Filter sub documents by sub document in MongoDB?

For this, use aggregate() along with $unwind. Let us create a collection with documents −

> db.demo583.insert([ ...    { ...       "details1" : [ ...          { ...             "details2" : [ ...                { ...                   "isMarried" : true, ...                   "Name" : "Chris" ...                }, ...                { ...                   "isMarried" : true, ...                   "Name" : "Bob" ...                } ...             ] ...          }, ...          { ...             "details2" : [ ...                { ...                   "isMarried" : false, ...                   "Name" : "Chris" ...                }, ...                { ...                   "isMarried" : true, ...                   "Name" : "Mike" ...                } ...             ] ...          } ...       ] ...    } ... ]); BulkWriteResult({    "writeErrors" : [ ],    "writeConcernErrors" : [ ],    "nInserted" : 1,    "nUpserted" : 0,    "nMatched" : 0,    "nModified" : 0,    "nRemoved" : 0,    "upserted" : [ ] })

Display all documents from a collection with the help of find() method −

> db.demo583.find();

This will produce the following output −

{ "_id" : ObjectId("5e91d3c4fd2d90c177b5bcc1"), "details1" : [    { "details2" : [       { "isMarried" : true, "Name" : "Chris" },       { "isMarried" : true, "Name" : "Bob" }    ] },    { "details2" : [       { "isMarried" : false, "Name" : "Chris" },       { "isMarried" : true, "Name" : "Mike" }    ] } ] }

Following is the query to filter sub documents by sub-document −

> var q= [ ...    { ...       "$match": { ...          "details1.details2.isMarried": true, ...          "details1.details2.Name": "Chris" ...       } ...    }, ...    { ...       "$unwind": "$details1" ...    }, ...    { ...       "$unwind": "$details1.details2" ...    }, ...    { ...       "$match": { ...          "details1.details2.isMarried": true, ...          "details1.details2.Name": "Chris" ...       } ...    } ... ]; > db.demo583.aggregate(q).pretty();

This will produce the following output −

{    "_id" : ObjectId("5e91d3c4fd2d90c177b5bcc1"),    "details1" : {       "details2" : {          "isMarried" : true,          "Name" : "Chris"       }    } }