How to update value of a key in a list of a json in MongoDB?

Let us first create a collection with documents

> db.updateListOfKeyValuesDemo.insertOne( { "StudentDetails":[ { "StudentName":"John", "StudentAge":23, "StudentCountryName":"US" }, { "StudentName":"Carol", "StudentAge":24, "StudentCountryName":"UK" }, { "StudentName":"Bob", "StudentAge":22, "StudentCountryName":"AUS" } ] } ); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9b5b759882024390176545") }

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

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

This will produce the following output

{    "_id" : ObjectId("5c9b5b759882024390176545"),    "StudentDetails" : [       {          "StudentName" : "John",          "StudentAge" : 23,          "StudentCountryName" : "US"       },       {          "StudentName" : "Carol",          "StudentAge" : 24,          "StudentCountryName" : "UK"       },       {          "StudentName" : "Bob",          "StudentAge" : 22,          "StudentCountryName" : "AUS"       }    ] }

Following is the query to update value of a key in a list of a json in MongoDB

> var documentFromCollection = db.updateListOfKeyValuesDemo.findOne({ ...    "_id": ObjectId("5c9b5b759882024390176545") ... }); > > documentFromCollection.StudentDetails.forEach(function(updateStudent) { ...    updateStudent.StudentName = "Ramit"; ... }); > db.updateListOfKeyValuesDemo.update( ...    { "_id": documentFromCollection ._id }, ...    { "$set": { "StudentDetails": documentFromCollection.StudentDetails } } ... ); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

Let us check the list of key values has been updated or not

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

This will produce the following output

{    "_id" : ObjectId("5c9b5b759882024390176545"),    "StudentDetails" : [       {          "StudentName" : "Ramit",          "StudentAge" : 23,          "StudentCountryName" : "US"       },       {          "StudentName" : "Ramit",          "StudentAge" : 24,          "StudentCountryName" : "UK"       },       {          "StudentName" : "Ramit",          "StudentAge" : 22,          "StudentCountryName" : "AUS"       }    ] }