PHP Array inventory editing - php

Question

I am working with a system where inventory is stored in a single database table. I need help to find the best way to add/remove items from this.
It is stored as follows;
3:1|8:2|5:3|4:4
the first number represents quantity and the second number is the item ID. The Pipe | splits these items.
So 3:1 = quantity 3 of item 1.
I am trying to use PHP to look at this string, find if the item is there. If it is add to or remove from it. OR if the item isn't there then create it.
I know I would have to use an array to achieve this but I'm a little lost at how this would be done, any help with this would be greatly appreciated.
Thanks.

Answer 1

I would make a small class that holds an item -> quantity map (stored as an array) that is created from that string, and builds the string back when requested.
This makes use of:
explode to split the string parts,
implode combined with array_map to join them back.
Code:
class DataStructure
{
private $data = [];
public function __construct(string $data)
{
foreach (explode('|', $data) as $item_quantity) {
list($quantity, $item) = explode(':', $item_quantity);
$this->data[$item] = (int)$quantity;
}
}
public function getItemQuantity(int $item): ?int
{
return $this->data[$item] ?? null;
}
public function setItemQuantity(int $item, int $quantity)
{
$this->data[$item] = $quantity;
}
public function __toString(): string
{
return implode('|', array_map(function ($item) {
return $this->data[$item] . ':' . $item;
}, array_keys($this->data)));
}
}
Note that this doesn't include error handling, for the purpose of this example.
Demo: https://3v4l.org/pqRQh
Demo (PHP 5.6 compatible): https://3v4l.org/tK9Q9