mongodb ReferenceError: map is not defined

错误

ReferenceError: map is not defined

操作

> map
2017-02-23T14:52:43.197+0800 ReferenceError: map is not defined
> reduce
2017-02-23T14:52:52.121+0800 ReferenceError: reduce is not defined

> db.user.mapReduce(map,reduce,{"out":"collection"})
2017-02-23T14:54:13.693+0800 ReferenceError: map is not defined

解释：

map跟reduce未定义

解决

1、先查看集合

> db.user.find()
{ "_id" : ObjectId("58ae37681263f741cb833fc2"), "name" : "keilson", "age" : 30,
"gender" : "M" }
{ "_id" : ObjectId("58ae39a11263f741cb833fc3"), "name" : "Tom", "age" : 20, "gen
der" : "M" }
{ "_id" : ObjectId("58ae81c38f72bc301b434c6a"), "name" : "lili", "age" : 25, "ge
nder" : "F" }
{ "_id" : ObjectId("58ae82118f72bc301b434c6b"), "name" : "lili", "age" : 25, "ge
nder" : "F" }

2、定义map跟reduce 

 var map= function(){emit(this.name,this.age);}

 var reduce = function(key,values){return Array.sum(values)}



 db.user.mapReduce(map,reduce,{"out":"collection"})


       "result" : "collection",
       "timeMillis" : 53,
       "counts" : {
               "input" : 4,
               "emit" : 4,
               "reduce" : 1,
               "output" : 3
       },
       "ok" : 1

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