我正在使用带有sqlalchemy的cherrypy来构建一个无头（只有CLI客户端）的restful服务器。
我使用以下方法将sqlalchemy绑定到cherrypy引擎：https://bitbucket.org/Lawouach/cherrypy-recipes/src/c8290261eefb/web/database/sql_alchemy/ 如果数据库不存在，则会略微修改recipe以构建数据库。
服务器公开了几个uri，例如客户端，文章，商店......
我打算将装饰器 popargs 与 _cp_dispatch 一起使用，以便在处理之前将我的资源名称转换为其ID。我使用 cherrypy.dispatch.MethodDispatcher 作为调度程序（所以我可以编写GET / POST / PUT / DELETE方法）
我可以从任何GET / POST / PUT / DELETE方法访问该插件，但我无法从_cp_dispatch访问它。
在进入GET / POST / PUT / DELETE方法之前，我知道如何将资源名称转换为他们的id？
这是我的问题的复制品
$ tree
.
├── __init__.py
├── models.py
├── my.db
├── root.py
├── saplugin.py
├── saplugin.py.original
└── satool.py
我的sqlalchemy模型（我有几个，只有一个是重现问题所必需的）
$ cat models.py
# -*- coding: utf-8 -*-
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy import Column, Integer, String
Base = declarative_base()
class User(Base):
__tablename__ = 'users'
id = Column(Integer, primary_key=True)
name = Column(String)
这是服务器的主要脚本
$ cat root.py
# -*- coding: utf-8 -*-
import cherrypy
from models import User
from saplugin import SAEnginePlugin
from satool import SATool
def name_to_id(param, table):
if not param.isdigit():
param = cherrypy.request.db.query(table.id).\
filter(table.name == param).one()
return param
class Root(object):
exposed = True
def __init__(self):
self.users = Users()
def GET(self):
# Get the SQLAlchemy session associated
# with this request.
# It'll be released once the request
# processing terminates
return "Hello World"
class Users(object):
exposed = True
@cherrypy.popargs('user_id')
def GET(self, user_id=None, **kwargs):
user_id = name_to_id(user_id, User)
return "I'm resource %s" % user_id
if __name__ == '__main__':
# Register the SQLAlchemy plugin
SAEnginePlugin(cherrypy.engine).subscribe()
# Register the SQLAlchemy tool
cherrypy.tools.db = SATool()
cherrypy.quickstart(Root(), '', {'/': {'tools.db.on': True,
"request.dispatch": cherrypy.dispatch.MethodDispatcher()}})
以下是应用于sqlalchemy插件receipe的修改
$ diff -up saplugin.py.original saplugin.py
--- saplugin.py.original 2015-06-15 18:14:45.469706863 +0200
+++ saplugin.py 2015-06-15 18:14:37.042741785 +0200
@@ -3,6 +3,7 @@ import cherrypy
from cherrypy.process import wspbus, plugins
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker
+from models import User, Base
__all__ = ['SAEnginePlugin']
@@ -26,7 +27,16 @@ class SAEnginePlugin(plugins.SimplePlugi
self.sa_engine = create_engine('sqlite:///my.db', echo=False)
self.bus.subscribe("bind-session", self.bind)
self.bus.subscribe("commit-session", self.commit)
-
+ # Creating the database
+ self.bus.log('Creating database')
+ self.bus.subscribe("create-all", self.create_all)
+ try:
+ self.create_all()
+ except Exception as err:
+ logging.error("Can't start")
+ logging.error(err.message)
+ sys.exit(1)
+
def stop(self):
self.bus.log('Stopping down DB access')
self.bus.unsubscribe("bind-session", self.bind)
@@ -59,4 +69,8 @@ class SAEnginePlugin(plugins.SimplePlugi
raise
finally:
self.session.remove()
-
+
+ def create_all(self):
+ """ create database structure """
+ self.bus.log('Creating database')
+ Base.metadata.create_all(self.sa_engine)
当我在GET方法的开头转换名称时，这是服务器的日志。
$ python root.py
[15/Jun/2015:18:16:23] ENGINE Listening for SIGHUP.
[15/Jun/2015:18:16:23] ENGINE Listening for SIGTERM.
[15/Jun/2015:18:16:23] ENGINE Listening for SIGUSR1.
