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获取导致异常的异常描述和堆栈跟踪，全部作为字符串

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我在Python中看到了很多关于堆栈跟踪和异常的帖子 . 但还没找到我需要的东西 .

我有一大堆Python 2.7代码可能引发异常 . 我想 grab 它并分配给 string 它的完整描述和导致错误的堆栈跟踪（我们只是在控制台上看到的所有内容） . 我需要这个字符串将其打印到GUI中的文本框 .

像这样的东西：

try:
    method_that_can_raise_an_exception(params)
except Exception as e:
    print_to_textbox(complete_exception_description(e))

问题是： what is the function complete_exception_description?

python exception-handling stack-trace

8 回答

  • 6

    使用Python 3，以下代码将使用 traceback.format_exc() 完全按照格式获取 Exception 对象：

    import traceback

try: 
    method_that_can_raise_an_exception(params)
except Exception as ex:
    print(''.join(traceback.format_exception(etype=type(ex), value=ex, tb=ex.__traceback__)))

    优点是只需要 Exception 对象（由于记录的 __traceback__ 属性），因此可以更容易地作为参数传递给另一个函数以进行进一步处理 .

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  • 23

    请参阅 traceback 模块，特别是 format_exc() 函数 . Here .

    import traceback

try:
    raise ValueError
except ValueError:
    tb = traceback.format_exc()
else:
    tb = "No error"
finally:
    print tb
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  • 0
    >>> import sys
>>> import traceback
>>> try:
...   5 / 0
... except ZeroDivisionError, e:
...   type_, value_, traceback_ = sys.exc_info()
>>> traceback.format_tb(traceback_)
['  File "<stdin>", line 2, in <module>\n']
>>> value_
ZeroDivisionError('integer division or modulo by zero',)
>>> type_
<type 'exceptions.ZeroDivisionError'>
>>>
>>> 5 / 0
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ZeroDivisionError: integer division or modulo by zero

    使用 sys.exc_info() 收集 traceback 模块中的信息和函数以对其进行格式化 . Here是格式化它的一些示例 .

    整个异常字符串位于：

    >>> ex = traceback.format_exception(type_, value_, traceback_)
>>> ex
['Traceback (most recent call last):\n', '  File "<stdin>", line 2, in <module>\n', 'ZeroDivisionError: integer division or modulo by zero\n']
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  • 32

    获取导致异常的异常描述和堆栈跟踪，全部作为字符串

    要创建一个相当复杂的堆栈跟踪来演示我们获得完整的堆栈跟踪：

    def raise_error():
    raise RuntimeError('something bad happened!')

def do_something_that_might_error():
    raise_error()

    记录完整的堆栈跟踪

    最佳做法是为模块设置 Logger . 它将知道模块的名称并能够更改级别（以及其他属性，例如处理程序）

    import logging
logging.basicConfig(level=logging.DEBUG)
logger = logging.getLogger(__name__)

    我们可以使用此 Logger 来获取错误：

    try:
    do_something_that_might_error()
except Exception as error:
    logger.exception(error)

    哪些日志：

    ERROR:__main__:something bad happened!
Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "<stdin>", line 2, in do_something_that_might_error
  File "<stdin>", line 2, in raise_error
RuntimeError: something bad happened!

    所以我们得到的输出与出错时的输出相同：

    >>> do_something_that_might_error()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 2, in do_something_that_might_error
  File "<stdin>", line 2, in raise_error
RuntimeError: something bad happened!

    获取字符串

    如果你真的只想要字符串，请使用 traceback.format_exc 函数，演示如何在此处记录字符串：

    import traceback
try:
    do_something_that_might_error()
except Exception as error:
    just_the_string = traceback.format_exc()
    logger.debug(just_the_string)

    哪些日志：

    DEBUG:__main__:Traceback (most recent call last):
  File "<stdin>", line 2, in <module>
  File "<stdin>", line 2, in do_something_that_might_error
  File "<stdin>", line 2, in raise_error
RuntimeError: something bad happened!
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  • 5

    对于那些使用 Python-3 的人

    使用 traceback 模块和 exception.__traceback__ 可以提取堆栈跟踪，如下所示：

    • 使用 traceback.extract_stack() 抓取 current 堆栈跟踪

    • 删除最后三个元素（因为那些是堆栈中的条目让我进入我的调试功能）

    • 使用 traceback.extract_tb() 从异常对象追加 __traceback__

    • 使用 traceback.format_list() 格式化全部内容

    import traceback
def exception_to_string(excp):
   stack = traceback.extract_stack()[:-3] + traceback.extract_tb(excp.__traceback__)  # add limit=?? 
   pretty = traceback.format_list(stack)
   return ''.join(pretty) + '\n  {} {}'.format(excp.__class__,excp)

    一个简单的演示：

    def foo():
    try:
        something_invalid()
    except Exception as e:
        print(exception_to_string(e))

def bar():
    return foo()

    当我们调用 bar() 时，我们得到以下输出：

    File "./test.py", line 57, in <module>
    bar()
  File "./test.py", line 55, in bar
    return foo()
  File "./test.py", line 50, in foo
    something_invalid()

  <class 'NameError'> name 'something_invalid' is not defined
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  • 30

    您也可以考虑使用内置的Python模块cgitb来获得一些非常好的，格式良好的异常信息，包括局部变量值，源代码上下文，函数参数等 .

