usort($childs, function($a, $b) {
return $a['parent_id'] - $b['parent_id'];
});
Here I'm sorting it by 1 field, how can I add more fields to sort them?, Like if it was the ORDER BY field1, field2, field3 in Mysql
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1this may shed some light stackoverflow.com/questions/4582649/…user1978142– user19781422014-05-27 10:49:08 +00:00Commented May 27, 2014 at 10:49
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1 Answer
usort($childs, function($a, $b) {
if ($a['field1'] == $b['field1']) {
if ($a['field2'] == $b['field2']) {
return $a['field3'] < $b['field3'] ? -1 : 1;
} else {
return 0;
}
return $a['field2'] < $b['field2'] ? -1 : 1;
}
return $a['field1'] < $b['field1'] ? -1 : 1;
});
EDIT
a slightly more generic solution (untested)
$sorts = array('field1' => 'asc', 'field2' => 'asc', 'field3' => 'asc');
usort($childs, function($a, $b) use (array $sorts = array()) {
foreach($sorts as $field => $direction) {
if ($a[$field] != $b[$field]) {
if ($direction == 'asc') {
return $a[$field] < $b[$field] ? -1 : 1;
}
return $a[$field] < $b[$field] ? 1 : -1;
}
}
return 0;
});
5 Comments
deceze
Wouldn't
if ($a[1] != $b[1]) return ...; if ($a[2] != $b[2]) return ... be much more readable...? :)
kero
Why additional logic and not just
return $a[..] - $b[..];?
Mark Baker
@deceze - probably, just trying to provide a literal answer to OP's question using usort() rather than array_multisort().... and with an eye to making it more generic by passing an array (['field1' => 'asc', 'field2' => 'asc', 'field3' => 'asc']) in as well via
use... though I'm not sure I have the time to make that effort at the momentdeceze
Especially in a
usort callback, I wouldn't use this right-indenting nested if style. Also, if you're comparing numbers, $a - $b is fine for returning < 0, 0 and > 0. For strings I'd use strcmp, which accomplishes the same. Also see stackoverflow.com/a/22829326/476Mark Baker
Yes, strcmp is definitely better all round for comparing strings, when you know they're strings