up vote 0 down vote favorite

I have two arrays of products, both formatted exactly the same, like so:

$products = array(
    [0] => array(
        ['product_id'] => 33
        ['variation_id'] => 0
        ['product_price'] => 500.00
    ),
    [1] => array(
        ['product_id'] => 48
        ['variation_id'] => 0
        ['product_price'] => 600.00
    ),
)

I would like to be able to return a list of only those products not found in the second array, based on the product ID.

I only care about those NOT found in the second array, not additional ones added to the first, so array_diff won't seem to do the trick.

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what is the functional difference between additional ones added to the first and those not found in the second? are either of the posted solutions doing what you want, or are you looking for something else? – user410344 Aug 17 at 19:33

2 Answers

up vote 1 down vote accepted

A simple foreach loop should be enough:

<?php
$products = array(
    0 => array(
        'product_id' => 33,
        'variation_id' => 0,
        'product_price' => 500.00
    ),
    1 => array(
        'product_id' => 48,
        'variation_id' => 0,
        'product_price' => 600.00
    )
);

$products2 = array(
    1 => array(
        'product_id' => 48,
        'variation_id' => 0,
        'product_price' => 600.00
    ),
    2 => array(
        'product_id' => 49,
        'variation_id' => 0,
        'product_price' => 600.00
    )
);

$diff = array();

// Loop through all elements of the first array
foreach($products2 as $value)
{
  // Loop through all elements of the second loop
  // If any matches to the current element are found,
  // they skip that element
  foreach($products as $value2)
  {
    if($value['product_id'] == $value2['product_id'])
    continue 2;
  }
  // If no matches were found, append it to $diff
  $diff[] = $value;
}

The $diff array would then only hold the following value:

array (
  0 => 
  array (
    'product_id' => 49,
    'variation_id' => 0,
    'product_price' => 600,
  ),
)

Hope this helped!

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up vote 5 down vote

I suspect you want something like array_udiff. This lets you specify how to compare the two arrays, using a callback function. You just create a callback that compares based on product id's.

I think this satisfies what you want because the array_diff family of functions only compare the first array to the rest, it does not return elements that array2 (or 3, or 4) have that array1 does not.

<?php
$products = array(
    0 => array(
        'product_id' => 33,
        'variation_id' => 0,
        'product_price' => 500.00
    ),
    1 => array(
        'product_id' => 48,
        'variation_id' => 0,
        'product_price' => 600.00
    )
);

$products2 = array(
    1 => array(
        'product_id' => 48,
        'variation_id' => 0,
        'product_price' => 600.00
    ),
    2 => array(
        'product_id' => 49,
        'variation_id' => 0,
        'product_price' => 600.00
    )
);

function compare_ids($a, $b)
{
  return $b['product_id'] - $a['product_id'];
}

var_dump(array_udiff($products, $products2, "compare_ids"));
?>

Outputs:

array(1) {
  [0]=>
  array(3) {
    ["product_id"]=>
    int(33)
    ["variation_id"]=>
    int(0)
    ["product_price"]=>
    float(500)
  }
}
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