dreamfactory rest api服务器php脚本POST请求pre_process循环运行插入到mysql数据库的很多行

Question

in dreamfactory rest api backend server I have written this php script that is triggered with a POST request in a pre process workflow. This script replaces the received payload with a default payload like this:

{"resource": [{"Time":"2018-12-21T07:49:23","Gas":"111111","Pressure":"1111","Temperature":"11111"}]}

that it will be insert into mysql database table "T":

<?php

$options = [];
$options['headers'] = [];
$options['headers']['Content-Type'] = 'application/json';
$options['parameters'] = [];
$options['parameters']['api_key'] = 'MY_API_KEY';

$api = $platform['api'];
$post = $api->post;

// json string
$json = '{"resource":   [{"Time":"2018-12-21T07:49:23","Gas":"111111","Pressure":"1111","Temperature":"11111"}]}';
// converts json to php array
 $newpayload = json_decode($json, true);

// makes POST call
$result = $post("sensor_sql/_table/t", $newpayload, $options);

var_dump($result);
?>

But when I send a post request to my api rest dreamfactory server with "Fiddler4" program my rest api insert into mysql database many row with the payload like this one: {"Time":"2018-12-21T07:49:23","Gas":"111111","Pressure":"1111","Temperature":"11111"}]} and not only one as it should be. It seems that the script runs many times and not only one when it is called during pre process. Is something missing in my script ? Why the script inserts many row in mysql database and not only one ?