Question

我正在尝试按照某个日期对所有用户进行分组，我想要的是月份名称和用户数量，月份将是一个变量，因此可以更改为年份或星期。这是我的代码：

logs = user_collection.aggregate([
        # Lets find our records
        {"$match" => {"zip_code" => {"$exists" => true}, "dob" => {"$exists" => true}, "firstname" => {"$exists" => true}, "lastname" => {"$exists" => true}, "email" => {"$exists" => true}}}, 

        # Now lets group on the name counting how many grouped documents we have
        {"$group" => {"date" => { "$#{period_type}" => "$created" }, "count" => {"$sum" => "1" }}} 
      ])

在我的情况下，

period_type是月份。好像我做错了，因为我有这个错误

Mongo::OperationFailure: Database command 'aggregate' failed: (errmsg: 'exception: unknown group operator '$month''; code: '15952'; ok: '0.0').

Answer 1

这里有几个问题。首先，$group运算符组按照您指定的_id进行分组，此处缺少。其次，所有字段（_id除外）都需要遵循<field1>: { <accumulator1> : <expression1> } structure。

尝试用您的组行代替：

{"$group" => {"_id" => { "$#{period_type}" => "$created" }, "count" => {"$sum" => "1" }}}

mongodb聚合用户按日期计算

1 个答案: