PHP multidimensional array key collapse

Question

I'd like to collapse a multidimensional array so that

$arr = array(
    'first' => array(
        'second' => array(
            0 => 'foo',
            1 => 'bar'
        )
    )
);

would collapse to

$arr = array(
    'first[second][0]' => 'foo',
    'first[second][1]' => 'bar'
);

What I'm trying to do is to restore a multipart/form-data $_POST array to the original request body, like this:

------WebKitFormBoundaryxiOccKlMg4Al6VbH
Content-Disposition: form-data; name="first[second][0]"

foo
------WebKitFormBoundaryxiOccKlMg4Al6VbH
Content-Disposition: form-data; name="first[second][1]"

bar
------WebKitFormBoundaryxiOccKlMg4Al6VbH--

Extend the example, by this example your question is vague! Also put your works and what you have done so far. — SAVAFA, May 21 '13 at 15:45
[Possible duplicate](http://stackoverflow.com/questions/526556/how-to-flatten-a-multi-dimensional-array-to-simple-one-in-php) — Jordan Doyle, May 21 '13 at 16:16

Bogdan Burym · Accepted Answer · 2013-05-21T16:11:36.440

0

Try this code:

$arr = array(
    'first' => array(
        'second' => array(
            0 => 'foo',
            1 => 'bar'
        )
    )
);
$result = array();
function processLevel(&$result, $source, $previous_key = null) {
    foreach ($source as $k => $value) {
        $key = $previous_key ? "{$previous_key}[{$k}]" : $k;
        if (!is_array($value)) {
            $result[$key] = $value;
        } else {
            processLevel($result, $value, $key);
        }
    }
}
processLevel($result, $arr);
var_dump($result);
die();

It outputs:

array(2) {
  ["first[second][0]"] => string(3) "foo"
  ["first[second][1]"] => string(3) "bar"

}

edited May 21 '13 at 16:11

answered May 21 '13 at 15:52

Bogdan Burym

5,482
2
27
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please use more self-explaining variable names, so that we can easier know what's happening ;-) – bwoebi May 21 '13 at 16:02
I tried to write it as fast as possible to be the first who posts the answer) – Bogdan Burym May 21 '13 at 16:03
Then change it now, you aren't prohibited from editing... (and yeah, you were the first, my answer was a 6-7 seconds later^^) – bwoebi May 21 '13 at 16:05
obfuscated code would look worse :-P I still understand what's happening, but it isn't suitable for copypasting for example... – bwoebi May 21 '13 at 16:10
Very impressive @BogdanBurim, it's exactly what I was trying to achieve, simple and concise! – Giovanni Lovato May 21 '13 at 16:12

bwoebi · Answer 2 · 2013-05-21T15:57:42.463

function collapseArray ($array, $tree = array(), $step = 0) {
    $result = array();
    foreach ($array as $key => $val) {
        $tree[$step] = $key;
        if (is_scalar($val)) {
            $first = array_shift($tree);
            $result["{$first}[".implode("][", $tree)."]"] = $val;
            array_unshift($tree, $first);
        } else {
            $result += collapseArray($val, $tree, $step + 1);
        }
    }
    return $result;
}

$arr = array(
    'first' => array(
        'second' => array(
            0 => 'foo',
            1 => 'bar'
        )
    )
);

$newArray = collapseArray($arr);

Outputs when var_dump()'ed:

array(2) {
  ["first[second][0]"]=>
  string(3) "foo"
  ["first[second][1]"]=>
  string(3) "bar"
}

score 0 · Answer 3 · answered May 21 '13 at 15:55

0

what about this?

$arr = array(
    'first' => array(
        'second' => array(
            0 => 'foo',
            1 => 'bar'
        )
    )
);
$newArray=array();
foreach($arr['first']['second'] as $k=>$v)
{
    $newArray['first[second]['.$k.']']=$v;
}

var_dump($arr);
var_dump($newArray);

I hope this helps.

answered May 21 '13 at 15:55

Ruslan Polutsygan

4,401
2
26
37

@BogdanBurim: any words about universal solution in question? – Ruslan Polutsygan May 21 '13 at 15:57
It is obvious that it should be universal, also it is obvious that the array he provided is sample. – Bogdan Burym May 21 '13 at 15:58
By the way hello from Kharkiv. – Bogdan Burym May 21 '13 at 15:58
@BogdanBurim: it is not mentioned that array can contain many keys on `first` or `second` level. Seems that only level with integer keys can be adjusted – Ruslan Polutsygan May 21 '13 at 16:00
@BogdanBurim: hello from Kharkiv :) – Ruslan Polutsygan May 21 '13 at 16:01

PHP multidimensional array key collapse

3 Answers3