Metadata-Version: 1.1
Name: pyramid_services
Version: 0.4
Summary: A service layer abstraction for the Pyramid Web Framework.
Home-page: https://github.com/mmerickel/pyramid_services
Author: Michael Merickel
Author-email: michael@merickel.org
License: UNKNOWN
Description: ================
        pyramid_services
        ================
        
        .. image:: https://travis-ci.org/mmerickel/pyramid_services.svg?branch=master
           :alt: Travis-CI Build Status
           :target: https://travis-ci.org/mmerickel/pyramid_services
        
        The core of a service layer that integrates with the
        `Pyramid Web Framework <https://docs.pylonsproject.org/projects/pyramid>`__.
        
        ``pyramid_services`` defines a pattern and helper methods for accessing a
        pluggable service layer from within your Pyramid apps.
        
        Installation
        ============
        
        Install from `PyPI <https://pypi.python.org/pyramid_services>`__ using
        ``pip`` or ``easy_install`` inside a virtual environment.
        
        .. code-block:: bash
        
          $ $VENV/bin/pip install pyramid_services
        
        Or install directly from source.
        
        .. code-block:: bash
        
          $ git clone https://github.com/mmerickel/pyramid_services.git
          $ cd pyramid_services
          $ $VENV/bin/pip install -e .
        
        Setup
        =====
        
        Activate ``pyramid_services`` by including it into your pyramid application.
        
        .. code-block:: python
        
          config.include('pyramid_services')
        
        This will add some new directives to your ``Configurator``.
        
        - ``config.register_service(obj, iface=Interface, context=Interface, name='')``
        
          This method will register a service object for the supplied
          ``iface``, ``context``, and ``name``. This effectively registers a
          singleton for your application as the ``obj`` will always be returned when
          looking for a service.
        
        - ``config.register_service_factory(factory, iface=Interface, context=Interface, name='')``
        
          This method will register a factory for the supplied ``iface``,
          ``context``, and ``name``. The factory should be a callable accepting a
          ``context`` and a ``request`` and should return a service object. The
          factory will be used at most once per ``request``/``context``/``name``
          combination.
        
        Usage
        =====
        
        After registering services with the ``Configurator``, they are now
        accessible from the ``request`` object during a request lifecycle via the
        ``request.find_service(iface=Interface, context=_marker, name='')``
        method. Unless a custom ``context`` is passed to ``find_service``, the
        lookup will default to using ``request.context``. The ``context`` will default
        to ``None`` if a service is searched for during or before traversal in Pyramid
        when there may not be a ``request.context``.
        
        .. code-block:: python
        
          svc = request.find_service(ILoginService)
        
        Examples
        ========
        
        Let's create a login service by progressively building up from scratch what
        we want to use in our app.
        
        Basically all of the steps in configuring an interface are optional, but
        they are shown here as best practices.
        
        .. code-block:: python
        
          # myapp/interfaces.py
        
          from zope.interface import Interface
        
          class ILoginService(Interface):
            def create_token_for_login(name):
              pass
        
        With our interface we can now define a conforming instance.
        
        .. code-block:: python
        
          # myapp/services.py
        
          class DummyLoginService(object):
            def create_token_for_login(self, name):
              return 'u:{0}'.format(name)
        
        Let's hook it up to our application.
        
        .. code-block:: python
        
          # myapp/main.py
        
          from pyramid.config import Configurator
        
          from myapp.services import DummyLoginService
        
          def main(global_config, **settings):
            config = Configurator()
            config.include('pyramid_services')
        
            config.register_service(DummyLoginService(), ILoginService)
        
            config.add_route('home', '/')
            config.scan('.views')
            return config.make_wsgi_app()
        
        Finally, let's create our view that utilizes the service.
        
        .. code-block:: python
        
          # myapp/views.py
        
          @view_config(route_name='home', renderer='json')
          def home_view(request):
            name = request.params.get('name', 'bob')
        
            login_svc = request.find_service(ILoginService)
            token = login_svc.create_token_for_login(name)
        
            return {'access_token': token}
        
        If you start up this application, you will find that you can access
        the home url and get custom tokens!
        
        This is cool, but what's even better is swapping in a new service without
        changing our view at all. Let's define a new ``PersistentLoginService``
        that gets tokens from a database. We're going to need to setup some
        database handling, but again nothing changes in the view.
        
        .. code-block:: python
        
          # myapp/services.py
        
          from uuid import uuid4
        
          from myapp.model import AccessToken
        
          class PersistentLoginService(object):
            def __init__(self, dbsession):
              self.dbsession = dbsession
        
            def create_token_for_login(self, name):
              token = AccessToken(key=uuid4(), user=name)
              self.dbsession.add(token)
              return token.key
        
        Below is some boilerplate for configuring a model using the excellent
        `SQLAlchemy ORM <http://docs.sqlalchemy.org>`__.
        
        .. code-block:: python
        
          # myapp/model.py
        
          from sqlalchemy import engine_from_config
          from sqlalchemy.ext.declarative import declarative_base
          from sqlalchemy.orm import sessionmaker
          from sqlalchemy.schema import Column
          from sqlalchemy.types import Text
        
          Base = declarative_base()
        
          def init_model(settings):
            engine = engine_from_config(settings)
            dbmaker = sessionmaker()
            dbmaker.configure(bind=engine)
            return dbmaker
        
          class AccessToken(Base):
            __tablename__ = 'access_token'
        
            key = Column(Text, primary_key=True)
            user = Column(Text, nullable=False)
        
        Now we will update the application to use the new ``PersistentLoginService``.
        However, we may have other services and it'd be silly to create a new
        database connection for each service in a request. So we'll also add a
        service that encapsulates the database connection. Using this technique
        we can wire services together in the service layer.
        
