Use $slice operator for this. Let us first create a collection with documents −
> db.gettingFirstItemInArrayDemo.insertOne( { "UserId": 101, "UserName":"Carol", "UserOtherDetails": [ {"UserFriendName":"Sam"}, {"UserFriendName":"Mike"}, {"UserFriendName":"David"}, {"UserFriendName":"Bob"} ] } ); { "acknowledged" : true, "insertedId" : ObjectId("5cdfca52bf3115999ed51205") }
Following is the query to display all documents from a collection with the help of find() method −
> db.gettingFirstItemInArrayDemo.find().pretty();
This will produce the following output −
{ "_id" : ObjectId("5cdfca52bf3115999ed51205"), "UserId" : 101, "UserName" : "Carol", "UserOtherDetails" : [ { "UserFriendName" : "Sam" }, { "UserFriendName" : "Mike" }, { "UserFriendName" : "David" }, { "UserFriendName" : "Bob" } ] }
Following is the query to get only the first item for an array property in MongoDB −
> db.gettingFirstItemInArrayDemo.find({"UserId":101}, {UserOtherDetails:{$slice: 1}});
This will produce the following output −
{ "_id" : ObjectId("5cdfca52bf3115999ed51205"), "UserId" : 101, "UserName" : "Carol", "UserOtherDetails" : [ { "UserFriendName" : "Sam" } ] }