python - 如何根据其他实体的数据通过tastypie选择在django中创建或不创建实体？

Question

我有一个事件类，其中定义了参与者数量和参与者限制，以及代表事件注册的票证类。

我希望当关联的事件已满时 (maxPersons==registredPersons)，不会创建一个事件的门票。

事件和门票将通过 Android 的 tastypie RESTapi 上传。

请问有什么更简单的方法吗？

所以我有这个类代表一个事件:

class Event(models.Model):
    user = models.ForeignKey(User, unique=False)
    maxPersons = models.IntegerField()
    registredPersons = models.IntegerField()

这个类是事件的注册:

class Ticket(models.Model):
    event = models.ForeignKey(Event, unique=False)
    user = models.ForeignKey(User, unique=False)

这是事件的 tastypie 资源类:

class EventResource(ModelResource):
    user = fields.ForeignKey(UserResource, 'user')
    class Meta:
        queryset = Event.objects.all()
        resource_name = 'events'
        include_resource_uri = False
        authorization= Authorization()
        authentication = BasicAuthentication()



    def alter_list_data_to_serialize(self, request, data_dict):
        if isinstance(data_dict, dict):
            if 'meta' in data_dict:
                #Get rid of the meta object                                                                               
                del(data_dict['meta'])

        return data_dict

这个是票务:

class TicketResource(ModelResource):
    user = fields.ForeignKey(UserResource, 'user')
    event = fields.ForeignKey(EventResource,'journey')
    class Meta:
        queryset = Ticket.objects.all()
        resource_name = 'tickets'
        include_resource_uri = False
        authorization= Authorization()
        authentication = BasicAuthentication()
        filtering = {
            'user': ALL_WITH_RELATIONS,
        }
    def get_object_list(self, request):
        return super(TicketResource, self).get_object_list(request).filter(user = request.user)


    def alter_list_data_to_serialize(self, request, data_dict):
        if isinstance(data_dict, dict):
            if 'meta' in data_dict:
                #Get rid of the meta object                                                                               
                del(data_dict['meta'])


        return data_dict

Answer 1

如果事件已满，仅覆盖授权将不允许用户创建门票。

class TicketAuthorization(Authorization):
    def create_detail(self, object_list, bundle):
        return bundle.obj.event.registredPersons <= bundle.obj.event.maxPersons:

class TicketResource(ModelResource):
    user = fields.ForeignKey(UserResource, 'user')
    event = fields.ForeignKey(EventResource,'journey')
    class Meta:
        queryset = Ticket.objects.all()
        resource_name = 'tickets'
        include_resource_uri = False
        authorization= TicketAuthorization()
        authentication = BasicAuthentication()
        filtering = {
            'user': ALL_WITH_RELATIONS,
        }

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