Find document that matches same array elements in MongoDB?

To find a document that matches the same array elements, use find() and within that, use $all. The $all operator selects the documents where the value of a field is an array that contains all the specified elements.

Let us create a collection with documents −

> db.demo543.insertOne({id:101, subject:["MySQL", "Java" ,"C","Python"]});{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e8e1b2f9e5f92834d7f05c9")
}
> db.demo543.insertOne({id:102, subject:["MySQL", "MongoDB" ,"SQL Server"]});{
   "acknowledged" : true,
   "insertedId" : ObjectId("5e8e1b2f9e5f92834d7f05ca")
}

Display all documents from a collection with the help of find() method −

> db.demo543.find();

This will produce the following output −

{ "_id" : ObjectId("5e8e1b2f9e5f92834d7f05c9"), "id" : 101, "subject" : [ "MySQL", "Java", "C", "Python" ] }
{ "_id" : ObjectId("5e8e1b2f9e5f92834d7f05ca"), "id" : 102, "subject" : [ "MySQL", "MongoDB", "SQL Server" ] }

Following is the query to find a document that matches the same array elements in MongoDB −

> db.demo543.find({
...    "subject": { $all: [ "MySQL", "MongoDB", "SQL Server"], $size: 3 }
... })

This will produce the following output −

{ "_id" : ObjectId("5e8e1b2f9e5f92834d7f05ca"), "id" : 102, "subject" : [ "MySQL", "MongoDB", "SQL Server" ] }