yet another approach to composable Klein apps

klein_composition_example.py

from twisted.internet import defer
from klein import Klein

from mocked_db import Database


def users_aspect(app: Klein, db: Database):

    @app.route('/')
    @defer.inlineCallbacks
    def users_list(request):
        users = yield db.load_users()
        return ''.join(
            '<a href="{}">{}</a><br/>\n'.format(
                app.url_for(request, user_page.__name__, {'id': user.id}),
                user.name
            )
            for user in users
        )

    @app.route('/<id>', endpoint='user_page')
    @defer.inlineCallbacks
    def user_page(request, id):
        user = yield db.user_by_id(int(id))
        return "<h1>Welcome to {}'s page</h1>\n".format(user.name)


def posts_aspect(app: Klein, db: Database):

    @app.route('/')
    @defer.inlineCallbacks
    def posts_list(request):
        posts = yield db.load_posts()
        return ''.join(
            '<a href="{}">{}</a><br/>\n'.format(
                app.url_for(request, view_post.__name__, {'id': post.id}),
                post.title
            )
            for post in posts
        )

    @app.route('/<id>')
    @defer.inlineCallbacks
    def view_post(request, id):
        post = yield db.post_by_id(int(id))
        signature = '<p>by <a href="{}">{}</a></p>'.format(
            app.url_for(request, 'user_page', {'id': post.user.id}),
            post.user.name
        )
        return '<h1>{}</h1>{}{}'.format(post.title, post.body, signature)


db = Database()
app = Klein()

with app.subroute('/users'):
    users_aspect(app, db)
with app.subroute('/posts'):
    posts_aspect(app, db)

app.run('localhost', 8080)