Add a field to an embedded document in an array in MongoDB?

You can use update() along with $ operator for this. Let us first create a collection with documents −

> db.addAFieldDemo.insertOne( ...   { ... ...      "ClientName" : "Larry", ...      "ClientCountryName" : "US", ...      "ClientOtherDetails" : [ ...         { ...            "ClientProjectName":"Online Banking System" ...         } ...      ] ...   } ... ); {    "acknowledged" : true,    "insertedId" : ObjectId("5cd44bdc2cba06f46efe9ee8") }

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

>  db.addAFieldDemo.find().pretty();

This will produce the following output −

{    "_id" : ObjectId("5cd44bdc2cba06f46efe9ee8"),    "ClientName" : "Larry",    "ClientCountryName" : "US",    "ClientOtherDetails" : [       {          "ClientProjectName" : "Online Banking System"       }    ] }

Following is the query to add a field to an embedded document in an array −

> db.addAFieldDemo.update({ClientOtherDetails:{$elemMatch:{"ClientProjectName" : "Online Banking System"}}}, ... {$set :{'ClientOtherDetails.$.isMarried':true}},true); WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

Let us display all the documents from the above collection −

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

This will produce the following output −

{    "_id" : ObjectId("5cd44bdc2cba06f46efe9ee8"),    "ClientName" : "Larry",    "ClientCountryName" : "US",    "ClientOtherDetails" : [       {          "ClientProjectName" : "Online Banking System",          "isMarried" : true       }    ] }