Update an array element matching a condition using $push in MongoDB

For this, use update command and $push. Let us first create a collection with documents −

>db.demo9.insertOne({"StudentDetails":[{"StudentName":"Chris","ListOfSubject":["MySQL","Java"]}]}); {    "acknowledged" : true,    "insertedId" : ObjectId("5e0f6438d7df943a7cec4f94") }

Following is the query to display all documents from a collection with the help of find() method −

> db.demo9.find().pretty();

This will produce the following output −

{    "_id" : ObjectId("5e0f6438d7df943a7cec4f94"),    "StudentDetails" : [       {          "StudentName" : "Chris",          "ListOfSubject" : [             "MySQL",             "Java"          ]       }    ] }

Following is the query to update an array element matching a condition using $push −

> db.demo9.update( { "StudentDetails.StudentName":"Chris"}, {$push:{"StudentDetails.$.ListOfSubject":"MongoDB"}}); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

Following is the query to display all documents from a collection with the help of find() method −

> db.demo9.find().pretty();

This will produce the following output −

{    "_id" : ObjectId("5e0f6438d7df943a7cec4f94"),    "StudentDetails" : [       {          "StudentName" : "Chris",          "ListOfSubject" : [             "MySQL",             "Java",             "MongoDB"          ]       }    ] }