python-django中间件session源码

settings.py

MIDDLEWARE = [
'django.contrib.sessions.middleware.SessionMiddleware',
]

① 看看SessionMiddleware类? ?from django.contrib.sessions.middleware import SessionMiddleware

class SessionMiddleware(MiddlewareMixin):

　　 #1.1
def __init__(self, get_response=None):
    self.get_response = get_response
    engine = import_module(settings.SESSION_ENGINE)
    self.SessionStore = engine.SessionStore
　　 #2
def process_request(self, request):
    session_key = request.COOKIES.get(settings.SESSION_COOKIE_NAME)
    request.session = self.SessionStore(session_key)

def process_response(self, request, response):
    """
    If request.session was modified, or if the configuration is to save the
    session every time, save the changes and set a session cookie or delete
    the session cookie if the session has been emptied.
    """
    try:
        accessed = request.session.accessed
        modified = request.session.modified
        empty = request.session.is_empty()
    except AttributeError:
        pass
    else:
        # First check if we need to delete this cookie.
        # The session should be deleted only if the session is entirely empty
        if settings.SESSION_COOKIE_NAME in request.COOKIES and empty:
            response.delete_cookie(
                settings.SESSION_COOKIE_NAME,
                path=settings.SESSION_COOKIE_PATH,
                domain=settings.SESSION_COOKIE_DOMAIN,
            )
        else:
            if accessed:
                patch_vary_headers(response, ('Cookie',))
            if (modified or settings.SESSION_SAVE_EVERY_REQUEST) and not empty:
                if request.session.get_expire_at_browser_close():
                    max_age = None
                    expires = None
                else:
                    max_age = request.session.get_expiry_age()
                    expires_time = time.time() + max_age
                    expires = cookie_date(expires_time)
                # Save the session data and refresh the client cookie.
                # Skip session save for 500 responses, refs #3881.
                if response.status_code != 500:
                    try:
                        request.session.save()
                    except UpdateError:
                        raise SuspiciousOperation(
                            "The request's session was deleted before the "
                            "request completed. The user may have logged "
                            "out in a concurrent request, for example."
                        )
                    response.set_cookie(
                        settings.SESSION_COOKIE_NAME,
                        request.session.session_key, max_age=max_age,
                        expires=expires, domain=settings.SESSION_COOKIE_DOMAIN,
                        path=settings.SESSION_COOKIE_PATH,
                        secure=settings.SESSION_COOKIE_SECURE or None,
                        httponly=settings.SESSION_COOKIE_HTTPONLY or None,
                    )
    return response

①1步：每个中间件的类在调用的时候都会先执行init 构造方法

class SessionMiddleware(MiddlewareMixin):
def __init__(self, get_response=None):
    self.get_response = get_response
    #1.1.1 到配置文件中获取一个类
    engine = import_module(settings.SESSION_ENGINE)
    self.SessionStore = engine.SessionStore

①1.1步：django自带的settings中没有SESSION_ENGINE这个属性,那就需要去全局的global_settings文件中找

    SESSION_ENGINE = 'django.contrib.sessions.backends.db'     #这个时候self.SessionStore =db 文件中的 SessionStore类

class SessionStore(SessionBase):
"""
Implements database session store.
"""
def __init__(self, session_key=None):
    super(SessionStore, self).__init__(session_key)

@classmethod
def get_model_class(cls):
    # Avoids a circular import and allows importing SessionStore when
    # django.contrib.sessions is not in INSTALLED_APPS.
    from django.contrib.sessions.models import Session
    return Session

@cached_property
def model(self):
    return self.get_model_class()

def load(self):
    try:
        s = self.model.objects.get(
            session_key=self.session_key,
            expire_date__gt=timezone.now()
        )
        return self.decode(s.session_data)
    except (self.model.DoesNotExist, SuspiciousOperation) as e:
        if isinstance(e, SuspiciousOperation):
            logger = logging.getLogger('django.security.%s' % e.__class__.__name__)
            logger.warning(force_text(e))
        self._session_key = None
        return {}

def exists(self, session_key):
    return self.model.objects.filter(session_key=session_key).exists()

def create(self):
    while True:
        self._session_key = self._get_new_session_key()
        try:
            # Save immediately to ensure we have a unique entry in the
            # database.
            self.save(must_create=True)
        except CreateError:
            # Key wasn't unique. Try again.
            continue
        self.modified = True
        return

def create_model_instance(self, data):
    """
    Return a new instance of the session model object, which represents the
    current session state. Intended to be used for saving the session data
    to the database.
    """
    return self.model(
        session_key=self._get_or_create_session_key(),
        session_data=self.encode(data),
        expire_date=self.get_expiry_date(),
    )

def save(self, must_create=False):
    """
    Saves the current session data to the database. If 'must_create' is
    True, a database error will be raised if the saving operation doesn't
    create a *new* entry (as opposed to possibly updating an existing
    entry).
    """
    if self.session_key is None:
        return self.create()
    data = self._get_session(no_load=must_create)
    obj = self.create_model_instance(data)
    using = router.db_for_write(self.model, instance=obj)
    try:
        with transaction.atomic(using=using):
            obj.save(force_insert=must_create, force_update=not must_create, using=using)
    except IntegrityError:
        if must_create:
            raise CreateError
        raise
    except DatabaseError:
        if not must_create:
            raise UpdateError
        raise

def delete(self, session_key=None):
    if session_key is None:
        if self.session_key is None:
            return
        session_key = self.session_key
    try:
        self.model.objects.get(session_key=session_key).delete()
    except self.model.DoesNotExist:
        pass

@classmethod
def clear_expired(cls):
    cls.get_model_class().objects.filter(expire_date__lt=timezone.now()).delete()

SessionStore类

以上就是源利百科网小编为大家整理的python-django中间件session源码相关主题介绍,如果您觉得小编更新的文章只要能对粉丝们有用，就是我们最大的鼓励和动力,不要忘记讲本站分享给您身边的朋友哦！！