缓存JSON的类定义

Question

我试图定义一个类，该类返回一个带有歌曲标题、曲目编号和流派类型的字典（这是来自一个特定艺术家对歌曲的iTunesAPI请求）。当前，当我在终端中运行我的文件时，没有返回任何内容（我没有收到语法错误或回溯）。我希望能看到一本有曲目名称、曲目编号和可选体裁的词典。任何帮助都会很好

class Song():
def __init__(self, song_dict={}):
    self.trackName = song_dict["trackName"]
    self.trackNumber = song_dict["trackNumber"]
    self.genre = song_dict["primaryGenreName"]["alternative"]
def __str__(self):

return "{} by {}".format(self.trackName,self.trackNumber,self.genre)

缓存的JSON:

{"http://itunes.apple.com/searchcountry-US_entity-song_format-json_term-bon+iver": {"resultCount": 50, "results": [{"collectionExplicitness": "notExplicit", "releaseDate": "2011-06-21T07:00:00Z", "currency": "USD", "artistId": 273428126, "previewUrl": "http://audio.itunes.apple.com/apple-assets-us-std-000001/AudioPreview71/v4/29/b7/6d/29b76dbc-c7c2-a528-98c0-88250c90d61f/mzaf_8791054078902679680.plus.aac.p.m4a", "trackPrice": 1.29, "isStreamable": true, "trackViewUrl": "https://itunes.apple.com/us/album/holocene/id438685974?i=438685989&uo=4", "collectionName": "Bon Iver", "collectionId": 438685974, "trackId": 438685989, "collectionViewUrl": "https://itunes.apple.com/us/album/holocene/id438685974?i=438685989&uo=4", "trackCount": 10, "trackNumber": 3, "discNumber": 1, "collectionPrice": 9.99, "trackCensoredName": "Holocene", "trackName": "Holocene", "trackTimeMillis": 336613, "primaryGenreName": "Alternative", "artistViewUrl": "https://itunes.apple.com/us/artist/bon-iver/id273428126?uo=4", "kind": "song", "country": "USA", "wrapperType": "track", "artworkUrl100": "http://is3.mzstatic.com/image/thumb/Music/v4/f6/41/9b/f6419bd5-7fa7-6046-04d0-fcae6ecf9d96/source/100x100bb.jpg", "collectionCensoredName": "Bon Iver", "artistName": "Bon Iver", "artworkUrl60": "http://is3.mzstatic.com/image/thumb/Music/v4/f6/41/9b/f6419bd5-7fa7-6046-04d0-fcae6ecf9d96/source/60x60bb.jpg", "trackExplicitness": "notExplicit", "artworkUrl30": "http://is3.mzstatic.com/image/thumb/Music/v4/f6/41/9b/f6419bd5-7fa7-6046-04d0-fcae6ecf9d96/source/30x30bb.jpg", "discCount": 1}, {"contentAdvisoryRating": "Explicit", "collectionExplicitness": "explicit", "releaseDate": "2010-11-22T08:00:00Z", "currency": "USD", "artistId": 2715720, "previewUrl": "http://a1044.phobos.apple.com/us/r30/Music/ac/5a/7b/mzm.wurlfubj.aac.p.m4a", "trackPrice": 1.29, "isStreamable": true, "trackViewUrl": "https://itunes.apple.com/us/album/monster-feat-jay-z-rick-ross-nicki-minaj-bon-iver/id403822142?i=403822318&uo=4", "collectionName": "My Beautiful Dark Twisted Fantasy", "collectionId": 403822142, "trackId": 403822318, "collectionViewUrl": 

Answer 1

两件事：

1. 首先，你有一些你不需要/不想要的等号（意思是，赋值）。这：

   self.trackName =song_dict["trackName"]
   self.trackNumber=song_dict=["trackNumber"]
   self.primaryGenreName =song_dict=["primaryGenreName"]
   

   应该是这样的：

   self.trackName = song_dict["trackName"]
   self.trackNumber = song_dict["trackNumber"]
   self.primaryGenreName = song_dict["primaryGenreName"]
   

2. 接下来，在Python中不会从类构造函数（__init__）返回内容。因此，删除return语句