    比如这个代码......

    import cgitb
cgitb.enable(format='text')

def func2(a, divisor):
    return a / divisor

def func1(a, b):
    c = b - 5
    return func2(a, c)

func1(1, 5)

    我们得到这个异常输出......

    ZeroDivisionError
Python 3.4.2: C:\tools\python\python.exe
Tue Sep 22 15:29:33 2015

A problem occurred in a Python script.  Here is the sequence of
function calls leading up to the error, in the order they occurred.

 c:\TEMP\cgittest2.py in <module>()
    7 def func1(a, b):
    8   c = b - 5
    9   return func2(a, c)
   10
   11 func1(1, 5)
func1 = <function func1>

 c:\TEMP\cgittest2.py in func1(a=1, b=5)
    7 def func1(a, b):
    8   c = b - 5
    9   return func2(a, c)
   10
   11 func1(1, 5)
global func2 = <function func2>
a = 1
c = 0

 c:\TEMP\cgittest2.py in func2(a=1, divisor=0)
    3
    4 def func2(a, divisor):
    5   return a / divisor
    6
    7 def func1(a, b):
a = 1
divisor = 0
ZeroDivisionError: division by zero
    __cause__ = None
    __class__ = <class 'ZeroDivisionError'>
    __context__ = None
    __delattr__ = <method-wrapper '__delattr__' of ZeroDivisionError object>
    __dict__ = {}
    __dir__ = <built-in method __dir__ of ZeroDivisionError object>
    __doc__ = 'Second argument to a division or modulo operation was zero.'
    __eq__ = <method-wrapper '__eq__' of ZeroDivisionError object>
    __format__ = <built-in method __format__ of ZeroDivisionError object>
    __ge__ = <method-wrapper '__ge__' of ZeroDivisionError object>
    __getattribute__ = <method-wrapper '__getattribute__' of ZeroDivisionError object>
    __gt__ = <method-wrapper '__gt__' of ZeroDivisionError object>
    __hash__ = <method-wrapper '__hash__' of ZeroDivisionError object>
    __init__ = <method-wrapper '__init__' of ZeroDivisionError object>
    __le__ = <method-wrapper '__le__' of ZeroDivisionError object>
    __lt__ = <method-wrapper '__lt__' of ZeroDivisionError object>
    __ne__ = <method-wrapper '__ne__' of ZeroDivisionError object>
    __new__ = <built-in method __new__ of type object>
    __reduce__ = <built-in method __reduce__ of ZeroDivisionError object>
    __reduce_ex__ = <built-in method __reduce_ex__ of ZeroDivisionError object>
    __repr__ = <method-wrapper '__repr__' of ZeroDivisionError object>
    __setattr__ = <method-wrapper '__setattr__' of ZeroDivisionError object>
    __setstate__ = <built-in method __setstate__ of ZeroDivisionError object>
    __sizeof__ = <built-in method __sizeof__ of ZeroDivisionError object>
    __str__ = <method-wrapper '__str__' of ZeroDivisionError object>
    __subclasshook__ = <built-in method __subclasshook__ of type object>
    __suppress_context__ = False
    __traceback__ = <traceback object>
    args = ('division by zero',)
    with_traceback = <built-in method with_traceback of ZeroDivisionError object>

The above is a description of an error in a Python program.  Here is
the original traceback:

Traceback (most recent call last):
  File "cgittest2.py", line 11, in <module>
    func1(1, 5)
  File "cgittest2.py", line 9, in func1
    return func2(a, c)
  File "cgittest2.py", line 5, in func2
    return a / divisor
ZeroDivisionError: division by zero
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  • 0

    我的2美分：

    import sys, traceback
try: 
  ...
except Exception, e:
  T, V, TB = sys.exc_info()
  print ''.join(traceback.format_exception(T,V,TB))
    回复于
  • 455

    我定义了以下助手类：

    import traceback
class TracedExeptions(object):
    def __init__(self):
        pass
    def __enter__(self):
        pass

    def __exit__(self, etype, value, tb):
      if value :
        if not hasattr(value, 'traceString'):
          value.traceString = "\n".join(traceback.format_exception(etype, value, tb))
        return False
      return True

    以后我可以这样使用：

    with TracedExeptions():
  #some-code-which-might-throw-any-exception

    以后可以像这样使用它：

    def log_err(ex):
  if hasattr(ex, 'traceString'):
    print("ERROR:{}".format(ex.traceString));
  else:
    print("ERROR:{}".format(ex));

    （背景：由于将 Promise 与 Exception 一起使用，我很沮丧，不幸的是，它将一个地方引发的异常传递给另一个地方的on_rejected处理程序，因此很难从原始位置获取回溯）

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