如何使用python和Google AppEngine编写或创建文件(如果不存在)

问题描述：

这是我的代码:

f = open('text/a.log', 'wb')
f.write('hahaha')
f.close()

它不存在时不会创建新文件

and it is not create a new file when not exist

如何做到这一点，

谢谢

已更新

class MyThread(threading.Thread):
    def run(self):
        f = open('a.log', 'w')
        f.write('hahaha')
        f.close()

错误是:

Traceback (most recent call last):
  File "D:\Python25\lib\threading.py", line 486, in __bootstrap_inner
    self.run()
  File "D:\zjm_code\helloworld\views.py", line 15, in run
    f = open('a.log', 'w')
  File "d:\Program Files\Google\google_appengine\google\appengine\tools\dev_appserver.py", line 1188, in __init__
    raise IOError('invalid mode: %s' % mode)
IOError: invalid mode: w

答

由于Google Appengine不允许您写入文件

Its because of google appengine not allowed you to write files

它的定义是这样的

ALLOWED_MODES = frozenset(['r', 'rb', 'U', 'rU'])

和

if mode not in FakeFile.ALLOWED_MODES:
  raise IOError('invalid mode: %s' % mode)

_{注意:"U"是通用换行模式， http://docs.python.org/library/io.html#io.open}

_{Note: 'U' is universal newline mode, http://docs.python.org/library/io.html#io.open}

修改:您可能会对Google AppEngine 登录感兴趣>他们文档中的会话

Edit: You might interest Google AppEngine Logging session in their documents

示例

import logging
....
logging.error('There was an error retrieving ...')
logging.debug('Finish something')

如何使用python和Google AppEngine编写或创建文件(如果不存在)

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