Python 除了特定的键错误

Question

我正在使用 Beautiful Soup 解析 XML 文件。有时我的条目缺少一个或多个我正在解析的键。我想设置异常来处理这个。我的代码看起来像这样：

for entry in soup.findAll('entry_name'):
    try:
        entry_dict = dict(entry.attrs)
        x = entry_dict["x"]
        y = entry_dict["y"]
        z = entry_dict["z"]

        d[x] = [y, z]
    except KeyError: 
        y = "0"
        d[x] = [y, z]

问题是我可能会缺少 "y"、"z" 或两者 "y and z"，具体取决于条目。有没有办法处理特定的 KeyErrors？像这样：

except KeyError "y":
except KeyError "z":
except KeyError "y","z":

Answer 1

您可以检查异常参数：

a = {}
try:
    a['a']
except KeyError as e:
    # handle key errors you want
    if e.args[0] == 'a':
        pass
    # reraise the exception if not handled
    else:
        raise

Answer 2

就个人而言，我不会在这里使用 try/except，而是采用检测方法而不是处理方法。

if not 'y'  in entry_dict.keys() and not 'z' in entry_dict.keys():
  # handle y and z missing
elif not 'y' in entry_dict.keys():
  # handle missing y
elif not 'z' in entry_dict.keys():
  # handle missing z

Answer 3

答案略有不同：

a = {}
try:
    a['a']
except KeyError as e:
    # 2 other ways to check what the missing key was
    if 'a' in e.args:
        pass
    if 'a' in e:
        pass
    # reraise the exception if not handled
    else:
        raise

Python 除了特定的键错误

Python Except Specific Key Error

python

xml

exception-handling

beautifulsoup

keyerror