MongoDB $exists Operator

The EXISTS operator is a logical operator that allows you to check the existence of data.

MongoDB provides the $exists operator to check the existence of the field in the specified collection.

Syntax of $exists Operator

{ field: { $exists: boolean }}

If $exists is true, it matches the document that contains the field, and if $exists is false, it returns only the documents that do not contain the field.

Example of $exists Operator

Suppose we want to find all students whose class exists.

db.students.find({"class" : {$exists : true}});