Php get specific array in a multidimensional array

Question

I'm looking for a solution to get an array from a multidimensional array

For example; This is my array:

I'd like to get the array where the id equals 1

So in this example, where [id] => 1 I would like to capture the entire array of id 1, thus:

Array
                (
                    [0] => Array
                        (
                            [id] => 1
                            [name] => Erwin Dubois
                            [text] => Erwin Dubois
                            [parent_id] => 2
                            [href] => http://google.com
                            [nodes] => Array
                                (
                                    [0] => Array
                                        (
                                            [id] => 3
                                            [name] => Test Gebruiker
                                            [text] => Test Gebruiker
                                            [parent_id] => 1
                                            [href] => http://google.com
                                        )

                                    [1] => Array
                                        (
                                            [id] => 4
                                            [name] => Catharina
                                            [text] => Catharina
                                            [parent_id] => 1
                                            [href] => http://google.com
                                        )

                                )

                        )

Is there a way in php where I can have a function like;

function get_subarray($id) {
  // Select array where id = $id
}

Any point towards the direction is greatly appreciated! It would be needed into a function since I would parse different userlevels depending on their unique id

array:

$json = file_get_contents("https://innerbeauthe.be/cp/_data/fetch.php");
$data = json_decode($json,true);

Is there guaranteed to be only one of any given id?

Michael Berkowski
– Michael Berkowski

2021-02-08 03:19:45 +00:00
Commented Feb 8, 2021 at 3:19 — Michael Berkowski
– Michael Berkowski, Commented Feb 8, 2021 at 3:19
Yes, the id is a unique identifier (PK, UQ)

Erwin Dubois
– Erwin Dubois

2021-02-08 11:11:29 +00:00
Commented Feb 8, 2021 at 11:11 — Erwin Dubois
– Erwin Dubois, Commented Feb 8, 2021 at 11:11

Michael Berkowski · Accepted Answer · 2021-02-08 15:22:54Z

1

You can define a recursive function which traverses the array in search of the desired array key.

Although PHP includes a function array_walk_recursive(), it will traverse into leaf nodes and makes it difficult to return a parent array. Likewise, using RecursiveArrayIterator actually complicates getting at the array you want instead of the leaf notes. Instead it is not too complicated to create your own:

// Function accepts an array and a search value
function walk_for_array(array $a, $search) {
  // Loop over the array
  foreach ($a as $k => $v) {
    // Find sub-arrays (rather than scalar values)
    if (is_array($v)) {
      // Check if there is an 'id' key and if it matches your search value
      if (isset($v['id']) && $v['id'] == $search) {                                                                                           
        // return it
        return $v; 
      }   
      else {
        // Otherwise continue drilling into the array for more arrays
        $sub = walk_for_array($v, $search);
        // Return the recursive value only if the inner call
        // was non-null
        if ($sub) return $sub;
      }   
    }   
  }
}

// Call it, searching for id == 1
$found = walk_for_array($your_big_array, 1);

print_r($found);

// Call it, searching for id == 13
$found = walk_for_array($your_big_array, 13);

print_r($found);

Prints:

Array
(
    [id] => 1
    [name] => Erwin Dubois
    [text] => Erwin Dubois
    [parent_id] => 2
    [href] => http://google.com
    [nodes] => Array
        (
            [0] => Array
                (
                    [id] => 3
                    [name] => Test Gebruiker
                    [text] => Test Gebruiker
                    [parent_id] => 1
                    [href] => http://google.com
                )

            [1] => Array
                (
                    [id] => 4
                    [name] => Catharina
                    [text] => Catharina
                    [parent_id] => 1
                    [href] => http://google.com
                )

        )

)

And for id = 13

Array
(
    [id] => 13
    [name] => Macy VanMaele
    [text] => Macy VanMaele
    [parent_id] => 6
    [href] => http://google.com
)

edited Feb 8, 2021 at 15:22

answered Feb 8, 2021 at 3:57

Michael Berkowski

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5 Comments

Erwin Dubois Over a year ago

Hello Michael, Thank you for your response, I tried the function you posted and it worked for the following id's: 1 & 2; If for example, I would select Id = 5, I get no results at all, tried to break down the function in printable arrays but don't see why it doesn't load the id 5 nor the others (3 for example)

Michael Berkowski Over a year ago

I will have some time to look at it in a couple of hours.

Michael Berkowski Over a year ago

@ErwinDubois Okay I think it's working correctly now - the recursive array call was passing through its return even if null. That is fixed to continue searching until the inner call returns a non-null

Erwin Dubois Over a year ago

Thank you! It works like a charm, you saved me hours of head scratching, eye frowning, table-bashing arguements with myselve! haha. Greatly appreciated, also I love the fact that you commented out the function, gives me the time to see the logic in it.

Michael Berkowski Over a year ago

You're welcome. With regard to commenting the function, if someone posts an answer for to your question without good explanation, please don't be afraid to ask them for an explanation with a comment. While I have certainly encountered individuals here who bristle at that, the explanations are much more valuable to future searchers who find the answer.

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Php get specific array in a multidimensional array

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