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    Question A question about the Middleware module "djangodblog" and its "DBLogMiddleware" class


    Hello everybody


    Currently I'm learning python Web development by Django and I'm reading James McGaw' book: "Beginning Django E-Commerce" (Apress Edition).

    So far, I've followed step by step the instructions given in the book and everything worked pretty well:

    - installation of Django, MySQL,

    - creation of the Django specific database tabes while I run
    Code:
    $ python -tt manage.py syncdb
    - starting the server
    Code:
    $ python -tt manage.py runserver
    I opened firefox and I saw the message "It worked!" while I entered the url "http://127.0.0.1:8000/" which indicated that the server was running ready to receive requests.

    Yet, things became more complicated when in the next chapter we started creating an application. I changed the content of the following files

    - settings.py
    - urls.py

    and also creating the corresponding HTML files according to the directory hierarchy described in the book for the templates. After following step by step instructions in the book, I stoped and restarted the server with the new URL of the application, I got the following message on the browser
    Code:
    A server error occurred.  Please contact the administrator.
    And on the terminal, where I had run the command to start the server I saw the following exception StackTrace
    Code:
    $  python -tt manage.py runserver
    Validating models...
    
    0 errors found
    Django version 1.4.2, using settings 'ecomstore.settings'
    Development server is running at http://127.0.0.1:8000/
    Quit the server with CONTROL-C.
    Traceback (most recent call last):
      File "/usr/lib64/python2.7/wsgiref/handlers.py", line 85, in run
        self.result = application(self.environ, self.start_response)
      File "/usr/lib/python2.7/site-packages/django/contrib/staticfiles/handlers.py", line 67, in __call__
        return self.application(environ, start_response)
      File "/usr/lib/python2.7/site-packages/django/core/handlers/wsgi.py", line 219, in __call__
        self.load_middleware()
      File "/usr/lib/python2.7/site-packages/django/core/handlers/base.py", line 51, in load_middleware
        raise exceptions.ImproperlyConfigured('Middleware module "%s" does not define a "%s" class' % (mw_module, mw_classname))
    ImproperlyConfigured: Middleware module "djangodblog" does not define a "DBLogMiddleware" class
    [17/Dec/2012 08:27:27] "GET / HTTP/1.1" 500 59

    Any idea about this error? What causes this problem?

    Thanks in advance,

    Regards,
    Dariyoosh



    In the case where it might be helpful here is the content of the file settings.py of the project:

    Code:
    # Django settings for ecomstore project.
    
    DEBUG = True
    TEMPLATE_DEBUG = DEBUG
    
    ADMINS = (
        # ('Your Name', 'your_email@example.com'),
    )
    
    MANAGERS = ADMINS
    
    DATABASES = {
        'default': {
            'ENGINE': 'django.db.backends.mysql', # Add 'postgresql_psycopg2', 'mysql', 'sqlite3' or 'oracle'.
            'NAME': 'ecomstore',                  # Or path to database file if using sqlite3.
            'USER': 'train2012',                  # Not used with sqlite3.
            'PASSWORD': '******',              # Not used with sqlite3.
            'HOST': '',                      # Set to empty string for localhost. Not used with sqlite3.
            'PORT': '',                      # Set to empty string for default. Not used with sqlite3.
        }
    }
    
    # Local time zone for this installation. Choices can be found here:
    # http://en.wikipedia.org/wiki/List_of_tz_zones_by_name
    # although not all choices may be available on all operating systems.
    # In a Windows environment this must be set to your system time zone.
    TIME_ZONE = 'America/Chicago'
    
    # Language code for this installation. All choices can be found here:
    # http://www.i18nguy.com/unicode/language-identifiers.html
    LANGUAGE_CODE = 'en-us'
    
    SITE_ID = 1
    
    # If you set this to False, Django will make some optimizations so as not
    # to load the internationalization machinery.
    USE_I18N = True
    
    # If you set this to False, Django will not format dates, numbers and
    # calendars according to the current locale.
    USE_L10N = True
    
    # If you set this to False, Django will not use timezone-aware datetimes.
    USE_TZ = True
    
    # Absolute filesystem path to the directory that will hold user-uploaded files.
    # Example: "/home/media/media.lawrence.com/media/"
    MEDIA_ROOT = ''
    
