1  
   2  #!/usr/bin/env python
   3  # vim:ts=4:sw=4:et
   4  # (c) 2007 Vsevolod Balashov <vsevolod@balashov.name> under terms of LGPL 2.1
   5  # use Storm ORM <https://storm.canonical.com> in WSGI enabled applications
   6  #
   7  # actual version on http://pypi.python.org/pypi/middlestorm
   8  
   9  """WSGI middleware for Storm.
  10  
  11  This is the database access inteface for WSGI enabled (PEP 333) web applications.
  12  
  13  Pylons framework example:
  14  
  15  in wsgiapp.py
  16  
  17  from storm.database import create_database
  18  from middlestorm import MiddleStorm
  19  ...
  20  
  21  # CUSTOM MIDDLEWARE HERE
  22  app = MiddleStorm(app, create_database(config['app_conf']['sqlalchemy.default.uri']))
  23  
  24  in controller:
  25  
  26  class DemoController(BaseController):
  27      def index(self):
  28          store = request.environ['storm.store']
  29          ...
  30  """
  31  
  32  from storm.database import Database
  33  from storm.store import Store
  34  from threading import local
  35  
  36  __all__ = ["MiddleStorm"]
  37  __author__ = "Vsevolod Balashov <http://vsevolod.balashov.name>"
  38  __version__ = "0.1"
  39  
  40  class SingleConn(Database):
  41      """Database proxy class.
  42      Share single database connection between all Store object instances in threads.
  43      If you have readonly database or not use transactions why not?
  44      """
  45      def __init__(self, database):
  46          self._database = database
  47          self._connection = database.connect()
  48      def connect(self):
  49          return self._connection
  50  
  51  class MiddleStorm(object):
  52      """WSGI middleware.
  53      Add Store object instance in environ['storm.store']. Each thread contains own instance.
  54      """
  55  
  56      def __init__(self, app, database, single = False):
  57          """Create WSGI middleware.
  58          @param app: up level application or middleware.
  59          @param database: instance of Database returned create_database.
  60          @param: single: use single database connection in all threads. 
  61          """
  62          assert isinstance(database, Database), \
  63              'database must be subclass of storm.database.Database'
  64          if single:
  65              self._database = SingleConn(database)
  66          else:
  67              self._database = database
  68          self._app = app
  69          self._local = local()
  70  
  71      def __call__(self, environ, start_response):
  72          try:
  73              environ['storm.store']  = self._local.store
  74          except AttributeError:
  75              environ['storm.store']  = \
  76                  self._local.__dict__.setdefault('store', Store(self._database))
  77          return self._app(environ, start_response)