Content negotiation

places.py

from flask import Blueprint
from .helpers import template_or_json
from .views import ServiceView, register_mimetype


places = Blueprint('places', __name__, template_folder='templates')


@places.route('/')
@template_or_json('places/search.html')
def search():
    return {'places': [{'name': 'the place'}]}


class Search(ServiceView):
    @register_mimetype('*/*')
    @register_mimetype('text/html')
    def as_html(self):
        # With 2 mimetypes!
        return "HTML"

    @register_mimetype('application/json')
    def as_json(self):
        return "JSON"

places.add_url_rule('/foo', view_func=Search.as_view('foo'))

views.py

from flask.views import View
from flask import request
from collections import defaultdict


def register_mimetype(mimetype):
    def wrapper(f):
        mimetypes = getattr(f, 'mimetypes', [])
        mimetypes.append(mimetype)
        mimetypes = setattr(f, 'mimetypes', mimetypes)
        return f
    return wrapper


class ServiceView(View):

    def __init__(self, *args, **kwargs):
        self.service_responses = defaultdict(list)
        for attr in dir(self):
            attr = getattr(self, attr)
            mimetypes = getattr(attr, 'mimetypes', [])
            for mt in mimetypes:
                self.service_responses[mt] = attr
        super(ServiceView, self).__init__(*args, **kwargs)

    def dispatch_request(self):
        for mt in request.accept_mimetypes.values():
            if mt in self.service_responses:
                return self.service_responses[mt]()

    @register_mimetype('text/html')
    def as_html(self):
        raise NotImplementedError()

    @register_mimetype('application/json')
    def as_json(self):
        raise NotImplementedError()