使用Spotipy / Spotify API的“其他”序列问题

如何解决使用Spotipy / Spotify API的“其他”序列问题

我和我的团队（python的新手）编写了以下代码，以生成与特定城市和相关术语相关的Spotify歌曲。 如果用户输入的城市不在我们的CITY_KEY_WORDS列表中，则它告诉用户输入将被添加到请求文件中，然后将输入写入文件中。 代码如下：

from random import shuffle
from typing import Any,Dict,List
import spotipy
from spotipy.oauth2 import SpotifyClientCredentials
sp = spotipy.Spotify(
    auth_manager=SpotifyClientCredentials(client_id="",client_secret="")
)
CITY_KEY_WORDS = {
    'london': ['big ben','fuse'],'paris': ['eiffel tower','notre dame','louvre'],'manhattan': ['new york','new york city','nyc','empire state','wall street',],'rome': ['colosseum','roma','spanish steps','pantheon','sistine chapel','vatican'],'berlin': ['berghain','berlin wall'],}

def main(city: str,num_songs: int) -> List[Dict[str,Any]]:
    if city in CITY_KEY_WORDS:
        """Searches Spotify for songs that are about `city`. Returns at most `num_songs` tracks."""
        results = []
        # Search for songs that have `city` in the title
        results += sp.search(city,limit=50)['tracks']['items']  # 50 is the maximum Spotify's API allows
        # Search for songs that have key words associated with `city`
        if city.lower() in CITY_KEY_WORDS.keys():
            for related_term in CITY_KEY_WORDS[city.lower()]:
                results += sp.search(related_term,limit=50)['tracks']['items']
        # Shuffle the results so that they are not ordered by key word and return at most `num_songs`
        shuffle(results)
        return results[: num_songs]
    else:
        print("Unfortunately,this city is not yet in our system. We will add it to our requests file.")
        with open('requests.txt','r') as text_file:
            request = text_file.read()
        request = request + city + '\n'
        with open('requests.txt','w+') as text_file:
            text_file.write(request)

def display_tracks(tracks: List[Dict[str,Any]]) -> None:
    """Prints the name,artist and URL of each track in `tracks`"""
    for num,track in enumerate(tracks):
        # Print the relevant details
        print(f"{num + 1}. {track['name']} - {track['artists'][0]['name']} {track['external_urls']['spotify']}")
if __name__ == '__main__':
    city = input("Virtual holiday city? ")
    number_of_songs = input("How many songs would you like? ")
    tracks = main(city,int(number_of_songs))
    display_tracks(tracks)

对于“ if”语句，该代码运行良好（如果有人进入我们列出的城市）。 但是在运行else语句时，在执行完确定的操作后会出现2个错误（它将打印用户的输入并将其写入文件）。

出现的错误是：

Traceback (most recent call last):
  File "...",line 48,in <module>
    display_tracks(tracks)
  File "...",line 41,in display_tracks
    for num,track in enumerate(tracks):
TypeError: 'NoneType' object is not iterable

请原谅我缺乏知识，但是请有人可以帮助解决这个问题吗？

我们也想在最后创建歌曲的播放列表，但是在此方面一直面临困难。

解决方法

在执行if语句时，您将返回一个项目列表，并将其馈送到display_tracks()函数中。但是执行else语句后会发生什么？您可以将请求添加到文本文件中，但不返回任何内容（或NoneType项目）并将其输入display_tracks()中。 display_tracks然后对此NoneType项进行迭代，并引发异常。

您只想在实际有任何曲目要显示的情况下显示曲目。一种实现方法是将对display_tracks()的调用移到您的main函数中，但是如果未在搜索条件中找到任何曲目，则会引发相同的错误。另一个解决方案是首先检查您的tracks是否为空，或者使用类似的

捕获TypeError异常。

tracks = main(city,int(number_of_songs))
try:
    display_tracks(tracks)
except TypeError:
    pass

,

您的main函数在return子句中没有else语句，这导致tracks为None。导致错误的是在tracks上对None进行迭代。 您可以采取一些措施来改善代码：

• 关注点分离：main函数正在做两种不同的事情，检查输入并获取轨道。
• 一开始只做一次.lower()，所以您不必重复。
• 遵循文档约定。
• 在使用前检查响应
• 一些代码清除

请参见下面我上面建议的更改：

def fetch_tracks(city: str,num_songs: int) -> List[Dict[str,Any]]:
    """Searches Spotify for songs that are about `city`.

    :param city: TODO: TBD
    :param num_songs:  TODO: TBD
    :return: at most `num_songs` tracks.
    """
    results = []
    for search_term in [city,*CITY_KEY_WORDS[city]]:
        response = sp.search(search_term,limit=50)
        if response and 'tracks' in response and 'items' in response['tracks']:
            results += response['tracks']['items']
    # Shuffle the results so that they are not ordered by key word and return
    # at most `num_songs`
    shuffle(results)
    return results[: num_songs]


def display_tracks(tracks: List[Dict[str,Any]]) -> None:
    """Prints the name,artist and URL of each track in `tracks`"""
    for num,track in enumerate(tracks):
        # Print the relevant details
        print(
            f"{num + 1}. {track['name']} - {track['artists'][0]['name']} "
            f"{track['external_urls']['spotify']}")


def main():
    city = input("Virtual holiday city? ")
    city = city.lower()
    # Check the input city and handle unsupported cities.
    if city not in CITY_KEY_WORDS:
        print("Unfortunately,this city is not yet in our system. "
              "We will add it to our requests file.")
        with open('requests.txt','a') as f:
            f.write(f"{city}\n")
        exit()

    number_of_songs = input("How many songs would you like? ")
    tracks = fetch_tracks(city,int(number_of_songs))
    display_tracks(tracks)


if __name__ == '__main__':
    main()