CODEWITHSUNDEEP
mongodbmapreduceaggregation-frameworkaggregation
kisor
kisor

Reputation: 484

aggregation and MapReduce in mongodb

I have collections of error logs with the type of error and date of the error log, as error_type and error_date.what I need to perform is group error logs from type in the particular month, I used the $group as aggregation pipeline to group either in month or from error type. what is wish to get data are like this

[{
  _id: 10, ///month wise group
  logs: {
    error_type1: ["error logs array of type 1"],
    error_type2: ["error logs array of type 2"]
  }
},
{
  _id: 11, ///month wise group
  logs: {
    error_type1: ["error logs array of type 1"],
    error_type2: ["error logs array of type 2"]
  }
}]

and my aggregation code currently is 

 rfidAttErrorSchema.aggregate([{
      $match: condition
    }, {
      $group: {
        _id: {
          $month: "$error_date"
        },
        logs: {
          $push: "$$ROOT"
        }
      }
    }, {
      $sort: {
        'error_date': -1
      }
    }
  ],
  function (err, data) {
    if (err) {
      return res.status(500).json({
        result: err
      });
    }
    console.log("data is  now  data", data);
    res.json({
      result: data
    });
});

can someone help me to get this using $group aggregation pipeline twice or using MapReduce of MongoDB? any suggestions and help are highly appreciated

Upvotes: 0

Views: 61

Answers (1)

s7vr
s7vr

Reputation: 75934

You can replace $group with 

{ $group: { _id: { month:{$month: "$error_date"}, error_type:"$error_type", }, data: { $push: "$$ROOT" } } }, 
{ $group: { _id: "$_id.month", logs: { $push: {error_type:"$_id.error_type",data:"$data" } } } }

For expected format you can use 3.4.4 $arrayToObject to convert the keys into named keys.Something like 

{ $group: { _id: { month:{$month: "$error_date"}, error_type:"$error_type", }, data: { $push: "$$ROOT" } } }, 
{ $group: { _id: "$_id.month", logs: { $push: {k:"$_id.error_type",v:"$data" } } } }, 
{ $addFields:{logs:{"$arrayToObject":"$logs"}}}

Adjust the $sort to include the month {$sort: {'_id': -1}}

Upvotes: 1

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