Question

我正在尝试诊断我的自定义中间件中的错误以某种方式关闭我的会话中间件。自定义中间件是一个简单的应用程序，它删除某些文件夹中的旧文件。

class DeleteMediaMiddleware(object):
    time_limit = 100.

    def check_folder(self,folder):
    '''Deletes the files older than "time_limit" '''
        os.chdir(folder)
        files_in_folder = os.listdir(os.curdir)
        for my_file in files_in_folder:
            creation_time = os.path.getmtime(my_file)
            file_lifetime = time.time() - creation_time
            if file_lifetime > self.time_limit:
                os.remove(my_file)

    def process_request(self, request):
    '''Standard middleware method which runs on every request'''
        self.check_folder(config.input_folder)
        self.check_folder(config.output_folder)
        self.check_folder(config.plot_folder)
        self.check_folder(config.report_folder)
    return None

它位于Django项目文件夹中。（这些级别是Django默认创建的。在我的例子中，项目名为expofit，文件夹结构是expofit / expofit）

project_folder_lvl1/project_folder_lvl2/mymiddleware.py

我将中间件添加到Djagno设置：

MIDDLEWARE_CLASSES = (
    'django.middleware.common.CommonMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'server.mymiddleware.DeleteMediaMiddleware',
    )

然而，我最终得到了一个错误。

Exception Value:    no such table: django_session

来自于检查views.py中的会话值：

....    
if request.session.has_key('user_id'):
....

只要我在Django设置中禁用我的中间件，一切正常。

更新：

我成功地打开了数据库，这是一个位于project_folder_lvl1中的sqlite文件，找到了无法访问的表。

这是完整的Django追溯。

Environment:

Request Method: GET
Request URL: http://localhost:8000/expofit/

Django Version: 1.4.1
Python Version: 2.7.3
Installed Applications:
('django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'expofit_django_app',
'south',
'django.contrib.admin')
Installed Middleware:
('django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'server.mymiddleware.DeleteMediaMiddleware')


Traceback:
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
111.                         response = callback(request, *callback_args, **callback_kwargs)
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/views/decorators/csrf.py" in wrapped_view
77.         return view_func(*args, **kwargs)
File "/home/alan/Desktop/expofit/expofit_hg/py/server/expofit_django_app/views.py" in check
59.         return view(request, *args, **kwargs)
File "/home/alan/Desktop/expofit/expofit_hg/py/server/expofit_django_app/views.py" in start
23.     if request.session.has_key('user_id'):
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/contrib/sessions/backends/base.py" in has_key
103.         return key in self._session
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/contrib/sessions/backends/base.py" in _get_session
165.                 self._session_cache = self.load()
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/contrib/sessions/backends/db.py" in load
19.                 expire_date__gt=timezone.now()
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/db/models/manager.py" in get
131.         return self.get_query_set().get(*args, **kwargs)
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/db/models/query.py" in get
361.         num = len(clone)
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/db/models/query.py" in __len__
85.                 self._result_cache = list(self.iterator())
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/db/models/query.py" in iterator
291.         for row in compiler.results_iter():
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in results_iter
763.         for rows in self.execute_sql(MULTI):
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py" in execute_sql
818.         cursor.execute(sql, params)
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/db/backends/util.py" in execute
40.             return self.cursor.execute(sql, params)
File "/home/alan/Desktop/expofit/expofit_env/local/lib/python2.7/site-packages/django/db/backends/sqlite3/base.py" in execute
337.             return Database.Cursor.execute(self, query, params)

Exception Type: DatabaseError at /expofit/
Exception Value: no such table: django_session

寻找有关如何调试此问题的想法？

Answer 1

通过添加sqlite数据库的绝对路径来解决问题。

settings.py产生了错误：

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': 'expofit_database',  
        ...
        ...

new settings.py:

PROJECT_PATH = os.path.realpath(os.path.dirname(__file__))
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join( PROJECT_PATH, 'expofit_database'),  
        ...
        ...

从我的想法来看，问题在于调用

os.chdir(folder)

在check_folder函数内部，它搞乱了运行时路径。虽然设置绝对路径解决了访问数据库的问题，但我删除了os.chdir（文件夹）以防止将来发生潜在错误。

def check_folder(folder):
    time_limit = 100.
    files_in_folder = os.listdir(folder)
    for file_name in files_in_folder:
        file_path = os.path.join(folder,file_name)
        creation_time = os.path.getmtime(file_path)
        file_lifetime = time.time() - creation_time
        if file_lifetime > time_limit:
            os.remove(file_path)

Django自定义中间件混淆会话中间件

1 个答案: