Search a multidimensional array by key in PHP

Question

I have a question about filtering a multidimensional array in PHP. What i would like to achieve is to pull a specific array element (the value of mediacontent) from an existing array. This is what i got so far:

Existing multidimensional array:

$multidimensional_array = array(
 'entry' => array(
 0 => array(
 'width' => array(
 '$t' => '1536'
 ),
 'height' => array(
 '$t' => '2048'
 ),
 'id' => array(
 '$t' => '878974'
 ),
 'mediagroup' => array(
 'mediacontent' => array(
 'url' => 'http://website/urltotheobject.png',
 'width' => 384,
 'medium' => 'image',
 'type' => 'image/jpeg',
 'height' => 512
 )
 )
 ),
 1 => array(
 'width' => array(
 '$t' => '5486'
 ),
 'height' => array(
 '$t' => '1144'
 ),
 'id' => array(
 '$t' => '485435'
 ),
 'mediagroup' => array(
 'mediacontent' => array(
 'url' => 'http://website/urltotheobject.png',
 'width' => 512,
 'medium' => 'image',
 'type' => 'image/jpeg',
 'height' => 384
 )
 ) 
 )
 )
);

A (not properly working) function to filter the array

function filterResponseByKey($keyToFilter,$array){
 foreach ($array as $key => $value) 
 {
 if($key == $keyToFilter)
 {
 return $value;
 }
 elseif(is_array($value))
 {
 $result = filterResponseByKey($keyToFilter, $value);
 if($result != false)
 {
 return $result; 
 }
 }
 }
 return false;
}

I'm fairly new to PHP and hope you guys could point me in the right direction and tell me what i am doing wrong here.

I did research on the following (alternate)websites but i couldn't find an answer fitting my needs.

understanding recursion , PHP filter_array

• vaso123: Do not need recurion, just simple loop through. So you want to clear those, where, for example mediacontent width is bigger then a specific value?
• Gerifield: True, don't use recursion and if you just want a few data from the original array, just build a new one and return with that.
• zardilior: I would actually use objects and a class approach but if you really want recursion check my answer
• mickmackusa: This question is unclear because it doesn't include a minimal reproducible example. We don't know if you want the first found match or all found matches. We don't know if recursion is actually necessary. This page is not a good fit for Stack Overflow.

Answer 1

For your specific case I would reccomend you to have an array of objects, as elements 0 and 1 are similar, and have mediacontent as a internal variable.

If your really want to do it you can get an array of mediacontent only by using a map

 array_map($multidimensional_array['entry'],function($obj){
 return $obj['mediagroup']['mediacontent'];
 });

If what you want is something more dynamic and recursive

 function recursive_filter_by_key($keyname,$list){
 $result=[];
 foreach($list as $key=>$obj){
 if($key==$keyname) 
 array_push($result,$obj);
 else if(gettype($obj)=='array')//not necesary to check if its equal to the $key as this wouldn't run if it was
 $result = array_merge($result,recursive_filter_by_key($obj));
 }
 return $result;
 }

This function can return complete arrays within its results array as long as they are the value of the key you are searching

I would like you to comment though as I think I haven't understood your question very much.

Also there is another similar post in the site in case you haven't crossed it How to run array_filter recursively in a PHP array?

Answer 2

The most practical solution for this uses iterators:

$iter = new RecursiveIteratorIterator(
 new RecursiveArrayIterator($multidimensional_array),
 RecursiveIteratorIterator::SELF_FIRST
);
foreach($iter as $key => $value) {
 if(ctype_alpha($key) && $key == 'mediacontent') {
 echo "Media Content: ".print_r($value, true)."\n";
 }
}

This will output:

Media Content: Array
(
 [url] => http://website/urltotheobject.png
 [width] => 384
 [medium] => image
 [type] => image/jpeg
 [height] => 512
)
Media Content: Array
(
 [url] => http://website/urltotheobject.png
 [width] => 512
 [medium] => image
 [type] => image/jpeg
 [height] => 384
)

Iterators are a much underappreciated feature of PHP, although they do have a tricky syntax at times, and in this case you're interested in nodes instead of leaves, requiring the extra mode parameter. The recursive iterators however do simplify a lot of recursive operations.

Answer 3

Your can try this way also for just mediacontent....

$multidimensional_array = array(
 'entry' => array(
 0 => array(
 'width' => array(
 '$t' => '1536'
 ),
 'height' => array(
 '$t' => '2048'
 ),
 'id' => array(
 '$t' => '878974'
 ),
 'mediagroup' => array(
 'mediacontent' => array(
 'url' => 'http://website/urltotheobject.png',
 'width' => 384,
 'medium' => 'image',
 'type' => 'image/jpeg',
 'height' => 512
 )
 )
 ),
 1 => array(
 'width' => array(
 '$t' => '5486'
 ),
 'height' => array(
 '$t' => '1144'
 ),
 'id' => array(
 '$t' => '485435'
 ),
 'mediagroup' => array(
 'mediacontent' => array(
 'url' => 'http://website/urltotheobject.png',
 'width' => 512,
 'medium' => 'image',
 'type' => 'image/jpeg',
 'height' => 384
 )
 )
 )
 )
 );
 function getMediaContent($item){
 return $item['mediagroup']['mediacontent'];
 }
 $mediacontent = array_map('getMediaContent', $multidimensional_array['entry']);
 print '<pre>';
 print_r($mediacontent);

Answer 4

function filterResponseByKey($keyToFilter,$array){
 foreach ($array as $key => $value) 
 {
 if($key === $keyToFilter)
 {
 return $value;
 }
 elseif(is_array($value))
 {
 $result = filterResponseByKey($keyToFilter, $value);
 if($result != false)
 {
 return $result; 
 }
 }
 }
 return false;
}

Now working!

edit: to explain:

Using "==" checks to find if equal regardless of type, so when it encounters a interger, it will cast both values to check as a interger int('anystring') results in 0 , so the key 0 = string 'mediacontent'