty() is breaking the law of Demeter. The function should have a single responsibility. Try this.

/**
 * @return Leg|null
 */
public function getLastLeg(): ?Leg
{
   $lastLeg = null;
   if (!$this->aLegs->isEmpty()) {
     $lastLeg = $this->aLegs->last();
   }
   return $lastLeg;
}

/**
 * @return \DateTime|null
 */
 public function getLastLegDate(): ?\DateTime
 {
   $lastLegDate = null;
   $lastLeg = $this->getLastLeg();
   if ($lastLeg instanceOf Leg) {
     $lastLeg->getStartDate();
   }

   return $lastLegDate;
 }

Get last element in Collection

2 Answers2