Spot\Entity\Collection::toArray PHP Method

    public function toArray($keyColumn = null, $valueColumn = null)
    {
        // Both empty
        if (null === $keyColumn && null === $valueColumn) {
            $return = array();
            foreach ($this->_results as $row) {
                $return[] = $row->toArray();
            }
            // Key column name
        } elseif (null !== $keyColumn && null === $valueColumn) {
            $return = array();
            foreach ($this->_results as $row) {
                $return[] = $row->{$keyColumn};
            }
            // Both key and valud columns filled in
        } else {
            $return = array();
            foreach ($this->_results as $row) {
                $return[$row->{$keyColumn}] = $row->{$valueColumn};
            }
        }
        return $return;
    }

 /**
  * Set identity values from given collection
  *
  * @param \Spot\Entity\Collection
  */
 public function identityValuesFromCollection(Collection $collection)
 {
     $this->identityValue($collection->toArray($this->localKey()));
 }