How To Get Data Mongo Data Using Aggregate Mongodb

Suppose we have 10 collection, then we have to find the count on the basis of tag_id. For example, if tag_id contains 0 and 1, then we have to count all the data, as well as counti

Solution 1:

You can use below aggregation pipeline.

The below query will $unwind the tag_id followed by $group to count email and $cond operator to count the unread email.

db.collection.aggregate(
 {$unwind:{path:"$tag_id", preserveNullAndEmptyArrays:true}}, 
 {$group:{
    _id:"$tag_id", 
     count_email:{$sum:1},
     unread:{$sum:{$cond:[{$eq:["$unread", "false"]}, 0, 1]}}
    }
  }
);