Ignore null values in MongoDB documents

To ignore null values in MongoDB, use "$ne" : null in aggregate(). Let us create a collection with documents −

> db.demo722.insertOne(
...    {
...       id:101,
...       details: [
...          { Name:""},
...          { Name: "David"},
...          {Name:null},
...          {Name:"Carol"}
...       ]
...    }
... );
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5eab07d543417811278f5889")
}

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

> db.demo722.find();

This will produce the following output −

{ "_id" : ObjectId("5eab07d543417811278f5889"), "id" : 101, "details" : [ { "Name" : "" }, { "Name" : "David" }, { "Name" : null }, { "Name" : "Carol" } ] }

Following is the query to ignore null values in MongoDB using $ne −

> db.demo722.aggregate([
...    {"$unwind": "$details"},
...
...    {"$match": { "details.Name" :{ "$ne" : null } } }
... ])

This will produce the following output −

{ "_id" : ObjectId("5eab07d543417811278f5889"), "id" : 101, "details" : { "Name" : "" } }
{ "_id" : ObjectId("5eab07d543417811278f5889"), "id" : 101, "details" : { "Name" : "David" } }
{ "_id" : ObjectId("5eab07d543417811278f5889"), "id" : 101, "details" : { "Name" : "Carol" } }