Question

我试图从我拥有的json文件中仅获取播放列表的名称，但我无法做到

override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void)

这是哪里不工作：

{'playlists': [{'description': '',
                'lastModifiedDate': '2018-11-20',
                'name': 'Piano',
                'numberOfFollowers': 0,
                'tracks': [{'artistName': 'Kenzie Smith Piano',
                            'trackName': "You've Got a Friend in Me (From "
                                         '"Toy Story")'},
                           {'artistName': 'Kenzie Smith Piano',
                            'trackName': 'A Whole New World (From "Aladdin")'},
                           {'artistName': 'Kenzie Smith Piano',
                            'trackName': 'Can You Feel the Love Tonight? (From '
                                         '"The Lion King")'},
                           {'artistName': 'Kenzie Smith Piano',
                            'trackName': "He's a Pirate / The Black Pearl "
                                         '(From "Pirates of the Caribbean")'},
                           {'artistName': 'Kenzie Smith Piano',
                            'trackName': "You'll be in My Heart (From "
                                         '"Tarzan") [Soft Version]'},

import json
from pprint import pprint
json_data=open('C:/Users/alvar/Desktop/Alvaro/Nueva carpeta/Playlist.json', encoding="utf8").read()

playlist = json.loads(json_data)
pprint(playlist)

我想要的是仅提取播放列表的名称。

Answer 1

错误是由于您没有访问字典键'playlists'

for plst in playlist['playlists']:
    print(plst['name'])

# Piano

Answer 2

您遍历了错误的对象。

不要忘记json.loads(json_data)在存储对象时返回该对象。在您的情况下，这是仅包含一个元素的字典：'playlist'。您必须使用loaded_json['playlist']访问此元素，然后遍历播放列表列表。

此处，loaded_json的类型为Dict[List[Dict]]。注意JSON和嵌套数据结构。

尝试：

loaded_json= json.loads(json_data)       #type: Dict[List[dict]]
for playlist in loaded_json['playlist']: #type: dict
    print('{}\n'.format(playlist['name']))

这样做，您将获得所有播放列表的名称。

文档：JSON encoder and decoder

从JSON文件中提取名称

2 个答案: