django session做注册遇到的问题

 

今天注册功能遇到个问题。验证码不正确，但是我他妈输入的是正确的验证码啊，我本地测试是好的啊，为什么显示不行呢？更蛋疼的是，有的时候是好的，有的时候不行，nmb。

跟源码

• 验证码的实现过程

  def get(self, request, *args, **kwargs):
        """
        获取验证码
        ---
        """
        uid = str(uuid.uuid4())
        mp_src = hashlib.md5(uid.encode("UTF-8")).hexdigest()
        text = mp_src[0:4]
        request.session["captcha_code"] = text
        request.session.save()
        font_path = current_path + "/www/static/www/fonts/Vera.ttf"
        logger.debug("======> font path " + str(font_path))
        font = ImageFont.truetype(font_path, 22)
  
        size = self.getsize(font, text)
        size = (size[0] * 2, int(size[1] * 1.4))
  
        image = Image.new('RGBA', size)
  
        try:
            PIL_VERSION = int(NON_DIGITS_RX.sub('', Image.VERSION))
        except:
            PIL_VERSION = 116
        xpos = 2
  
        charlist = []
        for char in text:
            charlist.append(char)
  
        for char in charlist:
            fgimage = Image.new('RGB', size, '#001100')
            charimage = Image.new('L', self.getsize(font, ' %s ' % char), '#000000')
            chardraw = ImageDraw.Draw(charimage)
            chardraw.text((0, 0), ' %s ' % char, font=font, fill='#ffffff')
            if PIL_VERSION >= 116:
                charimage = charimage.rotate(random.randrange(*(-35, 35)), expand=0, resample=Image.BICUBIC)
            else:
                charimage = charimage.rotate(random.randrange(*(-35, 35)), resample=Image.BICUBIC)
            charimage = charimage.crop(charimage.getbbox())
            maskimage = Image.new('L', size)
  
            maskimage.paste(charimage, (xpos, from_top, xpos + charimage.size[0], from_top + charimage.size[1]))
            size = maskimage.size
            image = Image.composite(fgimage, image, maskimage)
            xpos = xpos + 2 + charimage.size[0]
  
        image = image.crop((0, 0, xpos + 1, size[1]))
  
        ImageDraw.Draw(image)
  
        out = StringIO()
        image.save(out, "PNG")
        out.seek(0)
  
        response = HttpResponse(content_type='image/png')
        response.write(out.read())
        response['Content-length'] = out.tell()
  
        return response
  

  　　

  整个实现过程比较简单，跟常见的验证码实现方式一样。这里主要用到了python的 PIL 用于生成图片。生成随机验证码后将验证码保存在session里 

  request.session["captcha_code"] = text。

   

• 验证码的校验过程

  real_captcha_code = request.session.get("captcha_code")
  
  if real_captcha_code is None or captcha_code is None or real_captcha_code.lower() != captcha_code.lower():
    raise forms.ValidationError(
        self.error_messages['captcha_code_error'],
        code='captcha_code_error'
    )
  

  　　

整个过程没有什么问题，本地运行也666。但是打包到容器运行失败（公司采用docker方式运行应用）。

填坑

• session和cookie

  session和cookie，session是保存在服务器端，cookie存储在浏览器上，我们称为客户端，客户端向服务端发送请求时，会将cookie一起发送给服务端。服务端接收到请求后，会去检查是否已经有该客户端的session信息，如果没有，则创建一个新的session对象，用于保存客户端的一些必要信息，如果从服务器上找到了该客户端的信息，则会将该信息加载到session里

• django session相关配置

# Cache to store session data if using the cache session backend.
SESSION_CACHE_ALIAS = 'default'  # 这个值对应CACHES里面的key
# Cookie name. This can be whatever you want.
SESSION_COOKIE_NAME = 'sessionid'
# The module to store session data
SESSION_ENGINE = 'django.contrib.sessions.backends.db'
# class to serialize session data
SESSION_SERIALIZER = 'django.contrib.sessions.serializers.JSONSerializer'

#########
# CACHE #
#########

# The cache backends to use.
CACHES = {
    'default': {
        'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
    }
}

　　

使用django的session机制需要在settings文件中添加如下配置

   中间件配置

MIDDLEWARE_CLASSES = (
    ......
    'django.contrib.sessions.middleware.SessionMiddleware',
    ...... 
)

　　

安装app配置

INSTALLED_APPS = ('django.contrib.sessions',)

　　

添加配置后使用python manage.py migrate 会在数据库生成对应的数据表。

我发现我们项目中处理的时候自定义了配置里的SESSION_ENGINE属性。

SESSION_ENGINE = "www.contrib.sessions.backends.cache"
SESSION_CACHE_ALIAS = 'session'
SESSION_COOKIE_DOMAIN = '.goodrain.com'
SESSION_COOKIE_AGE = 3600

　　

• 关于django session的SESSION_ENGINE

  SESSION_ENGINE的主要配置有5个。

  • 缓存类配置django.contrib.sessions.backends.cache

  Set SESSION_ENGINE to "django.contrib.sessions.backends.cache" for a simple caching session store. Session data will be stored directly in your cache. However, session data may not be persistent: cached data can be evicted if the cache fills up or if the cache server is restarted.

  • 缓存类加持久化配置 django.contrib.sessions.backends.cached_db

  For persistent, cached data, set SESSION_ENGINE to "django.contrib.sessions.backends.cached_db". This uses a write-through cache -- every write to the cache will also be written to the database. Session reads only use the database if the data is not already in the cache.

  • 数据库持久化配置 django.contrib.sessions.backends.db 默认方式

  Once you have configured your installation, run manage.py migrateto install the single database table that stores session data.

  • 文件存放session配置 django.contrib.sessions.backends.file

  To use file-based sessions, set the SESSION_ENGINE setting to"django.contrib.sessions.backends.file".

  You might also want to set the SESSION_FILE_PATH setting (which defaults to output from tempfile.gettempdir(), most likely /tmp) to control where Django stores session files. Be sure to check that your Web server has permissions to read and write to this location.

  • 基于cookie的session配置 django.contrib.sessions.backends.signed_cookies

  To use cookies-based sessions, set the SESSION_ENGINE setting to"django.contrib.sessions.backends.signed_cookies". The session data will be stored using Django's tools for cryptographic signing and the SECRET_KEY setting.

  详细可以参看这里

  我发现我们的SESSION_ENGINE被自定义过。代码如下

  from django.contrib.sessions.backends.cache import SessionStore as BaseSessionStore
  
  import logging
  logger = logging.getLogger('default')
  
  class SessionStore(BaseSessionStore):
  
    def load(self):
        try:
            logger.debug('session', 'start load key {}'.format(self.cache_key))
            session_data = self._cache.get(self.cache_key, None)
        except Exception, e:
            logger.error('session', 'load key {} error.'.format(self.cache_key))
            logger.exception('session', e)
            # Some backends (e.g. memcache) raise an exception on invalid
            # cache keys. If this happens, reset the session. See #17810.
            session_data = None
        if session_data is not None:
            logger.debug('session', 'got data for key {}: {}'.format(self.cache_key, session_data))
            return session_data
        self.create()
        return {}
  

  　　

  这段代码其实没有什么好讲的。只是继承了原有的 django.contrib.sessions.backends.cache 的 SessionStore 类，然后copy原有的load方法加上了logger。

• 填坑记

  1. 在生成验证码的时候加上一句代码

     request.session.save()

      

     结果不管用

  2. 将配置里 SESSION_ENGINE 去掉，则会使用默认的  django.contrib.sessions.backends.db  。结果成功。

小记

原因没找到，乱改很折腾。