Dispatch a request.

async def dispatch(self, request, **kwargs):
        """Dispatch a request."""
        # Authorize request
        self.auth = await self.authorize(request)

        # Load collection
        self.collection = await self.load_many(request)

        # Load resource
        self.resource = await self.load_one(request)

        if request.method == 'GET' and self.resource is None:

            # Filter collection
            self.collection = await self.filter(request)

            # Sort collection
            self.columns_sort = request.query.get('ap-sort', self.columns_sort)
            if self.columns_sort:
                reverse = self.columns_sort.startswith('-')
                self.columns_sort = self.columns_sort.lstrip('+-')
                self.collection = await self.sort(request, reverse=reverse)

            # Paginate collection
            try:
                self.offset = int(request.query.get('ap-offset', 0))
                if self.limit:
                    self.count = await self.count(request)
                    self.collection = await self.paginate(request)
            except ValueError:
                pass

        return await super(AdminHandler, self).dispatch(request, **kwargs)