        .. code-block:: python
        
          # myapp/main.py
        
          from pyramid.config import Configurator
          import transaction
          import zope.sqlalchemy
        
          from myapp.model import init_model
          from myapp.services import PersistentLoginService
        
          def main(global_config, **settings):
            config = Configurator()
            config.include('pyramid_services')
            config.include('pyramid_tm')
        
            dbmaker = init_model(settings)
        
            def dbsession_factory(context, request):
              dbsession = dbmaker()
              # register the session with pyramid_tm for managing transactions
              zope.sqlalchemy.register(dbsession, transaction_manager=request.tm)
              return dbsession
        
            config.register_service_factory(dbsession_factory, name='db')
        
            def login_factory(context, request):
              dbsession = request.find_service(name='db')
              svc = PersistentLoginService(dbsession)
              return svc
        
            config.register_service_factory(login_factory, ILoginService)
        
            config.add_route('home', '/')
            config.scan('.views')
            return config.make_wsgi_app()
        
        And finally the home view will remain unchanged.
        
        .. code-block:: python
        
          # myapp/views.py
        
          @view_config(route_name='home', renderer='json')
          def home_view(request):
            name = request.params.get('name', 'bob')
        
            login_svc = request.find_service(ILoginService)
            token = login_svc.create_token_for_login(name)
        
            return {'access_token': token}
        
        Hopefully this pattern is clear. It has several advantages over most basic
        Pyramid tutorials.
        
        - The model is completely abstracted from the views, making both easy to
          test on their own.
        
        - The service layer can be developed independently of the views, allowing
          for dummy implementations for easy creation of templates and frontend
          logic. Later, the real service layer can be swapped in as it's developed,
          building out the backend functionality.
        
        - Most services may be implemented in such a way that they do not depend on
          Pyramid or a particular request object.
        
        - Different services may be returned based on a context, such as the
          result of traversal or some other application-defined discriminator.
        
        Testing Examples
        ================
        
        If you are writing an application that uses ``pyramid_services`` you may want
        to do some integration testing that verifies that your application has
        successfully called ``register_service`` or ``register_service_factory``. Using
        ``Pyramid``'s ``testing`` module to create a ``Configurator`` and after calling
        ``config.include('pyramid_services')`` you may use ``find_service_factory`` to
        get information about a registered service.
        
        Take as an example this test that verifies that ``dbsession_factory`` has been
        correctly registered. This assumes you have a ``myapp.services`` package that
        contains an ``includeme()`` function.
        
        .. code-block:: python
        
          # myapp/tests/test_integration.py
        
          from myapp.services import dbsession_factory, login_factory, ILoginService
        
          class TestIntegration_services(unittest.TestCase):
            def setUp(self):
              self.config = pyramid.testing.setUp()
              self.config.include('pyramid_services')
              self.config.include('myapp.services')
        
            def tearDown(self):
              pyramid.testing.tearDown()
        
            def test_db_maker(self):
              result = self.config.find_service_factory(name='db')
              self.assertEqual(result, dbsession_factory)
        
            def test_login_factory(self):
              result = self.config.find_service_factory(ILoginService)
              self.assertEqual(result, login_factory)
        
        
        0.4 (2016-02-03)
        ================
        
        Backward Incompatibilities
        --------------------------
        
        - Drop Python 3.2 support.
        
        - Use the original service context interface as the cache key instead
          of the current context. This means the service will be properly created
          only once for any context satisfying the original interface.
        
          Previously, if you requested the same service from 2 different contexts
          in the same request you would receive 2 service objects, instead of
          a cached version of the original service, assuming the service was
          registered to satisfy both contexts.
          See https://github.com/mmerickel/pyramid_services/pull/12
        
        0.3 (2015-12-13)
        ================
        
        - When using ``request.find_service`` during or before traversal the
          ``request.context`` is not valid. In these situations the ``context``
          parameter will default to ``None`` instead of raising an exception.
          See https://github.com/mmerickel/pyramid_services/pull/8
        
        - Add ``config.find_service_factory`` and ``request.find_service_factory``.
          See https://github.com/mmerickel/pyramid_services/pull/4
        
        0.2 (2015-03-13)
        ================
        
        - Change ``find_service(..., context=None)`` to use a context of ``None``.
          Previously this would fallback to using ``request.context`` if the
          ``context`` was ``None``. Now ``find_service`` will only fallback to
          ``request.context`` when no ``context`` argument is specified.
          See https://github.com/mmerickel/pyramid_services/pull/3
        
        - Support ``introspectable`` for services so that they show up in the
          pyramid_debugtoolbar and elsewhere.
          See https://github.com/mmerickel/pyramid_services/pull/2
        
        0.1.1 (2015-02-17)
        ==================
        
        - Support for ``request.find_service``, ``config.register_service``, and
          ``config.register_service_factory``.
        - Initial commits.
        
Keywords: pyramid services service layer
Platform: UNKNOWN
Classifier: Development Status :: 4 - Beta
Classifier: Framework :: Pyramid
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 2.6
Classifier: Programming Language :: Python :: 2.7
Classifier: Programming Language :: Python :: 3.3
Classifier: Programming Language :: Python :: 3.4
Classifier: Programming Language :: Python :: 3.5
Classifier: Programming Language :: Python :: Implementation :: CPython
Classifier: Programming Language :: Python :: Implementation :: PyPy
