mapReduce报错

报错：sharded field value must be true

Caused by: com.mongodb.MongoCommandException: Command failed with error 2: ‘sharded field value must be true’ on server 127.0.0.1:27017. The full response is { “ok” : 0.0, “errmsg” : “sharded field value must be true”, “code” : 2, “codeName” : “BadValue” }