解析 JSON 对象的问题

Question

我的网站调用 Spotify Web API 并获取给定用户的所有公共播放列表。响应最初是 JSON，但我的代码对其进行了解码。

我想要代码做的下一件事是只显示对象 [external_urls]、[name] 和 [tracks] 对于响应中的每个项目。为此，我已经尝试过：

foreach($response_2['items'] as $item) {
echo 'Link: ' . $item['external_urls'] . '<br />'; 
echo 'Name: ' . $item['name'] . '<br />';
echo 'Tracks: ' . $item['tracks'] . '<br />'; }

...但它不能正常工作。所有 [name] 对象（即a string）都正确回显，但对于所有 [external_urls] 和 [tracks]（其中是objects) 它只在浏览器中显示“数组”。

我想我应该对这些对象使用 print_r()，但我无法让它工作。

有什么建议吗？

我的代码：

<?php

$url = 'https://accounts.spotify.com/api/token';
$method = 'POST';

$credentials = "hidden:hidden";

$headers = array(
        "Accept: */*",
        "Content-Type: application/x-www-form-urlencoded",
        "Authorization: Basic " . base64_encode($credentials));
$data = 'grant_type=client_credentials';

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $url);
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $data);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response_1 = curl_exec($ch);

curl_close($ch);

$response_1 = json_decode($response_1, true);

$token = $response_1['access_token'];

$headers_2 = array(
        "Accept: */*",
        "Content-Type: application/x-www-form-urlencoded",
        ('Authorization: Bearer ' . $token));

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL,'https://api.spotify.com/v1/users/wizzler/playlists');
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers_2);
curl_setopt($ch, CURLOPT_POST, false);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$response_2 = curl_exec($ch);

curl_close($ch);

$response_2 = json_decode($response_2, true);

?>

API 响应：

{
    "href": "https://api.spotify.com/v1/users/wizzler/playlists",
    "items": [
        {
            "collaborative": false,
            "external_urls": {
                "spotify": "http://open.spotify.com/user/wizzler/playlists/53Y8wT46QIMz5H4WQ8O22c"
            },
            "href": "https://api.spotify.com/v1/users/wizzler/playlists/53Y8wT46QIMz5H4WQ8O22c",
            "id": "53Y8wT46QIMz5H4WQ8O22c",
            "name": "Wizzlers Big Playlist",
            "owner": {
                "external_urls": {
                    "spotify": "http://open.spotify.com/user/wizzler"
                },
                "href": "https://api.spotify.com/v1/users/wizzler",
                "id": "wizzler",
                "type": "user",
                "uri": "spotify:user:wizzler"
            },
            "public": true,
            "tracks": {
                "href": "https://api.spotify.com/v1/users/wizzler/playlists/53Y8wT46QIMz5H4WQ8O22c/tracks",
                "total": 30
            },
            "type": "playlist",
            "uri": "spotify:user:wizzler:playlist:53Y8wT46QIMz5H4WQ8O22c"
        },
        {
            "collaborative": false,
            "external_urls": {
                "spotify": "http://open.spotify.com/user/wizzlersmate/playlists/1AVZz0mBuGbCEoNRQdYQju"
            },
            "href": "https://api.spotify.com/v1/users/wizzlersmate/playlists/1AVZz0mBuGbCEoNRQdYQju",
            "id": "1AVZz0mBuGbCEoNRQdYQju",
            "name": "Another Playlist",
            "owner": {
                "external_urls": {
                    "spotify": "http://open.spotify.com/user/wizzlersmate"
                },
                "href": "https://api.spotify.com/v1/users/wizzlersmate",
                "id": "wizzlersmate",
                "type": "user",
                "uri": "spotify:user:wizzlersmate"
            },
            "public": true,
            "tracks": {
                "href": "https://api.spotify.com/v1/users/wizzlersmate/playlists/1AVZz0mBuGbCEoNRQdYQju/tracks",
                "total": 58
            },
            "type": "playlist",
            "uri": "spotify:user:wizzlersmate:playlist:1AVZz0mBuGbCEoNRQdYQju"...
        }
    ],
    "limit": 9,
    "next": null,
    "offset": 0,
    "previous": null,
    "total": 9
}

Answer 1

external_urls 和 tracks 都是对象。为了获取数据，您要么需要知道确切的属性，要么将它们转换为数组(array) 并遍历新创建的数组以确保输出所有值。由于名称是复数形式，我假设您可以拥有多个外部网址和多个曲目。出于这个原因，我将属性转换为数组并遍历它们：

foreach($response_2['items'] as $item) {
    echo "LINKS <br />";
    $item['external_urls'] = (array)$item['external_urls'];
    foreach($item['external_urls'] as $key => $value) {
        echo ucfirst($key) . ": " . $value . "<br />";
    }
    echo "Name: " . $item['name'] . "<br />";
    echo "TRACKS <br />";
    $item['tracks'] = (array)$item['tracks'];
    foreach($item['tracks'] as $key => $value) {
        echo ucfirst($key) . ": " . $value . "<br />";
    } 
}

或者，如果您知道您将只有一个 url 和一个轨道并且您知道属性名称，则可以使用对象语法object->key; 访问属性。上面的相同示例在下面使用对象语法重写：

foreach($response_2['items'] as $item) {
    echo "LINKS <br />";
    echo "Spotify: " . $item['external_urls']->spotify . "<br />";
    echo "Name: " . $item['name'] . "<br />";
    echo "TRACKS <br />";
    echo "Href: " . $item['tracks']->href . "<br />";
    echo "Total: " . $item['tracks']->total . "<br />";
}

第 1 项的示例输出：

LINKS
Spotify: http://open.spotify.com/user/wizzler/playlists/53Y8wT46QIMz5H4WQ8O22c
Name: Wizzlers Big Playlist
TRACKS
Href: https://api.spotify.com/v1/users/wizzler/playlists/53Y8wT46QIMz5H4WQ8O22c/tracks
Total: 30