mongoTemplate查询数组中元素总数

[公子]

{
  "_class" : "com.kewei.model.Comment",
  "_id" : ObjectId("53a2581fc575bafb12065c36"),
  "commentEmp" : {
    "_id" : "00obbGVRZlJz",
    "name" : "admin"
  },
  "content" : "评论还可以用！？",
  "createDate" : ISODate("2014-06-19T03:25:19.309Z"),
  "dataid" : "014mBN9EXsXe",
  "entityid" : 4,
  "praiseEmp" : [{
      "_id" : "00obbGVRZlJz",
      "name" : "admin"
    }, {
      "_id" : "00oe7O51NsBP",
      "name" : "刘俊杰"
    }],
  "praiseNum" : 2
}

文档结构如上，现想获得数组"praiseEmp"中的元素去重总数，应该如何实现呢？

[soyestrellafortuna]

试试 db.table.distinct('praiseEmp').count() 自己稍微调整一下吧。