Source code for ripozo.dispatch_base

Contains the DispatcherBase class
which should be implemented for the
web framework that you are using.
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals

from abc import ABCMeta, abstractmethod, abstractproperty

from ripozo.exceptions import AdapterFormatAlreadyRegisteredException
from ripozo.resources.constructor import ResourceMetaClass
from ripozo.resources.restmixins import AllOptionsResource

import logging
import six
import warnings

_logger = logging.getLogger(__name__)

[docs]class DispatcherBase(object): """ This is an abstract base class that is responsible for handling the interface between a request and the resource as well as the interface between the resource and the response. A new subclass should be developed for every framework that ripozo is supposed to work with. Those extensions should be in separate repositories though. This specific base class is mostly for shortcuts and to give an idea of how to actually implement ripozo with a framework. """ _adapter_formats = None _default_adapter = None
[docs] def __init__(self, auto_options=True, auto_options_name='AutoOptionsResource'): """ :param bool auto_options: Automatically builds out an options endpoint on the base url that points to all other resources. :param unicode auto_options_name: The name of the auto options resource class. Available in cases of multiple dispatchers. """ self.auto_options = auto_options if self.auto_options: cls = ResourceMetaClass(str(auto_options_name), (AllOptionsResource,), dict(linked_resource_classes=[])) self.auto_options_class = cls self.register_resources(self.auto_options_class)
@property def adapter_formats(self): """ Returns the mutable _adapter_formats. If the _adapter_formats property is None then it first sets cls._adapter_formats to an empty dictionary. :rtype: dict """ if self._adapter_formats is None: self._adapter_formats = {} return self._adapter_formats @abstractproperty def base_url(self): """ :return: The base url including the domain and protocol This needs to be included so that the adapters can construct fully qualified urls. However, they have no way of directly identifying that so they need to be able to get it from the dispatcher. :rtype: unicode """ pass @property def default_adapter(self): """ :return: The AdapterBase subclass that is the default adapter to use when the client doesn't explicitly request a specific adapter. If no default adapter is set when register_adapters is called, then the first adapter provided to register_adapters will be set as the default adapter. :rtype: AdapterBase """ return self._default_adapter @default_adapter.setter def default_adapter(self, adapter_class): """ Sets the default adapter to use when the client does not explicitly ask for a certain adapter type. :param type adapter_class: the class to use as the default adapter class """'Setting the default adapter for a Dispatcher as %s', adapter_class) self._default_adapter = adapter_class
[docs] def register_adapters(self, *adapter_classes): """ Registers a list of valid adapter classes with this dispatcher. It will take the formats attribute from the AdapterBase subclass and use each of those as a key with the value pointing. If _default_adapter is not set, then the first adapter_class will be the default adapter to use when returning responses. :param list adapter_classes: A list of subclasses of AdapterBase that specify what formats are available for this dispatcher :raises: AdapterFormatAlreadyRegisteredException """ if len(adapter_classes) > 0 and self.default_adapter is None: self.default_adapter = adapter_classes[0] for klass in adapter_classes: for format_name in klass.formats: if format_name in self.adapter_formats or format_name is None: msg = ('The format {0} has already been registered' ' for the class {1}. The class {2} was attempting' ' to override it.'.format(format_name, self.adapter_formats[format_name].__name__, klass.__name__)) raise AdapterFormatAlreadyRegisteredException(msg) _logger.debug('Registering format %s to be hanlded by the AdapterBase' ' subclass %s', format_name, klass) self.adapter_formats[format_name] = klass
[docs] def register_resources(self, *classes): """ A shortcut for register multiple classes at once. :param list classes: A list of ResourceBase subclasses that are being registered with this dispatcher. """ for klass in classes: self._register_class_routes(klass)
def _register_class_routes(self, klass): """ Register a subclass of the ResourceBase on the framework implementation. This is so that the actual actions on the resources can be dispatched to by the framework. :param ripozo.viewsets.resource_base.ResourceBase klass: The class whose endpoints must be registered """ if self.auto_options \ and klass not in self.auto_options_class.linked_resource_classes\ and klass is not self.auto_options_class: self.auto_options_class.linked_resource_classes.append(klass) self._check_relationships(klass) for endpoint, routes in six.iteritems(klass.endpoint_dictionary()): endpoint = '{0}__{1}'.format(klass.__name__, endpoint) for options in routes: options = options.copy() route = options.pop('route', klass.base_url) methods = options.pop('methods', ['GET'])'Registering the endpoint %s to handle route %s' ' with the methods %s on a DispatcherBase ' 'subclass', endpoint, route, methods) self.register_route(endpoint, route=route, methods=methods, **options) self._check_relationships(klass) @abstractmethod
[docs] def register_route(self, endpoint, endpoint_func=None, route=None, methods=None, **options): """ Registers an individual route on the framework. This method gives a specific framework the opportunity to actually dispatch the incoming requests appropriately. :param unicode endpoint: The name of the endpoint :param method endpoint_func: The endpoint_func that is responsible for actually performing the actions requested :param unicode route: The route template for this endpoint :param list methods: A list of the methods on this route that will point to the endpoint_funct :param dict options: A dictionary of additional options. """ pass
[docs] def dispatch(self, endpoint_func, accepted_mimetypes, request, *args, **kwargs): """ A helper to dispatch the endpoint_func, get the ResourceBase subclass instance, get the appropriate AdapterBase subclass and return an instance created with the ResourceBase. :param method endpoint_func: The endpoint_func is responsible for actually get the ResourceBase response :param list accepted_mimetypes: The mime types accepted by the client. If none of the mimetypes provided are available the default adapter will be used. :param RequestContainer request: The request object :param list args: a list of args that wll be passed to the endpoint_func :param dict kwargs: a dictionary of keyword args to pass to the endpoint_func :return: an instance of an AdapterBase subclass that can be used to find :rtype: """'Dispatching request to endpoint function: %s with args:' ' %s and kwargs:%s', endpoint_func, args, kwargs) adapter_class = self.get_adapter_for_type(accepted_mimetypes) request = adapter_class.format_request(request) result = endpoint_func(request, *args, **kwargs)'Using adapter %s to format response for format' ' type %s', adapter_class, accepted_mimetypes) adapter = adapter_class(result, base_url=self.base_url) return adapter
[docs] def get_adapter_for_type(self, accept_mimetypes): """ Gets the appropriate adapter class for the specified format type. For example, if the format_type was siren it would return the SirenAdapter. Returns the default adapter If it cannot not find an adapter for the format_type. :param list accept_mimetypes: A list of the mime types accepted by the client. :return: A BaseAdapter subclass for the best matched accept type. :rtype: type """ for mimetype in accept_mimetypes: if mimetype in self.adapter_formats: return self.adapter_formats.get(mimetype) return self.default_adapter
@staticmethod def _check_relationships(klass): """ Checks that all relationships are valid in that their relation string is a real class. Raises a warngin if the relation is not valid. :param type klass: The klass to check """ for rel in klass.relationships: if rel._relation not in ResourceMetaClass.registered_names_map: warnings.warn('The relation property {0} on the ' 'relationship {1} for the class ' '{2} has not been registered.' ''.format(rel._relation,, klass.__name__)) for rel in klass.links: if rel._relation not in ResourceMetaClass.registered_names_map: warnings.warn('The relation property {0} on the ' 'link {1} for the class ' '{2} has not been registered.' ''.format(rel._relation,, klass.__name__))