[15/Jun/2015:18:16:23] ENGINE Bus STARTING
[15/Jun/2015:18:16:23] ENGINE Starting up DB access
[15/Jun/2015:18:16:23] ENGINE Creating database
[15/Jun/2015:18:16:23] ENGINE Creating database
[15/Jun/2015:18:16:23] ENGINE Started monitor thread 'Autoreloader'.
[15/Jun/2015:18:16:23] ENGINE Started monitor thread '_TimeoutMonitor'.
[15/Jun/2015:18:16:23] ENGINE Serving on 127.0.0.1:8080
[15/Jun/2015:18:16:23] ENGINE Bus STARTED
127.0.0.1 - - [15/Jun/2015:18:16:26] "GET /users/1 HTTP/1.1" 200 14 "" "curl/7.29.0"
127.0.0.1 - - [15/Jun/2015:18:16:28] "GET /users/foo HTTP/1.1" 200 14 "" "curl/7.29.0"
以下是以前日志的查询
$ curl 127.0.0.1:8080/users/1; echo
I'm resource 1
$ curl 127.0.0.1:8080/users/foo; echo
I'm resource 1
以下是数据库的内容
$ sqlite3 my.db
sqlite> .schema
CREATE TABLE users (
id INTEGER NOT NULL,
name VARCHAR,
PRIMARY KEY (id)
);
sqlite> select * from users;
1|foo
2|bar
我不能同时使用装饰器popargs和_cp_dispatch方法。 我还没有找到如何使用装饰器处理我的url段。 当我尝试仅使用_cp_dispatch方法时，我最终得到以下错误：
File "/usr/lib/python2.7/site-packages/cherrypy/_cprequest.py", line 628, in respond
self.get_resource(path_info)
File "/usr/lib/python2.7/site-packages/cherrypy/_cprequest.py", line 744, in get_resource
dispatch(path)
File "/usr/lib/python2.7/site-packages/cherrypy/_cpdispatch.py", line 423, in __call__
resource, vpath = self.find_handler(path_info)
File "/usr/lib/python2.7/site-packages/cherrypy/_cpdispatch.py", line 311, in find_handler
subnode = dispatch(vpath=iternames)
File "root.py", line 49, in _cp_dispatch
vpath[0] = name_to_id(vpath[0], Users)
File "root.py", line 10, in name_to_id
param = cherrypy.request.db.query(table.id).\
File "/usr/lib/python2.7/site-packages/cherrypy/__init__.py", line 208, in __getattr__
return getattr(child, name)
AttributeError: 'Request' object has no attribute 'db'
以下是应用于Users类的修改：
class Users(object):
# [....]
def _cp_dispatch(self, vpath):
if len(vpath) > 1:
raise
vpath[0] = name_to_id(vpath[0], Users)
return vpath
我正在使用以下版本（我正在使用Centos 7环境，并且不能使用来自pip的那些更改）： $ rpm -qa | egrep“cherrypy | sqlalchemy” 蟒蛇-CherryPy的-3.2.2-4.el7.noarch 蟒-SQLAlchemy的-0.9.7-3.el7.x86_64
非常感谢您的帮助!!!!
答案 0 :(得分：0)
documentation中描述了这个问题的解决方案。
我已将以下工具添加到根脚本：
class UserManager(cherrypy.Tool):
def __init__(self):
cherrypy.Tool.__init__(self, 'before_handler',
self.load, priority=10)
def load(self, **kwargs):
req = cherrypy.request
# let's assume we have a db session
# attached to the request somehow
db = req.db
# retrieve the user id and remove it
# from the request parameters
if 'user' in req.params:
user = req.params.pop('user')
if not user.isdigit():
req.params['user'] = db.query(User).\
filter(User.name == user).one()
else:
req.params['user'] = db.query(User).\
filter(User.id == user).one()
cherrypy.tools.user = UserManager()
并重写Users类，如下所示：
@cherrypy.popargs("user")
class Users(object):
exposed = True
@cherrypy.tools.user()
def GET(self, user=None, **kwargs):
if user:
return "I'm resource %s" % user.id
else:
return "All users"
装饰者 @ cherrypy.popargs（＆＃34;用户＆＃34;）告诉我们在网址中抓取第一段并将其存储到密钥＆＃34;用户＆＃34 ;。 装饰器 @ cherrypy.tools.user（）告诉我们在输入 GET 方法之前调用工具用户。 在 UserManager 类的 load 方法中，我将用户的id或名称转换为sqlalchemy模型。