我在我的代码中有这个try块:
try:
do_something_that_might_raise_an_exception()
except ValueError as err:
errmsg = 'My custom error message.'
raise ValueError(errmsg)
严格地说，我实际上引发了另一个ValueError，而不是do_something…()抛出的ValueError，在这种情况下被称为err。如何将自定义消息附加到错误?我尝试以下代码，但失败，由于错误，ValueError实例，不可调用:
try:
do_something_that_might_raise_an_exception()
except ValueError as err:
errmsg = 'My custom error message.'
raise err(errmsg)
当前回答
上面的解决方案都没有完全满足我的要求，即在错误消息的第一部分添加一些信息，即我希望我的用户首先看到我的自定义消息。
这招对我很管用:
exception_raised = False
try:
do_something_that_might_raise_an_exception()
except ValueError as e:
message = str(e)
exception_raised = True
if exception_raised:
message_to_prepend = "Custom text"
raise ValueError(message_to_prepend + message)
其他回答
这个代码模板应该允许您用自定义消息引发异常。
try:
raise ValueError
except ValueError as err:
raise type(err)("my message")
It seems all the answers are adding info to e.args[0], thereby altering the existing error message. Is there a downside to extending the args tuple instead? I think the possible upside is, you can leave the original error message alone for cases where parsing that string is needed; and you could add multiple elements to the tuple if your custom error handling produced several messages or error codes, for cases where the traceback would be parsed programmatically (like via a system monitoring tool).
## Approach #1, if the exception may not be derived from Exception and well-behaved:
def to_int(x):
try:
return int(x)
except Exception as e:
e.args = (e.args if e.args else tuple()) + ('Custom message',)
raise
>>> to_int('12')
12
>>> to_int('12 monkeys')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 3, in to_int
ValueError: ("invalid literal for int() with base 10: '12 monkeys'", 'Custom message')
or
## Approach #2, if the exception is always derived from Exception and well-behaved:
def to_int(x):
try:
return int(x)
except Exception as e:
e.args += ('Custom message',)
raise
>>> to_int('12')
12
>>> to_int('12 monkeys')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 3, in to_int
ValueError: ("invalid literal for int() with base 10: '12 monkeys'", 'Custom message')
你能看出这种方法的缺点吗?
引发相同的错误，并在前面添加自定义文本消息。 (编辑-抱歉，实际上和https://stackoverflow.com/a/65494175/15229310一样，为什么有10个(好评)“解决方案”只是不回答张贴的问题?)
try:
<code causing exception>
except Exception as e:
e.args = (f"My custom text. Original Exception text: {'-'.join(e.args)}",)
raise
使用的错误消息引发新的异常
raise Exception('your error message')
or
raise ValueError('your error message')
在你想要引发它或使用'from'将错误消息附加(替换)到当前异常的地方(Python 3。只支持X):
except ValueError as e:
raise ValueError('your message') from e
如果你想自定义错误类型，你可以做的一件简单的事情就是基于ValueError定义一个错误类。
