Вы должны описать нам, как выглядит ваша строка JSON.
Может быть, вы можете попробовать этот код ниже:
$user= '[{"name":"Jonathan Suh","email":"jonathan.suh@gmail.com"},
{"name":"William Phil","email":"will.phil@gmail.com"},
{"name":"Allison Kin","email":"allison.kin@gmail.com"}]';
// Replace with your own JSON
$a = json_decode($user, true); // Array
// Create empty array to hold query results
$array = [];
// Begin loop ( foreach )
foreach ($a as $akey => $aloop) {
array_push($array, ['name' => $aloop["name"], 'email' => $aloop["email"]]);
}
// Encode your array result from Loop Process to JSON
// You can change whatever you want to do from your Result Loop
$jsonENC = json_encode($array);
// You know what is this...
echo $jsonENC;