How to traverse into multi-leveled array to get value based on array of key names?

Question

Given the following array of key names in the following format (number of fields can change):

$field_names = Array
(
[0] => web
[1] => results
[2] => result
[3] => title
)

I'd like to access the 'content' key value of the following multi-leveled array:

$values=stdClass Object(
  [web] => Array(
    [results] => Array(
      [result] => Array(
        [title] => Array(
          [type] => default
          [content] => Sample content
        )
      )
    )
  )
)

Sample example how value can be accessed given above arrays:

$value = $values->{$field_names[0]}[$field_names[1]][$field_names[2]][$field_names[3]]['content'];

For the sake of simplicity (keep it plain PHP), I won't get into much details as the existing code is part of some handler which is part of some plugin which is part of some module which is part of another module which is part of content management system in order to parse YQL results, but its logic is broken.

The code looks like:

$field = array_shift($field_names);
$value = $values->$field;
foreach ($field_names as $field) {
  if (is_array($value)) {
    $value = $value[$field];
  }
}

I've tried to do a dirty patch like:

$value = is_string($value[$field]) ? $value[$field] : $value[$field]['content'];

And it worked for one example, but it doesn't work for all cases, like one above.

I'm aware of recursive functions and array_walk_recursive(), but I'd like to avoid headache of using them in order to make it simple as possible.

Is there any simple way of accessing value of multi-leveled array having dynamic array of key names?

Somewhat related: stackoverflow.com/questions/1677099/…

Marc B
– Marc B

2015-02-19 21:01:20 +00:00
Commented Feb 19, 2015 at 21:01 — Marc B
– Marc B, Commented Feb 19, 2015 at 21:01

Adam · Accepted Answer · 2015-02-19 21:51:05Z

2

Recursive solutions can also be simple

Your data:

$field_names = Array("web", "results","result","title");
$values->web["results"]["result"]["title"]=
            Array("type"=> "default", "content"=>"Sample content");

The function:

function getField($obj, $keys) {
    return ($key=array_shift($keys)) ? getField($obj[$key], $keys) : $obj["content"];
}

echo getField((Array)$values, $field_names);

But if you want a not recursive one, here it is:

$obj=(Array)$values;
while ($key=array_shift($field_names)) $obj=$obj[$key];
echo $obj['content'];

answered Feb 19, 2015 at 21:51

Adam

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3 Comments

kenorb Over a year ago

Tested recursive one-liner, really simple and works great, thanks. Posted patch here.

greg_diesel Over a year ago

Look at that @Adam . You just helped a commit to Drupal!

Adam Over a year ago

If they don't give my name to the next version, I don't understand. ;-)

Community · Accepted Answer · 2017-05-23 10:24:09Z

1

Here's a simple way, not recursive using a reference (taken from How to write getter/setter to access multi-level array by key names?):

function get($object, $path) {
    $prop = array_shift($path);
    $temp =& $object->$prop;

    foreach($path as $key) {
        $temp =& $temp[$key];
    }
    return $temp;
}

$value = get($values, $field_names)['content']; //PHP 5.4.0

edited May 23, 2017 at 10:24

CommunityBot

11 silver badge

answered Feb 19, 2015 at 21:25

AbraCadaver

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