Synnefo

#

# Copyright 2011 GRNET S.A. All rights reserved.

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# without modification, are permitted provided that the following

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#      disclaimer.

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#      disclaimer in the documentation and/or other materials

#      provided with the distribution.

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# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

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from django import http

from django.template import RequestContext, loader

from django.utils import simplejson as json

from django.core import serializers

from django.core.urlresolvers import reverse

from django.http import HttpResponse

from django.core.exceptions import ValidationError, NON_FIELD_ERRORS

from synnefo.lib.astakos import get_user

from django.conf import settings

# base view class

# https://github.com/bfirsh/django-class-based-views/blob/master/class_based_views/base.py

class View(object):

    """

    Intentionally simple parent class for all views. Only implements

    dispatch-by-method and simple sanity checking.

    """

    method_names = ['GET', 'POST', 'DELETE', 'HEAD', 'OPTIONS', 'TRACE']

    def __init__(self, *args, **kwargs):

        """

        Constructor. Called in the URLconf; can contain helpful extra

        keyword arguments, and other things.

        """

        # Go through keyword arguments, and either save their values to our

        # instance, or raise an error.

        for key, value in kwargs.items():

            if key in self.method_names:

                raise TypeError(u"You tried to pass in the %s method name as a"

                                u" keyword argument to %s(). Don't do that."

                                % (key, self.__class__.__name__))

            if hasattr(self, key):

                setattr(self, key, value)

            else:

                raise TypeError(u"%s() received an invalid keyword %r" % (

                    self.__class__.__name__,

                    key,

                ))

    @classmethod

    def as_view(cls, *initargs, **initkwargs):

        """

        Main entry point for a request-response process.

        """

        def view(request, *args, **kwargs):

            user = get_user(request, settings.ASTAKOS_URL)

            if not request.user_uniq:

                return HttpResponse(status=401)

            self = cls(*initargs, **initkwargs)

            return self.dispatch(request, *args, **kwargs)

        return view

    def dispatch(self, request, *args, **kwargs):

        # Try to dispatch to the right method for that; if it doesn't exist,

        # raise a big error.

        if hasattr(self, request.method.upper()):

            self.request = request

            self.args = args

            self.kwargs = kwargs

            data = request.raw_post_data

            if request.method.upper() in ['POST', 'PUT']:

                # Expect json data

                if request.META.get('CONTENT_TYPE').startswith('application/json'):

                    try:

                        data = json.loads(data)

                    except ValueError:

                        return http.HttpResponseServerError('Invalid JSON data.')

                else:

                    return http.HttpResponseServerError('Unsupported Content-Type.')

            try:

                return getattr(self, request.method.upper())(request, data, *args, **kwargs)

            except ValidationError, e:

                # specific response for validation errors

                return http.HttpResponseServerError(json.dumps({'errors':

                    e.message_dict, 'non_field_key':

                    NON_FIELD_ERRORS }))

        else:

            allowed_methods = [m for m in self.method_names if hasattr(self, m)]

            return http.HttpResponseNotAllowed(allowed_methods)

class JSONRestView(View):

    """

    Class that provides helpers to produce a json response

    """

    url_name = None

    def __init__(self, url_name, *args, **kwargs):

        self.url_name = url_name

        return super(JSONRestView, self).__init__(*args, **kwargs)

    def update_instance(self, i, data, exclude_fields=[]):

        update_keys = data.keys()

        for field in i._meta.get_all_field_names():

            if field in update_keys and (field not in exclude_fields):

                i.__setattr__(field, data[field])

        return i

    def instance_to_dict(self, i, exclude_fields=[]):

        """

        Convert model instance to python dict

        """

        d = {}

        d['uri'] = reverse(self.url_name, kwargs={'id': i.pk})

        for field in i._meta.get_all_field_names():

            if field in exclude_fields:

                continue

            d[field] = i.__getattribute__(field)

        return d

    def qs_to_dict_iter(self, qs, exclude_fields=[]):

        """

        Convert queryset to an iterator of model instances dicts

        """

        for i in qs:

            yield self.instance_to_dict(i, exclude_fields)

    def json_response(self, data):

        return http.HttpResponse(json.dumps(data), mimetype="application/json")

class ResourceView(JSONRestView):

    method_names = ['GET', 'POST', 'PUT', 'DELETE']

    model = None

    exclude_fields = []

    def queryset(self):

        return self.model.objects.all()

    def instance(self):

        """

        Retrieve selected instance based on url parameter

        id parameter should be set in urlpatterns expression

        """

        try:

            return self.queryset().get(pk=self.kwargs.get("id"))

        except self.model.DoesNotExist:

            raise http.Http404

    def GET(self, request, data, *args, **kwargs):

        return self.json_response(self.instance_to_dict(self.instance(),

            self.exclude_fields))

    def PUT(self, request, data, *args, **kwargs):

        instance = self.instance()

        self.update_instance(instance, data, self.exclude_fields)

        instance.full_clean()

        instance.save()

        return self.GET(request, data, *args, **kwargs)

    def DELETE(self, request, data, *args, **kwargs):

        self.instance().delete()

        return self.json_response("")

class CollectionView(JSONRestView):

    method_names = ['GET', 'POST']

    model = None

    exclude_fields = []

    def queryset(self):

        return self.model.objects.all()

    def GET(self, request, data, *args, **kwargs):

        return self.json_response(list(self.qs_to_dict_iter(self.queryset(),

            self.exclude_fields)))

    def POST(self, request, data, *args, **kwargs):

        instance = self.model()

        self.update_instance(instance, data, self.exclude_fields)

        instance.full_clean()

        instance.save()

        return self.json_response(self.instance_to_dict(instance,

            self.exclude_fields))

class UserResourceView(ResourceView):

    """

    Filter resource queryset for request user entries

    """

    def queryset(self):

        return super(UserResourceView,

                self).queryset().filter(user=self.request.user_uniq)

class UserCollectionView(CollectionView):

    """

    Filter collection queryset for request user entries

    """

    def queryset(self):

        return super(UserCollectionView, self).queryset().filter(user=self.request.user_uniq)

    def POST(self, request, data, *args, **kwargs):

        instance = self.model()

        self.update_instance(instance, data, self.exclude_fields)

        instance.user = request.user_uniq

        instance.full_clean()

        instance.save()

        return self.json_response(self.instance_to_dict(instance,

            self.exclude_fields))