如何在Gmail客户端库中的Gmail批量修改API调用中发送消息ID

I have configured everything and working perfectly, As a testing I'm trying to take some filtered emails and update them as read. Single update is working with below code

            $mods = new Google_Service_Gmail_ModifyMessageRequest();
            $mods->setRemoveLabelIds('UNREAD');
            foreach ($messages as $message) {
                try {
                    $message = $service->users_messages->modify($userId, $messageId, $mods);
                    print 'Message with ID: ' . $messageId . ' successfully modified.';
                } catch (Exception $e) {
                    print 'An error occurred: ' . $e->getMessage();
                }
                print 'Message with ID: ' . $message->getId() . '<br/>';
            }

I tried to refer the documentation to find out how to set the parameters to batchmodify function. but there is no details about that. so I read the source files in google client library and found it only accepts three parameters as below.

class Google_Service_Gmail_Resource_UsersMessages extends Google_Service_Resource

public function batchModify($userId, Google_Service_Gmail_BatchModifyMessagesRequest $postBody, $optParams = array())

So I tried below code

        $mods = new Google_Service_Gmail_BatchModifyMessagesRequest();
        $mods->setRemoveLabelIds(['UNREAD']);
        $msgIdString = '';
        foreach ($messages as $message) {
            $id = $message->getId();
            $msgIdString .= " $id";
        }
        echo $msgIdString;
        try {
            $message = $service->users_messages->batchModify($user, $mods);   
        } catch (Exception $e) {
            print 'An error occurred: ' . $e->getMessage();
        }

but this giving me an error

An error occurred: { "error": { "errors": [ { "domain": "global", "reason": "invalidArgument", "message": "No message ids specified." } ], "code": 400, "message": "No message ids specified." } }

So my problem is I still couldn't find the place that I should put the message ids.

After wasting some time on it, I could found it. I'm mentioning here as it will be help to someone in future, Actually the IDs should be an array instead of a string. that's mistake I have done before. So I push all the IDs in to $msgIdArray and sent. now it is working.

        foreach ($messages as $message) {
            $id = $message->getId();
            $msgIdString .= " '$id', ";
            array_push($msgIdArray, $id);
        }
        echo $msgIdString;
        if (!empty($msgIdArray)) {
            $mods = new Google_Service_Gmail_BatchModifyMessagesRequest();
            $mods->setRemoveLabelIds(['UNREAD']);
            $mods->setIds($msgIdArray);
            try {
                $message = $service->users_messages->batchModify($user, $mods);
            } catch (Exception $e) {
                print 'An error occurred: ' . $e->getMessage();
            }
        }