如何从POST请求“看到”json响应（webhook）

我在Dialogflow中创建了一个聊天机器人，它告诉用户我（扩展）家庭的成员以及他们住在哪里 . 我已经创建了一个包含MySQL的小型数据库，其中存储了这些数据，并且只要这是合适的，我就会使用PHP脚本（在Heroku上托管）来获取它们，具体取决于用户与聊天机器人的交互 . 我的PHP脚本从Dialogflow接收POST请求（webhook）如下：

<?php

$dbServername = '******************';
$dbUsername = '******************';
$dbPassword = '******************';
$dbName = '******************';
$conn = mysqli_connect($dbServername, $dbUsername, $dbPassword, $dbName);

header('Content-Type: application/json');
$method = $_SERVER['REQUEST_METHOD'];

if($method == 'POST'){
    $requestBody = file_get_contents('php://input');
    $json = json_decode($requestBody);

    $action = $json->result->action;
    $first_name = $json->result->contexts[0]->parameters->{'given-name'};
    $last_name = $json->result->contexts[0]->parameters->{'last-name'};
    $lifespan = $json->result->contexts[0]->lifespan;

    $sql = "SELECT * FROM family WHERE name LIKE '%$first_name%$last_name%';";
    $result = mysqli_query($conn, $sql);
    $resultCheck = mysqli_num_rows($result);
    if ($resultCheck > 0) {
       while ($row = mysqli_fetch_assoc($result)) {
            $person = $row;
       }

       switch ($action) {
           case 'Name':
               $speech= "$first_name is my" . $person["name"] . ".";
               break;  
           case 'Location':
               $speech = "$first_name is living in {$person["location"]}.";
               break;
           default:
               $speech = "Please ask me something more relevant to my family";
               break;
       } 
    }
    else {

        $speech = "Sorry, $first_name $last_name is not a member of my family.";

    }

    $response = new \stdClass();
    $response->speech = $speech;
    $response->displayText = $speech;
    $response->source = "agent";
    echo json_encode($response);
}
else
{
    echo "Method not allowed";
}
?>

I can instantly see on Dialogflow the json response that I am receiving from it in my PHP script. However, Google Assistant does not provide this option. The problem also is that the json response when using Google Assistant is considerably different than the one when using only Dialogflow.

My question is: how can I "see" what JSON is being sent to my PHP script when using the Google Assistant? In other words, how can I "see" the whole of $requestBody variable at once?

例如，我尝试使用https://webhook.site/并填写以下信息以创建新的URL / endpoints ：

Default status code ->  200
Content Type -> application/json
Timeout before response -> 0
Response body -> {
 "speech": "WEBHOOK",
 "displayText": "WEBHOOK",
 "source": "agent"
}

响应主体具有与PHP脚本相同的结构 . 但是，出于某种原因，Google智能助理不会从此自定义 endpoints 收到json响应（而Dialogflow确实会收到它完美） . 因此，我不能完全继续前进，看看Dialogflow和Google智能助理发送的是什么，意图由上下文进一步触发...