如何在PHP中的闭包之外填充数组？

Question

I wrote this

 $result = array();

        array_map(function($row) use ($result) {
            $result[$row->id] = array();
            $result[$row->id]['geojson'] = $row->geojson;
        }, $regions);

and $result is empty at the end.

Is it possible to populate array this way?

Answer 1

$result inside the function is a copy of the outer array, so changes you make don't affect the original. You need to use a reference: use (&$result)

array_map(function($row) use (&$result) {
    $result[$row->id] = array();
    $result[$row->id]['geojson'] = $row->geojson;
}, $regions);

Or you could simply use foreach

foreach ($regions as $row) {
    $result[$row->id] = array();
    $result[$row->id]['geojson'] = $row->geojson;
}