implode on field

function implode_on_field($delimiter, Array $objects, $field)
{
$d = array();

foreach ($objects as $ob)
$d[] = $ob->{$field};

return implode($delimiter, $d);
}

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example:

$obj = array();
for ($i = 0; $i < 5; $i++) {
$obj[] = array('id' => $i, 'type' => 'x');
}

$out = implode_on_field(',', $obj, 'id');

echo $out;

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output:

1,2,3,4,5