PHP multidimensional array key collapse - php

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--

Answer 1

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"
}

Answer 2

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.

Answer 3

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"
}