text: from sea.utils import import_string, cached_property
  from sea.local import Proxy
  from sea.middleware import BaseMiddleware
  from sea.pb2 import default_pb2
  from playhouse import db_url
  from peewee import DoesNotExist, DataError
  import grpc
  
  from .validation import ValidationError
  
  
  class Peeweext:
      def __init__(self, ns='PW_'):
          self.ns = ns
  
      def init_app(self, app):
          config = app.config.get_namespace(self.ns)
          self.model_class = import_string(
              config.get('model', 'peeweext.model.Model'))
          conn_params = config.get('conn_params', {})
          self.database = db_url.connect(config['db_url'], **conn_params)
          self._try_setup_celery()
  
      def _get_db(self):
          return self.database
  
      @cached_property
      def Model(self):
          class BaseModel(self.model_class):
              class Meta:
                  database = Proxy(self._get_db)
  
          return BaseModel
  
      def connect_db(self):
          if self.database.is_closed():
              self.database.connect()
  
      def close_db(self):
          if not self.database.is_closed():
              self.database.close()
  
      def _try_setup_celery(self):
          try:
              from celery.signals import task_prerun, task_postrun
              task_prerun.connect(
                  lambda *arg, **kw: self.connect_db(), weak=False)
              task_postrun.connect(
                  lambda *arg, **kw: self.close_db(), weak=False)
          except ImportError:
              pass
  
  
  class PeeweextMiddleware(BaseMiddleware):
      def __init__(self, app, handler, origin_handler):
          super().__init__(app, handler, origin_handler)
          self.pwxs = [
              ext for n, ext in app.extensions.items()
              if isinstance(ext, Peeweext)
          ]
  
      def connect_db(self):
          for pwx in self.pwxs:
              pwx.connect_db()
  
      def close_db(self):
          for pwx in self.pwxs:
              pwx.close_db()
  
      def __call__(self, servicer, request, context):
          try:
              self.connect_db()
              return self.handler(servicer, request, context)
          except DoesNotExist:
              context.set_code(grpc.StatusCode.NOT_FOUND)
              context.set_details('Record Not Found')
          except (ValidationError, DataError) as e:
              context.set_code(grpc.StatusCode.INVALID_ARGUMENT)
              context.set_details(str(e))
          finally:
              self.close_db()
          return default_pb2.Empty()
  