firestore规则中可用的循环？

Question

我想知道是否有更简单的方法来实现这个规则.刚开始尝试使用firestore.

match /emails/{emailId} {

    allow write: if request.resource.data.attachments.size() == 0
    || request.resource.data.attachments.size() == 1 && request.resource.data.attachments[0].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[0].filetype == 'image/png' || request.resource.data.attachments[0].filetype == 'image/jpg' || request.resource.data.attachments[0].filetype == 'application/vnd.ms-excel')
    || request.resource.data.attachments.size() == 2 && request.resource.data.attachments[0].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[0].filetype == 'image/png' || request.resource.data.attachments[0].filetype == 'image/jpg' || request.resource.data.attachments[0].filetype == 'application/vnd.ms-excel') && request.resource.data.attachments[1].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[1].filetype == 'image/png' || request.resource.data.attachments[1].filetype == 'image/jpg' || request.resource.data.attachments[1].filetype == 'application/vnd.ms-excel')
    || request.resource.data.attachments.size() == 3 && request.resource.data.attachments[0].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[0].filetype == 'image/png' || request.resource.data.attachments[0].filetype == 'image/jpg' || request.resource.data.attachments[0].filetype == 'application/vnd.ms-excel') && request.resource.data.attachments[1].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[1].filetype == 'image/png' || request.resource.data.attachments[1].filetype == 'image/jpg' || request.resource.data.attachments[1].filetype == 'application/vnd.ms-excel') && request.resource.data.attachments[2].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[2].filetype == 'image/png' || request.resource.data.attachments[2].filetype == 'image/jpg' || request.resource.data.attachments[2].filetype == 'application/vnd.ms-excel')
    || request.resource.data.attachments.size() == 4 && request.resource.data.attachments[0].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[0].filetype == 'image/png' || request.resource.data.attachments[0].filetype == 'image/jpg' || request.resource.data.attachments[0].filetype == 'application/vnd.ms-excel') && request.resource.data.attachments[1].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[1].filetype == 'image/png' || request.resource.data.attachments[1].filetype == 'image/jpg' || request.resource.data.attachments[1].filetype == 'application/vnd.ms-excel') && request.resource.data.attachments[2].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[2].filetype == 'image/png' || request.resource.data.attachments[2].filetype == 'image/jpg' || request.resource.data.attachments[2].filetype == 'application/vnd.ms-excel') && request.resource.data.attachments[3].fileSize < 3 * 1024 * 1024 && (request.resource.data.attachments[3].filetype == 'image/png' || request.resource.data.attachments[3].filetype == 'image/jpg' || request.resource.data.attachments[3].filetype == 'application/vnd.ms-excel');
}

Answer 1

我们不允许在规则中使用循环结构,因为我们依赖于几种更复杂结构更难的优化技术.我们也不会为规则执行收取计算时间,这意味着我们不希望它们过于复杂且可能具有滥用性.

随着规则的重复,我强烈建议使用function()功能来简化.例如,这是<1/3的大小:

match /emails/{emailId} {
    function attachments (){
      return request.resource.data.attachments();
    }

    function attach_cnt () {
      return attachments().size();
    }

    function valid_size(attach) {
      return attachments()[attach].fileSize < 3 * 1024 * 1024;
    }

    function valid_type(attach) {
      return (attachments()[attach].filetype == 'image/png' 
         || attachments()[attach].filetype == 'image/jpg'
         || attachments()[attach].filetype == 'application/vnd.ms-excel');
    }

    allow write: (attach_cnt() < 1 || (valid_size(0) && valid_type(0)))
    && (attach_cnt() < 2 || (valid_size(1) && valid_type(1)))
    && (attach_cnt() < 3 || (valid_size(2) && valid_type(2)))
    && (attach_cnt() < 4 || (valid_size(3) && valid_type(3)))
}

这是我如何简化它(值得仔细检查,因为我可能错误输入).

1. 我attachments为访问的请求数据创建了一个函数,因为它使用了一个聚合 - 这使得很容易浏览规则.
2. 我做了一个attach_cnt附件数量的功能,因为经过检查了很多.
3. 现在我看到每个附件都有一个文件大小约束,所以我valid_size使用attach我可以传递的参数为该测试创建了一个函数.
4. 接下来是功能valid_type以相同的方式工作,但进行检查以确保它是有效的类型.
5. 现在很明显,对于有2-4个项目的请求,对附件0执行相同的检查等.重新排序某些逻辑使您只能检查每个附件一次.