# How do I check whether a field contains null value in MongoDB?

MongoDBDatabaseBig Data Analytics

You can use $type operator to check whether a filed contains null value. Let us first create a collection with documents. We have also inserted a null in a field − > db.nullDemo.insertOne({"FirstName":"Chris"}); { "acknowledged" : true, "insertedId" : ObjectId("5cc68a1eac184d684e3fa270") } > db.nullDemo.insertOne({"FirstName":null}); { "acknowledged" : true, "insertedId" : ObjectId("5cc68a25ac184d684e3fa271") } > db.nullDemo.insertOne({"FirstName":"Robert"}); { "acknowledged" : true, "insertedId" : ObjectId("5cc68a2cac184d684e3fa272") } Following is the query to display all documents from a collection with the help of find() method − > db.nullDemo.find().pretty(); This will produce the following output. One of the field is null − { "_id" : ObjectId("5cc68a1eac184d684e3fa270"), "FirstName" : "Chris" } { "_id" : ObjectId("5cc68a25ac184d684e3fa271"), "FirstName" : null } { "_id" : ObjectId("5cc68a2cac184d684e3fa272"), "FirstName" : "Robert" } Here is the query to check whether a field contains null value. The field “FirstName” is checked − > db.nullDemo.find( { FirstName: {$type: 10 } } );

This will produce the following output −

{ "_id" : ObjectId("5cc68a25ac184d684e3fa271"), "FirstName" : null }
Published on 21-May-2019 08:27:41