Get collection of resources.

async def get(self, request):
        """Get collection of resources."""
        form = await self.get_form(request)
        ctx = dict(active=self, form=form, request=request)
        if self.resource:
            return self.app.ps.jinja2.render(self.template_item, **ctx)
        return self.app.ps.jinja2.render(self.template_list, **ctx)