Querying an array of arrays in MongoDB?

Use $in operator to query an array of arrays in MongoDB. To understand the concept, let us create a collection with the document. The query to create a collection with a document is as follows −

> db.arrayOfArraysDemo.insertOne({"EmployeeName":"Larry","EmployeeSkills":[["Java","MongoDB","MySQL","SQL Server"]]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c7f7a8d8d10a061296a3c5b") } > db.arrayOfArraysDemo.insertOne({"EmployeeName":"Mike","EmployeeSkills":[["C","C++"]]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c7f7aa68d10a061296a3c5c") }

Display all documents from a collection with the help of find() method. The query is as follows −

> db.arrayOfArraysDemo.find().pretty();

The following is the output −

{    "_id" : ObjectId("5c7f7a8d8d10a061296a3c5b"),    "EmployeeName" : "Larry",    "EmployeeSkills" : [       [          "Java",          "MongoDB",          "MySQL",          "SQL Server"       ]    ] } {    "_id" : ObjectId("5c7f7aa68d10a061296a3c5c"),    "EmployeeName" : "Mike",    "EmployeeSkills" : [       [          "C",          "C++"       ]    ] }

Here is the query for querying an array of arrays in MongoDB −

> db.arrayOfArraysDemo.find({'EmployeeSkills':{$elemMatch:{$elemMatch:{$in:['MongoDB']}}} }).pretty();

The following is the output −

{    "_id" : ObjectId("5c7f7a8d8d10a061296a3c5b"),    "EmployeeName" : "Larry",    "EmployeeSkills" : [       [          "Java",          "MongoDB",          "MySQL",          "SQL Server"       ]    ] }