[PYTHON] Insert processing before and after the view function in Pyramid's own View Decorator

[2015/3/20 Updated to the contents found by various investigations. Something different]

With user authentication & Authenticated page, the user name is displayed in the header part on any screen, and the standard processing when creating a common Web application is automated.

--Define a view_decorator that allows the view to run only if you are authenticated and have the permission user --Similarly, allow view to be executed only with the permission of admin --Access the User object by accessing request.user --Run SQL and search for models.User only the first time you access it

def permission_view_config(permission):
    def pvc(**params):
        settings = dict(permission=permission, _depth=1)
        settings.update(params)

        def wrapped_view_config(original_func):
            return view_config(**settings)(original_func)
        return wrapped_view_config
    return pvc


user_view_config = permission_view_config('user')
admin_view_config = permission_view_config('admin')

__init__.py

def groupfinder(user_code, request):
    if not request.user:
        return []
    elif request.user.is_admin:
        return ['group:users', 'group:admin']
    else:
        return ['group:users']


def get_user(request):
    user_id = unauthenticated_userid(request)
    if user_id is not None:
        return DBSession.query(User).get(user_id)


class RootFactory(object):
    __acl__ = [
        (Allow, 'group:users', 'user'),
        (Allow, 'group:admin', 'admin')
    ]

    def __init__(self, request):
        pass


def main(global_config, **settings):
    # ...
    config = Configurator(settings=settings, root_factory='.RootFactory')

    #Get when you access the user property of request_Specify that you should be a user. This is important.
    config.set_request_property(get_user, 'user', reify=True)

    authn_policy = AuthTktAuthenticationPolicy('...', callback=groupfinder, hashalg='sha512')
    authz_policy = ACLAuthorizationPolicy()
    config.set_authentication_policy(authn_policy)
    config.set_authorization_policy(authz_policy)
    # ...

If you use it like this

views.py

@user_view_config(route_name='index', renderer='templates/index.jinja2')
def index(request):
    #This is only for people who have user permission
    do_something_with(request.user)  #user can be used
    return {'name': 'my_app'}

@admin_view_config(route_name='index', renderer='templates/add_user.jinja2')
def add_user(request):
    #This is only for those who have admin permission
    do_something_with(request.user)  #user can be used
    return {'name': 'my_app'}

inspired by Implement a custom View Decorator in Pyramid