Flask快速入门(17) — flask_session
作用：将默认保存的签名cookie中的值，保存到 redis/memcached/file/Mongodb/SQLAlchemy
安装：pip install flask-session
使用1：
from flask import Flask,session
from flask_session import RedisSessionInterface
import redis
app = Flask(__name__)
conn=redis.Redis(host='127.0.0.1',port=6379) # 连接redis
# use_signer是否对key签名
# 如果use_siginer为False,这表示不需要配置app.secret_key
app.session_interface=RedisSessionInterface(conn,key_prefix='lqz')
@app.route('/')
def hello_world():
session['name']='lqz'
return 'Hello World!'
if __name__ == '__main__':
app.run()我们知道session是从app.session_interface入口。所以要改变存储位置的话，要重写app.session_interface。在这里的RedisSessionInterface重写了open_session（取）和save_session(存)。我们来看看RedisSessionInterface这个类
class RedisSessionInterface(SessionInterface):
serializer = pickle
session_class = RedisSession
# 实例化参数：redis连接的redis; key_prefix存储的前缀; user_signer是否对key签名，为False则不需要设置secret_key,为True时，需要设置; permanent关闭浏览器是否保存，为Frue保存，为False不保存
def __init__(self, redis, key_prefix, use_signer=False, permanent=True):
if redis is None:
from redis import Redis
redis = Redis()
self.redis = redis
self.key_prefix = key_prefix
self.use_signer = use_signer
self.permanent = permanent
def open_session(self, app, request):
sid = request.cookies.get(app.session_cookie_name)
if not sid:
sid = self._generate_sid()
return self.session_class(sid=sid, permanent=self.permanent)
if self.use_signer:
signer = self._get_signer(app)
if signer is None:
return None
try:
sid_as_bytes = signer.unsign(sid)
sid = sid_as_bytes.decode()
except BadSignature:
sid = self._generate_sid()
return self.session_class(sid=sid, permanent=self.permanent)
if not PY2 and not isinstance(sid, text_type):
sid = sid.decode('utf-8', 'strict')
val = self.redis.get(self.key_prefix + sid) # 从redis中取出session
if val is not None:
try:
data = self.serializer.loads(val) # 获取session反序列化值
return self.session_class(data, sid=sid)
except:
return self.session_class(sid=sid, permanent=self.permanent)
return self.session_class(sid=sid, permanent=self.permanent)
def save_session(self, app, session, response):
domain = self.get_cookie_domain(app)
path = self.get_cookie_path(app)
if not session:
if session.modified:
self.redis.delete(self.key_prefix + session.sid)
response.delete_cookie(app.session_cookie_name,
domain=domain, path=path)
return
httponly = self.get_cookie_httponly(app)
secure = self.get_cookie_secure(app)
expires = self.get_expiration_time(app, session)
val = self.serializer.dumps(dict(session)) # 将session序列化放入val中
# 将session设置到redis,name=前缀+字符串，value=session值
self.redis.setex(name=self.key_prefix + session.sid, value=val,
time=total_seconds(app.permanent_session_lifetime))
if self.use_signer:
session_id = self._get_signer(app).sign(want_bytes(session.sid))
else:
session_id = session.sid
response.set_cookie(app.session_cookie_name, session_id,
expires=expires, httponly=httponly,
domain=domain, path=path, secure=secure)使用2：
from flask import Flask,session
from redis import Redis
from flask_session import Session
app = Flask(__name__)
app.config['SESSION_TYPE'] = 'redis'
app.config['SESSION_REDIS'] = Redis(host='127.0.0.1',port='6379')
Session(app)
@app.route('/')
def index():
session['name'] = 'nick'
return 'hello'
@app.route('/index')
def test():
return session['name']
if __name__ == '__main__':
app.run()主要是通过配置SESSION_TYPE源码中进行相应的存储：Session(app)源码
def __init__(self, app=None):
self.app = app
if app is not None:
self.init_app(app)self.init_app(app)源码：
def init_app(self, app):
app.session_interface = self._get_interface(app) # 在这里重写了session_interfaceself._get_interface(app)源码：
def _get_interface(self, app):
# 在这里做了一些相关的配置
config = app.config.copy()
config.setdefault('SESSION_TYPE', 'null')
config.setdefault('SESSION_PERMANENT', True)
config.setdefault('SESSION_USE_SIGNER', False)
config.setdefault('SESSION_KEY_PREFIX', 'session:')
config.setdefault('SESSION_REDIS', None)
config.setdefault('SESSION_MEMCACHED', None)
config.setdefault('SESSION_FILE_DIR',
os.path.join(os.getcwd(), 'flask_session'))
config.setdefault('SESSION_FILE_THRESHOLD', 500)
config.setdefault('SESSION_FILE_MODE', 384)
config.setdefault('SESSION_MONGODB', None)
config.setdefault('SESSION_MONGODB_DB', 'flask_session')
config.setdefault('SESSION_MONGODB_COLLECT', 'sessions')
config.setdefault('SESSION_SQLALCHEMY', None)
config.setdefault('SESSION_SQLALCHEMY_TABLE', 'sessions')
# 通过if...elif...else来判断匹配config['SESSION_TYPE']，再执行相应的session_interface
if config['SESSION_TYPE'] == 'redis':
session_interface = RedisSessionInterface(
config['SESSION_REDIS'], config['SESSION_KEY_PREFIX'],
config['SESSION_USE_SIGNER'], config['SESSION_PERMANENT'])
elif config['SESSION_TYPE'] == 'memcached':
session_interface = MemcachedSessionInterface(
config['SESSION_MEMCACHED'], config['SESSION_KEY_PREFIX'],
config['SESSION_USE_SIGNER'], config['SESSION_PERMANENT'])
elif config['SESSION_TYPE'] == 'filesystem':
session_interface = FileSystemSessionInterface(
config['SESSION_FILE_DIR'], config['SESSION_FILE_THRESHOLD'],
config['SESSION_FILE_MODE'], config['SESSION_KEY_PREFIX'],
config['SESSION_USE_SIGNER'], config['SESSION_PERMANENT'])
elif config['SESSION_TYPE'] == 'mongodb':
session_interface = MongoDBSessionInterface(
config['SESSION_MONGODB'], config['SESSION_MONGODB_DB'],
config['SESSION_MONGODB_COLLECT'],
config['SESSION_KEY_PREFIX'], config['SESSION_USE_SIGNER'],
config['SESSION_PERMANENT'])
elif config['SESSION_TYPE'] == 'sqlalchemy':
session_interface = SqlAlchemySessionInterface(
app, config['SESSION_SQLALCHEMY'],
config['SESSION_SQLALCHEMY_TABLE'],
config['SESSION_KEY_PREFIX'], config['SESSION_USE_SIGNER'],
config['SESSION_PERMANENT'])
else:
session_interface = NullSessionInterface()
return session_interface问题：设置cookie时，如何设定关闭浏览器则cookie失效。
response.set_cookie('k','v',exipre=None)#这样设置即可
#在session中设置
app.session_interface=RedisSessionInterface(conn,key_prefix='lqz',permanent=False)
#一般不用，我们一般都设置超时时间，多长时间后失效问题：cookie默认超时时间是多少？如何设置超时时间
#源码expires = self.get_expiration_time(app, session)
'PERMANENT_SESSION_LIFETIME': timedelta(days=31),#这个配置文件控制