MongoDB学习笔记(聚合)(二)
: {count: 0},
... reduce: function(obj,prev){ prev.count++;},
... finalize: function(out){ out.scaledCount = out.count * 10 } --在结果文档中新增一个键。
... } )
[
{
"day" : "2012-08-20",
"count" : 2,
"scaledCount" : 20
}, www.2cto.com
{
"day" : "2012-08-21",
"count" : 2,
"scaledCount" : 20
},
{
"day" : "2012-08-22",
"count" : 1,
"scaledCount" : 10
}
]