Let us first create a collection with documents −
> db.arrayContainOnlySpecificFieldDemo.insertOne( ... { ... "StudentName":"John", ... "StudentAge":21, ... "StudentTechnicalSubject":["C","Java","MongoDB"] ... } ... ); { "acknowledged" : true, "insertedId" : ObjectId("5cc4921dac184d684e3fa26a") } > db.arrayContainOnlySpecificFieldDemo.insertOne( { "StudentName":"Carol", "StudentAge":23, "StudentTechnicalSubject":["MongoDB"] } ); { "acknowledged" : true, "insertedId" : ObjectId("5cc49237ac184d684e3fa26b") }
Display all documents from a collection with the help of find() method. The query is as follows −
> db.arrayContainOnlySpecificFieldDemo.find().pretty();
This will produce the following output −
{ "_id" : ObjectId("5cc4921dac184d684e3fa26a"), "StudentName" : "John", "StudentAge" : 21, "StudentTechnicalSubject" : [ "C", "Java", "MongoDB" ] } { "_id" : ObjectId("5cc49237ac184d684e3fa26b"), "StudentName" : "Carol", "StudentAge" : 23, "StudentTechnicalSubject" : [ "MongoDB" ] }
Following is the query to select objects where an array contains only a specific field −
> db.arrayContainOnlySpecificFieldDemo.find({"StudentTechnicalSubject":[ "MongoDB"]}).pretty();
This will produce the following output −
{ "_id" : ObjectId("5cc49237ac184d684e3fa26b"), "StudentName" : "Carol", "StudentAge" : 23, "StudentTechnicalSubject" : [ "MongoDB" ] }