How to Delete Documents with Condition in MongoDB

In MongoDB, you delete documents that match a condition using deleteOne() to remove a single matching document or deleteMany() to remove all matching documents. You specify the condition as a filter object inside these methods to target the documents you want to delete.

Syntax

The basic syntax to delete documents with a condition uses either deleteOne(filter) or deleteMany(filter). The filter is an object that describes the condition documents must meet to be deleted.

• deleteOne(filter): Deletes the first document that matches the filter.
• deleteMany(filter): Deletes all documents that match the filter.

mongodb

db.collection.deleteOne({ <condition> })
db.collection.deleteMany({ <condition> })

Example

This example shows how to delete documents from a users collection where the age is less than 18. It deletes all such documents using deleteMany().

mongodb

db.users.deleteMany({ age: { $lt: 18 } })

Output

{ "acknowledged" : true, "deletedCount" : 3 }

Common Pitfalls

Common mistakes include:

• Using deleteOne() when you want to delete multiple documents, which only deletes one.
• Not specifying a filter, which deletes all documents if you use deleteMany({}) unintentionally.
• Using incorrect filter syntax, causing no documents to be deleted.

mongodb

/* Wrong: deletes only one document but you want all */
db.users.deleteOne({ age: { $lt: 18 } })

/* Right: deletes all matching documents */
db.users.deleteMany({ age: { $lt: 18 } })

Quick Reference

Use this quick guide to choose the right delete method:

Method	Description	Deletes
deleteOne(filter)	Deletes the first document matching the filter	One document
deleteMany(filter)	Deletes all documents matching the filter	Multiple documents

Key Takeaways

Use deleteOne() to remove a single document matching the condition.

Use deleteMany() to remove all documents matching the condition.

Always specify a filter to avoid deleting unintended documents.

Check the deletion result to confirm how many documents were removed.

Incorrect filter syntax can cause no documents to be deleted.