How to check if field is a number in MongoDB?

To check if field is a number in MongoDB, use the $type operator. Following is the syntax

db.yourCollectionName.find({youtFieldName: {$type:"number"}}).pretty();

Let us first create a collection with documents

> db.checkIfFieldIsNumberDemo.insertOne({"StudentName":"John","StudentAge":23}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9ec75dd628fa4220163b83") } >db.checkIfFieldIsNumberDemo.insertOne({"StudentName":"Chris","StudentMathScore":98,"StudentCountryName":"US"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9ec77cd628fa4220163b84") } >db.checkIfFieldIsNumberDemo.insertOne({"StudentName":"Robert","StudentCountryName":"AUS"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9ec7a4d628fa4220163b85") } >db.checkIfFieldIsNumberDemo.insertOne({"StudentId":101,"StudentName":"Larry","StudentCountryName":"AUS"}); {    "acknowledged" : true,    "insertedId" : ObjectId("5c9ec7ccd628fa4220163b86") }

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

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

This will produce the following output

{    "_id" : ObjectId("5c9ec75dd628fa4220163b83"),    "StudentName" : "John",    "StudentAge" : 23 } {    "_id" : ObjectId("5c9ec77cd628fa4220163b84"),    "StudentName" : "Chris",    "StudentMathScore" : 98,    "StudentCountryName" : "US" } {    "_id" : ObjectId("5c9ec7a4d628fa4220163b85"),    "StudentName" : "Robert",    "StudentCountryName" : "AUS" } {    "_id" : ObjectId("5c9ec7ccd628fa4220163b86"),    "StudentId" : 101,    "StudentName" : "Larry",    "StudentCountryName" : "AUS" }

Following is the query to check if a field is a number

> db.checkIfFieldIsNumberDemo.find({StudentMathScore: {$type:"number"}}).pretty();

The following is the output displaying the field which is a number i.e. StudentMathScore

{    "_id" : ObjectId("5c9ec77cd628fa4220163b84"),    "StudentName" : "Chris",    "StudentMathScore" : 98,    "StudentCountryName" : "US" }