获取引起异常的异常描述和堆栈跟踪，全部作为字符串

我看过很多关于Python中堆栈跟踪和异常的文章。但是还没有找到我所需要的。

我有一段Python 2.7代码可能会引发异常。我想捕获它并将其完整描述和导致错误的堆栈跟踪分配给字符串（只是我们在控制台上看到的所有内容）。我需要此字符串以将其打印到GUI中的文本框中。

像这样：

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

问题是：函数是什么complete_exception_description？

请参阅traceback模块，特别是format_exc()功能。在这里。

import traceback

try:
    raise ValueError
except ValueError:
    tb = traceback.format_exc()
else:
    tb = "No error"
finally:
    print tb

让我们创建一个相当复杂的堆栈跟踪，以证明我们获得了完整的堆栈跟踪：

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一个记录器。它将知道模块的名称，并能够更改级别（在其他属性（例如处理程序）中）

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

我们可以使用此记录器来获取错误：

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

哪个日志：

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!

因此，我们得到与发生错误时相同的输出：

>>> 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!

仅获取字符串

如果您真的只想要字符串，请改用traceback.format_exc函数，在此处演示如何记录字符串：

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

哪个日志：

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!

对于Python 3，以下代码将Exception完全按照使用traceback.format_exc()以下命令获得的格式格式化对象：

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__)))

优点是仅Exception需要对象（由于记录的__traceback__属性），因此可以更轻松地将其作为参数传递给另一个函数以进行进一步处理。

>>> import sys
>>> import traceback
>>> try:
...   5 / 0
... except ZeroDivisionError as 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

您使用sys.exc_info（）来收集信息和traceback模块中的函数以对其进行格式化。 以下是一些格式化示例。

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']

对于那些使用Python-3的人

使用tracebackmodule和exception.__traceback__one可以提取堆栈跟踪，如下所示：

• 使用获取当前的堆栈跟踪traceback.extract_stack()
• 删除最后三个元素（因为那些是使我进入调试功能的堆栈中的条目）
• __traceback__使用以下方法从异常对象追加traceback.extract_tb()
• 使用格式化整个东西 traceback.format_list()

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()

调用时，将得到以下输出bar()：

  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

您可能还会考虑使用内置的Python模块cgitb来获取一些非常好且格式正确的异常信息，包括局部变量值，源代码上下文，函数参数等。

例如此代码...

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

如果您希望在不处理异常的情况下获得相同的信息，则可以执行以下操作。这样做import traceback，然后：

try:
    ...
except Exception as e:
    print(traceback.print_tb(e.__traceback__))

我正在使用Python 3.7。

对于Python 3.5+：

因此，您可以从您的异常以及其他任何异常中获取stacktrace。使用traceback.TracebackException它（只需更换ex您的除外）：

print("".join(traceback.TracebackException.from_exception(ex).format())

一个扩展的示例和其他功能可以做到这一点：

import traceback

try:
    1/0
except Exception as ex:
    print("".join(traceback.TracebackException.from_exception(ex).format()) == traceback.format_exc() == "".join(traceback.format_exception(type(ex), ex, ex.__traceback__))) # This is True !!
    print("".join(traceback.TracebackException.from_exception(ex).format()))

输出将是这样的：

True
Traceback (most recent call last):
  File "untidsfsdfsdftled.py", line 29, in <module>
    1/0
ZeroDivisionError: division by zero

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))

如果您的目标是使异常和stacktrace消息看起来完全像python引发错误时一样，则以下内容在python 2 + 3中均适用：

import sys, traceback


def format_stacktrace():
    parts = ["Traceback (most recent call last):\n"]
    parts.extend(traceback.format_stack(limit=25)[:-2])
    parts.extend(traceback.format_exception(*sys.exc_info())[1:])
    return "".join(parts)

# EXAMPLE BELOW...

def a():
    b()


def b():
    c()


def c():
    d()


def d():
    assert False, "Noooh don't do it."


print("THIS IS THE FORMATTED STRING")
print("============================\n")

try:
    a()
except:
    stacktrace = format_stacktrace()
    print(stacktrace)

print("THIS IS HOW PYTHON DOES IT")
print("==========================\n")
a()

它通过format_stacktrace()从堆栈中删除最后一个调用并加入其余调用来工作。运行时，以上示例给出以下输出：

THIS IS THE FORMATTED STRING
============================

Traceback (most recent call last):
  File "test.py", line 31, in <module>
    a()
  File "test.py", line 12, in a
    b()
  File "test.py", line 16, in b
    c()
  File "test.py", line 20, in c
    d()
  File "test.py", line 24, in d
    assert False, "Noooh don't do it."
AssertionError: Noooh don't do it.

THIS IS HOW PYTHON DOES IT
==========================

Traceback (most recent call last):
  File "test.py", line 38, in <module>
    a()
  File "test.py", line 12, in a
    b()
  File "test.py", line 16, in b
    c()
  File "test.py", line 20, in c
    d()
  File "test.py", line 24, in d
    assert False, "Noooh don't do it."
AssertionError: Noooh don't do it.

我定义了以下帮助程序类：

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

我以后可以这样使用：

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

以后可以像这样消费它：

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

（背景：我很沮丧，因为将Promises与s一起使用Exception，不幸的是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进行回溯）