基于订单号在mongoDB中排序

Question

我在这份文件中收集了一份“A”：

 {
   "InsuranceCompany" : {
      "fieldlabel" : "InsuranceCompany",
      "fieldname" : "InsuranceCompany",
      "fieldtype" : "dropdown",
      "required" : "1",
      "default_value" : "",
      "placeholder" : "InsuranceCompany",
      "order_no" : "3",
      "formgroup" : "policyDetails",
      "can_delete" : "1",
      "status" : "1"
   },
   "PolicyNumber" : {
      "fieldlabel" : "PolicyNumber",
      "fieldname" : "PolicyNumber",
      "fieldtype" : "text",
      "required" : "1",
      "default_value" : "",
      "placeholder" : "Policy Number",
      "order_no" : "1",
      "formgroup" : "policyDetails",
      "can_delete" : "1",
      "status" : "1"
   },
   "NoOfYear" : {
      "fieldlabel" : "NoOfYear",
      "fieldname" : "NoOfYear",
      "fieldtype" : "text",
      "required" : "1",
      "default_value" : "",
      "placeholder" : "No Of Year",
      "order_no" : "2",
      "formgroup" : "policyDetails",
      "can_delete" : "1",
      "status" : "1"
   }
}

我想根据order_no对它进行排序，结果应该是：

{
  "PolicyNumber" : {
      "fieldlabel" : "PolicyNumber",
      "fieldname" : "PolicyNumber",
      "fieldtype" : "text",
      "required" : "1",
      "default_value" : "",
      "placeholder" : "Policy Number",
      "order_no" : "1",
      "formgroup" : "policyDetails",
      "can_delete" : "1",
      "status" : "1"
   },
   "NoOfYear" : {
      "fieldlabel" : "NoOfYear",
      "fieldname" : "NoOfYear",
      "fieldtype" : "text",
      "required" : "1",
      "default_value" : "",
      "placeholder" : "No Of Year",
      "order_no" : "2",
      "formgroup" : "policyDetails",
      "can_delete" : "1",
      "status" : "1"
   },
   "InsuranceCompany" : {
      "fieldlabel" : "InsuranceCompany",
      "fieldname" : "InsuranceCompany",
      "fieldtype" : "dropdown",
      "required" : "1",
      "default_value" : "",
      "placeholder" : "InsuranceCompany",
      "order_no" : "3",
      "formgroup" : "policyDetails",
      "can_delete" : "1",
      "status" : "1"
   }
}

我试过这个问题：

db.A.aggregate([
{ $sort : { order_no : -1 } }
]).pretty()

但它对我不起作用，因为它返回相同的序列。