    # URL that handles the media served from MEDIA_ROOT. Make sure to use a
    # trailing slash.
    # Examples: "http://media.lawrence.com/media/", "http://example.com/media/"
    MEDIA_URL = ''
    
    # Absolute path to the directory static files should be collected to.
    # Don't put anything in this directory yourself; store your static files
    # in apps' "static/" subdirectories and in STATICFILES_DIRS.
    # Example: "/home/media/media.lawrence.com/static/"
    STATIC_ROOT = ''
    
    # URL prefix for static files.
    # Example: "http://media.lawrence.com/static/"
    STATIC_URL = '/static/'
    
    # Additional locations of static files
    STATICFILES_DIRS = (
        # Put strings here, like "/home/html/static" or "C:/www/django/static".
        # Always use forward slashes, even on Windows.
        # Don't forget to use absolute paths, not relative paths.
    )
    
    # List of finder classes that know how to find static files in
    # various locations.
    STATICFILES_FINDERS = (
        'django.contrib.staticfiles.finders.FileSystemFinder',
        'django.contrib.staticfiles.finders.AppDirectoriesFinder',
    #    'django.contrib.staticfiles.finders.DefaultStorageFinder',
    )
    
    # Make this unique, and don't share it with anybody.
    SECRET_KEY = '&fz4^s88*14s3k0muuoo9zj1@9(@_-zp*ncwflqjxdhn%ja4q)'
    
    # List of callables that know how to import templates from various sources.
    TEMPLATE_LOADERS = (
        'django.template.loaders.filesystem.Loader',
        'django.template.loaders.app_directories.Loader',
    #     'django.template.loaders.eggs.Loader',
    )
    
    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',
        # Uncomment the next line for simple clickjacking protection:
        # 'django.middleware.clickjacking.XFrameOptionsMiddleware',
        'djangodblog.DBLogMiddleware',
    )
    
    ROOT_URLCONF = 'ecomstore.urls'
    
    # Python dotted path to the WSGI application used by Django's runserver.
    WSGI_APPLICATION = 'ecomstore.wsgi.application'
    
    TEMPLATE_DIRS = (
        # Put strings here, like "/home/html/django_templates" or "C:/www/django/templates".
        # Always use forward slashes, even on Windows.
        # Don't forget to use absolute paths, not relative paths.
        '/home/train2012/Documents/Python/Django/books/Apress_Beginning_Django_Ecommerce/ecomstore/templates',
    )
    
    INSTALLED_APPS = (
        #'django.contrib.auth',
        #'django.contrib.contenttypes',
        #'django.contrib.sessions',
        #'django.contrib.sites',
        #'django.contrib.messages',
        #'django.contrib.staticfiles',
        # Uncomment the next line to enable the admin:
        # 'django.contrib.admin',
        # Uncomment the next line to enable admin documentation:
        # 'django.contrib.admindocs',
       'djangodblog',
    )
    
    # A sample logging configuration. The only tangible logging
    # performed by this configuration is to send an email to
    # the site admins on every HTTP 500 error when DEBUG=False.
    # See http://docs.djangoproject.com/en/dev/topics/logging for
    # more details on how to customize your logging configuration.
    LOGGING = {
        'version': 1,
        'disable_existing_loggers': False,
        'filters': {
            'require_debug_false': {
                '()': 'django.utils.log.RequireDebugFalse'
            }
        },
        'handlers': {
            'mail_admins': {
                'level': 'ERROR',
                'filters': ['require_debug_false'],
                'class': 'django.utils.log.AdminEmailHandler'
            }
        },
        'loggers': {
            'django.request': {
                'handlers': ['mail_admins'],
                'level': 'ERROR',
                'propagate': True,
            },
        }
    }
  2. #2
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    Devshed Newbie (0 - 499 posts)

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    Ok, finally I found the answer myself (after a long research)

    Instead of writing
    Code:
    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',
        # Uncomment the next line for simple clickjacking protection:
        # 'django.middleware.clickjacking.XFrameOptionsMiddleware',
        'djangodblog.DBLogMiddleware',
    )
    I had to write the following in settings.py in order to solve the problem

    Code:
    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',
        # Uncomment the next line for simple clickjacking protection:
        # 'django.middleware.clickjacking.XFrameOptionsMiddleware',
        #'djangodblog.DBLogMiddleware',
        'djangodblog.middleware.DBLogMiddleware',
    )
    I hope this may help those who have encountered the same problem.


    Regards,
    Dariyoosh

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