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from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
from flask import request, Response
from functools import wraps
from ripozo.dispatch_base import DispatcherBase
from ripozo.exceptions import RestException
from ripozo.utilities import join_url_parts
from ripozo.resources.request import RequestContainer
from werkzeug.routing import Map
import logging
import six
_logger = logging.getLogger(__name__)
class _CaseInsentiveDict(dict):
def __setitem__(self, key, value):
super(_CaseInsentiveDict, self).__setitem__(key.lower(), value)
def __getitem__(self, key):
return super(_CaseInsentiveDict, self).__getitem__(key.lower())
def exception_handler(dispatcher, accepted_mimetypes, exc):
Responsible for handling exceptions in the project.
This catches any RestException (from ripozo.exceptions)
and calls the format_exception class method on the adapter
class. It will appropriately set the status_code, response,
and content type for the exception.
:param FlaskDispatcher dispatcher: A FlaskDispatcher instance
used to format the exception
:param list accepted_mimetypes: A list of the accepted mimetypes
for the client.
:param Exception exc: The exception that was raised.
:return: A flask Response object.
:rtype: flask.Response
if isinstance(exc, RestException):
adapter_klass = dispatcher.get_adapter_for_type(accepted_mimetypes)
response, content_type, status_code = adapter_klass.format_exception(exc)
return Response(response=response, content_type=content_type, status=status_code)
raise exc
def get_request_query_body_args(request_obj):
Gets the request query args and the
body arguments. It gets the query_args from
the flask request.args and transforms it from an
ImmutableMultiDict to a dict. It attempts to retrieve
json for the body first. If it doesn't find any it
looks at the form otherwise it returns an empty dictionary.
The body is also transformed from an ImmutableMultiDict to
a builtin dict.
:param flask.Request request_obj: A Flask request object.
:return: A tuple of the appropriately formatted query
args, body args, and headers
:rtype: (dict, dict, dict)
query_args = dict(request_obj.args)
body = dict(
request_obj.get_json(force=True, silent=True) or
request_obj.form or
# Make a copy of the headers
headers = _CaseInsentiveDict()
for key, value in six.iteritems(request_obj.headers):
headers[key] = value
return query_args, body, headers
class FlaskDispatcher(DispatcherBase):
This is the actual dispatcher responsible for integrating
ripozo with flask. Pretty simple right?
def __init__(self, app, url_prefix='', error_handler=exception_handler,
argument_getter=get_request_query_body_args, **kwargs):
Initialize the adapter. The app can actually be either a flask.Flask
instance or a flask.Blueprint instance.
:param flask.Flask|flask.Blueprint app: The flask app that is responsible for
handling the web application.
:param unicode url_prefix: The url prefix will be prepended to
every route that is registered on this dispatcher. It is
helpful if, for example, you want to expose your api
on the '/api' path.
:param function error_handler: A function that takes a dispatcher,
accepted_mimetypes, and exception that handles error responses.
It should return a flask.Response instance.
:param function argument_getter: The function responsible for
getting the query/body arguments from the Flask Request as a
tuple. This function should return (dict, dict,) with the first
as the query args and the second as the request body args.
""" = app
self.url_map = Map()
self.function_for_endpoint = {}
if url_prefix and not url_prefix.startswith('/'):
url_prefix = '/{0}'.format(url_prefix)
self.url_prefix = url_prefix
self.error_handler = error_handler
self.argument_getter = argument_getter
super(FlaskDispatcher, self).__init__(**kwargs)
def base_url(self):
:return: The base_url for this adapter. It simply joins
the provided base_url in the __init__ method and
joins it with the ``request.url_root``. If this
app provided is actually a blueprint, it will
return join the blueprints url_prefix in between
:rtype: unicode
if getattr(, 'url_prefix', None):
return join_url_parts(request.url_root,, self.url_prefix)
return join_url_parts(request.url_root, self.url_prefix)
def register_route(self, endpoint, endpoint_func=None, route=None, methods=None, **options):
Registers the endpoints on the flask application
or blueprint. It does so by using the add_url_rule on
the blueprint/app. It wraps the endpoint_func with the
``flask_dispatch_wrapper`` which returns an updated function.
This function appropriately sets the RequestContainer object
before passing it to the apimethod.
:param unicode endpoint: The name of the endpoint. This is typically
used in flask for reversing urls
:param method endpoint_func: The actual function that is going to be called.
This is generally going to be a @apimethod decorated, ResourceBase subclass
:param unicode route: The actual route that is going to be used.
:param list methods: The http verbs that can be used with this endpoint
:param dict options: The additional options to pass to the add_url_rule
valid_flask_options = ('defaults', 'subdomain', 'methods', 'build_only',
'endpoint', 'strict_slashes', 'redirect_to',
'alias', 'host')
route = join_url_parts(self.url_prefix, route)
# Remove invalid flask options.
options_copy = options.copy()
for key, value in six.iteritems(options_copy):
if key not in valid_flask_options:
options.pop(key, None), endpoint=endpoint,
view_func=flask_dispatch_wrapper(self, endpoint_func, self.argument_getter),
methods=methods, **options)
def flask_dispatch_wrapper(dispatcher, f, argument_getter=get_request_query_body_args):
A decorator for wrapping the apimethods provided to the
dispatcher. The actual wrapper performs that actual
construction of the RequestContainer, determines the appropriate
adapter to use, dispatches the method, and passes errors to
the dispatcher.error_handler method. Finally, it will return
a flask.Response instance except in the case of an exception
raised by the dispatch.error_handler (typically error_handlers
only handle certain sets of exceptions).
:param FlaskDispatcher dispatcher: The dispatcher that is
created this.
:param function f: The apimethod to wrap.
:param function argument_getter: The function that takes a flask
Request object and uses it to get the query arguments and the
body arguments as a tuple.
def flask_dispatch(**urlparams):
This is the method that dispatches the requests to endpoints
that are part of the classes registered with this dispatcher instance.
For example if a class Foo that has apimethods bar and baz in it and
that class is registered on an instance of this dispatcher, then when a
request that matches the route for bar or baz is caught by the flask app
it is first directed here. Here it is further directs it to the appropriate
method (bar or baz) and an appropriate response is returned.
This effectively translates Flask's interpretation of requests and responses
into ripozo's interpretation of them.
:param dict urlparams: The url params that were passed by the flask
app. Typically these are going to be the _pks for the specified
:return: A response that the flask application can return.
:rtype: flask.Response
request_args, body_args, headers = argument_getter(request)
ripozo_request = RequestContainer(url_params=urlparams,
accepted_mimetypes = [accept[0] for accept in request.accept_mimetypes]
adapter = dispatcher.dispatch(f, accepted_mimetypes, ripozo_request)
except Exception as e:
return dispatcher.error_handler(dispatcher, accepted_mimetypes, e)
return Response(response=adapter.formatted_body, headers=adapter.extra_headers,
content_type=adapter.extra_headers['Content-Type'], status=adapter.status_code)
return flask_dispatch