Handling optional/empty data in MongoDB?

In order to handle empty data, you can use $ne operator. Let us create a collection with documents. Following is the query

>db.handlingAndEmptyDataDemo.insertOne({"StudentName":"John","StudentCountryName":""});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c9cbd5ca629b87623db1b12")
}
>db.handlingAndEmptyDataDemo.insertOne({"StudentName":"John","StudentCountryName":null});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c9cbd6ba629b87623db1b13")
}
> db.handlingAndEmptyDataDemo.insertOne({"StudentName":"John"});
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5c9cbd71a629b87623db1b14")
}

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

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

This will produce the following output

{
   "_id" : ObjectId("5c9cbd5ca629b87623db1b12"),
   "StudentName" : "John",
   "StudentCountryName" : ""
}
{
   "_id" : ObjectId("5c9cbd6ba629b87623db1b13"),
   "StudentName" : "John",
   "StudentCountryName" : null
}
{ "_id" : ObjectId("5c9cbd71a629b87623db1b14"), "StudentName" : "John" }

Following is the query to handle empty data using $ne

> db.handlingAndEmptyDataDemo.find({StudentCountryName: {$ne: null}});

This will produce the following output

{ "_id" : ObjectId("5c9cbd5ca629b87623db1b12"), "StudentName" : "John", "StudentCountryName" : "" }