How to store Array of objects into redis cache using php

I Have an array of objects that I need to store into redis cache and use it later.

$obj = array(
                'request_id' => $request_id,
                'request_start_dttm' => $start_time,
                'client_id' => $clientId,
            );

            $redis = Redis::connection();
            $name = "API".bin2hex(random_bytes(3));
            $redis->rpush($name,$obj);
            print_r($redis->lrange($name,0,-1));

But I get the output as following:

array (
    0 => '1732478',
    1 => '2021-10-18 12:55:39.000000',
    2 => '3'
)

What should I do to preserve the key value pair using redis php?