api.py

import functools
import flask
import inspect
import sys
import traceback


def infer_args(func):
    argspec = inspect.getargspec(func)
    if argspec.defaults is None:
        defaults = {}
    else:
        defaults = dict((d for d in zip(reversed(argspec.args), argspec.defaults)))

    return dict((a, str) for a in argspec.args), defaults


class Api(object):

    def __init__(self, name, mod_name, prefix=None, description=None, **kwargs):
        if prefix is None:
            prefix = "/%s" % name
        self.description = description
        self.name = name
        self.url_prefix = prefix
        self.app = flask.Blueprint(name, mod_name, url_prefix=prefix, **kwargs)
        self.endpoints = {}

    def endpoint(self, endpoint_name, types=None, data_key="data", defaults=None):
        def annotate(func):
            args, actual_defaults = infer_args(func)
            if types is not None:
                args.update(types)
            if defaults is not None:
                actual_defaults = defaults
                
            @functools.wraps(func)
            def endpoint():
                try:
                    view_args = actual_defaults.copy()
                    for key, value in flask.request.values.iteritems():
                        view_args[key] = args[key](value)
                    return flask.jsonify({"success": True, data_key: func(**view_args)})
                except Exception, e:
                    rv = {"success": False}
                    if isinstance(e, (KeyError, )):
                        rv["message"] = "Item not Found: %s" % e.message
                    else:
                        rv["message"] = str(e.message or "Unknown Error")
                    print >>sys.stderr, traceback.format_exc()
                    rv["traceback"] = traceback.format_exc()
                    response = flask.jsonify(rv)
                    response.status_code = getattr(e, "code", 500)
                    flask.request.log("ERROR", "error", "Error with %s: '%r'",
                                      flask.request.path, e)
                    return response
            self.endpoints[endpoint_name] = (args, data_key, actual_defaults, func.__doc__ or "")
            self.app.route("/%s" % endpoint_name, methods=("GET", "POST"))(endpoint)
            return func
        return annotate

usage.py

import path.to.api
api = path.to.api.Api("usage", __name__, description="Example")


@api.endpoint("add")
def add_numbers(a, b, c=0):
    return a+b+c

# wget http://server:5000/usage/add?a=1&b=2
# wget http://server:5000/usage/add?a=1&b=2&c=3
#
# OR
#
# import usage
# usage.add_numbers(1, 2)