mongodbHow to check if array is empty in MongoDB?

To check if an array is empty in MongoDB, you can use the $size operator. This operator returns the number of elements in an array. If the array is empty, the $size operator will return 0.

Example code

db.collection.find( { arrayField: { $size: 0 } } )

Output example

{ "_id" : ObjectId("5f3d7f9f8f9f9f9f9f9f9f9f"), "arrayField" : [] }

Code explanation

• db.collection.find(): This is the MongoDB command to query a collection.
• { arrayField: { $size: 0 } }: This is the query condition to check if the array is empty. The $size operator returns the number of elements in an array. If the array is empty, the $size operator will return 0.

Helpful links

• MongoDB Documentation - $size

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