How to Sort after position a product collection?

Question

This is how I get my collection:

$_productCollection = $this->getItemCollection();

This is how I get the products:

foreach ($_productCollection as $_product):
     echo $_product->getData('position');
endforeach

At the moment I get my products randomly. Can I sort by position ? if yes how can i do it ? thx

This is the getItemCollection function from CORE:

public function getItemCollection()
    {
        if (is_null($this->_items)) {
            $behavior   = $this->getPositionBehavior();

            $this->_customItems = array();
            $this->_items = array();

            if (in_array($behavior, $this->getRuleBasedBehaviorPositions())) {
                $this->_items = $this->_getTargetRuleProducts();
            }
            if (in_array($behavior, $this->getSelectedBehaviorPositions())) {
                foreach ($this->_getLinkProducts() as $id => $item) {
                    $this->_customItems[$id] = $item;
                }
            }
            $this->_orderProductItems();
        }

        return $this->_items;
    }

Answer 1

Not possible, because this method does not return a collection (bad naming choice...). Instead it loads the collection immediately and returns an array with the results.

The simplest solution is to sort this array, using PHP:

usort($_productCollection, function($a, $b) {
    if ($a['position'] < $b['position]) {
        return -1;
    } elseif ($a['position'] > $b['position']) {
        return 1;
    }
    return 0;
});

or if you are using PHP 7:

usort($_productCollection, function($a, $b) {
    return $a['position'] <=> $b['position'];
});

Answer 2

Ok so you're talking about sorting and not filtering.

To do so you can use the setOrder method:

$_productCollection->getSelect()->order('position DESC');