php - json_encode，[括号]中需要的关联数组

Question

我正在使用 PHP，为了使用 Curl 将一些数据提供给 API，我需要格式化一些字符串并且一直在使用 json_encode。它适用于更简单的位，但我无法弄清楚:

API 期望这样:

{
  "id": "string",
  "startTime": "2017-04-18T08:04:23.167Z",
  "endTime": "2017-04-18T08:04:23.167Z",
  "contacts": [
    {
      "id": "string",
      "displayName": "string"
    }

到目前为止我的代码:

$data_set_pre = array(
    "id" => "",
    "startTime" => "2017-04-14T07:47:59.028Z",
    "endTime" => "2017-04-15T07:47:59.028Z",
    "contacts" => array("id" => "ahashofsomenumbersandletters", "displayName" =>  "John Doe"),
  );
$data_set = json_encode($data_set_pre);

不幸的是，这会产生:

{"id":"","startTime":"2017-04-14T07:47:59.028Z","endTime":"2017-04-15T07:47:59.028Z","contacts":{"id":"ahashofsomenumbersandletters","displayName":"John Doe"}}

我一直在研究，我得到的印象是 json_encode 将对所有内容进行编码，但一个从 0 开始的完整顺序数组作为对象，我现在不知道如何解决这个问题。(不，我无法更改 API 的要求，它由第三方提供)。

Answer 1

<?php
$data_set_pre = array(
    "id" => "12",
    "startTime" => "2017-04-14T07:47:59.028Z",
    "endTime" => "2017-04-15T07:47:59.028Z",
    "contacts" => array(
                    array(
                        "id" => "ahashofsomenumbersandletters", "displayName" =>  "John Doe"
                        )
                )
    );
$data_set = json_encode($data_set_pre);