Question

我正在尝试使用Python从包含有关歌曲元数据的JSON对象中提取多个元素。为了测试信息是否可用，我正在为每个元数据元素使用try语句。另外，对于我稍后需要在程序中执行的一些字符串处理，我将每个值保存在不同的变量中。

有关如何改进以下代码的任何建议，以便不为每个不同的元数据值创建try / except语句？

if len(r['response']['songs']) is not 0:
    # Request information about the artist
    artist_desc_string = "http://developer.echonest.com/api/v4/artist/terms?api_key="+api_key+\
                         "&name="+artist+"&format=json"
    r2 = requests.get(artist_desc_string).json()

    # Extract information from the song JSON
    try:
        title = r['response']['songs'][0]['title']
    except (IndexError, KeyError):
        title = "NULL"

    try:
        artist_name = r['response']['songs'][0]['artist_name']
    except (IndexError, KeyError):
        artist_name = "NULL"

    try:
        artist_location = r['response']['songs'][0]['artist_location']['location'].replace(',','*')
    except (IndexError, KeyError):
        artist_location = "NULL"

    try:
    ...
    ...

Answer 1

这样的事可能吗？

def get_or_dont(d,list_of_keys):
    d2 = d
    while list_of_keys:
        try:
            d2 = d2[list_of_keys.pop(0)]
            if not list_of_keys: return d2
        except:
            break
    return "Null"

r = {'response':{
'a':5,
'b':{'6':{'5':3}},
'c':[1,2,3]
}}
print get_or_dont(r['response'],["b","6"])

Answer 2

也许这可能会有所帮助：

def get_value(d, keys):
    try:
        if keys:
            for i in range(len(keys)):
                key = keys[i]
                return get_value(d[key], keys[i+1:])
        return d
    except (IndexError, KeyError):
        return "Null"


>>> d = {'person': {'name': {'first': 'aamir'}}}
>>> get_value(d, ['person', 'name', 'first'])
aamir

Answer 3

使用包含所有可能属性的for循环...

attribs = {'title': None, 'artist_name':None, 'location': None, 'etc': None} for key in attribs: try: attribs[key] = r['response']['songs'][0][key] except (IndexError, KeyError): attribs[key] = "NULL"

这样你只需要管理dict attribs ...

就获取意外属性而言，您总是可以获取JSON对象的键并在attribs中创建更多条目

如何在Python中改进try语句的重复使用？

3 个答案: