PHP Multidimensional Array Searching (Find key by specific value)

Question

I have this multidimensional array. I need to search it and return only the key that matches the value of the "slug". I know there are other threads about searching multidimensional arrays, but I'm not really understanding enough to apply to my situation. Thanks very much for any help!

So I need a function like:

myfunction($products,'breville-one-touch-tea-maker-BTM800XL');
// returns 1

Here's the Array:

$products = array (
1  => array(
        'name'          => 'The Breville One-Touch Tea Maker',
        'slug'          => 'breville-one-touch-tea-maker-BTM800XL',
        'shortname'     => 'The One-Touch Tea Maker',
        'listprice'     => '299.99',
        'price'         => '249.99',
        'rating'        => '9.5',
        'reviews'       => '81',
        'buyurl'        => 'http://www.amazon.com/The-Breville-One-Touch-Tea-Maker/dp/B003LNOPSG',
        'videoref1'     => 'xNb-FOTJY1c',
        'videoref2'     => 'WAyk-O2B6F8',
        'image'         => '812BpgHhjBML.jpg',
        'related1'      => '2',
        'related2'      => '3',
        'related3'      => '4',
        'bestbuy'       => '1',
        'quote'         => '',
        'quoteautor'    => 'K. Martino',
        ),

2  => array(
        'name'          => 'Breville Variable-Temperature Kettle BKE820XL',
        'slug'          => 'breville-variable-temperature-kettle-BKE820XL',
        'shortname'     => 'Variable Temperature Kettle',
        'listprice'     => '199.99',
        'price'         => '129.99',
        'rating'        => '9',
        'reviews'       => '78',
        'buyurl'        => 'http://www.amazon.com/Breville-BKE820XL-Variable-Temperature-1-8-Liter-Kettle/dp/B001DYERBK',
        'videoref1'     => 'oyZWBD83xeE',
        'image'         => '41y2B8jSKmwL.jpg',
        'related1'      => '3',
        'related2'      => '4',
        'related3'      => '5',
        'bestbuy'       => '1',
        'quote'         => '',
        'quoteautor'    => '',
        ),
);

Answer 1

Another poossible solution is based on the array_search() function. You need to use PHP 5.5.0 or higher.

Example

$userdb=Array
(
(0) => Array
    (
        (uid) => '100',
        (name) => 'Sandra Shush',
        (url) => 'urlof100'
    ),

(1) => Array
    (
        (uid) => '5465',
        (name) => 'Stefanie Mcmohn',
        (pic_square) => 'urlof100'
    ),

(2) => Array
    (
        (uid) => '40489',
        (name) => 'Michael',
        (pic_square) => 'urlof40489'
    )
);

$key = array_search(40489, array_column($userdb, 'uid'));

echo ("The key is: ".$key);
//This will output- The key is: 2

Explanation

The function array_search() has two arguments. The first one is the value that you want to search. The second is where the function should search. The function array_column() gets the values of the elements which key is 'uid'.

Summary

So you could use it as:

array_search('breville-one-touch-tea-maker-BTM800XL', array_column($products, 'slug'));

or, if you prefer:

// define function
function array_search_multidim($array, $column, $key){
    return (array_search($key, array_column($array, $column)));
}

// use it
array_search_multidim($products, 'slug', 'breville-one-touch-tea-maker-BTM800XL');

The original example(by xfoxawy) can be found on the DOCS.
The array_column() page.

---

Update

Due to Vael comment I was curious, so I made a simple test to meassure the performance of the method that uses array_search and the method proposed on the accepted answer.

I created an array which contained 1000 arrays, the structure was like this (all data was randomized):

[
      {
            "_id": "57fe684fb22a07039b3f196c",
            "index": 0,
            "guid": "98dd3515-3f1e-4b89-8bb9-103b0d67e613",
            "isActive": true,
            "balance": "$2,372.04",
            "picture": "http://placehold.it/32x32",
            "age": 21,
            "eyeColor": "blue",
            "name": "Green",
            "company": "MIXERS"
      },...
]

I ran the search test 100 times searching for different values for the name field, and then I calculated the mean time in milliseconds. Here you can see an example.

Results were that the method proposed on this answer needed about 2E-7 to find the value, while the accepted answer method needed about 8E-7.

Like I said before both times are pretty aceptable for an application using an array with this size. If the size grows a lot, let's say 1M elements, then this little difference will be increased too.

Update II

I've added a test for the method based in array_walk_recursive which was mentionend on some of the answers here. The result got is the correct one. And if we focus on the performance, its a bit worse than the others examined on the test. In the test, you can see that is about 10 times slower than the method based on array_search. Again, this isn't a very relevant difference for the most of the applications.

Update III

Thanks to @mickmackusa for spotting several limitations on this method:

• This method will fail on associative keys.
• This method will only work on indexed subarrays (starting from 0 and have consecutively ascending keys).