Introduction to MongoDB collection.deleteMany() Method

The deleteMany() method is a method for deleting multiple documents in MongoDB. It can delete all documents in a collection that meet the specified conditions. Compared with other deletion methods, the deleteMany() method has the following characteristics:

• It can delete all documents in a collection that meet the specified conditions.
• It can delete documents based on specified conditions.
• It can obtain the result of the deletion operation while deleting documents.

Syntax

The syntax of the deleteMany() method is as follows:

db.collection.deleteMany(
   <filter>,
   {
     writeConcern: <document>,
     collation: <document>
   }
)

Here, db.collection is the collection where the documents to be deleted are located; <filter> is a document representing the deletion conditions; writeConcern and collation are optional parameters.

Use Cases

The deleteMany() method can be used in the following scenarios:

• Delete all documents in a collection.
• Delete documents in a collection based on specified conditions.

Examples

Here are two examples of the deleteMany() method.

Example 1

Suppose we have a collection named products, which stores multiple product information documents. Each document contains fields such as _id, name, price, stock, and status. Now, we need to delete all product information documents where the status field is out_of_stock. We can use the deleteMany() method to achieve this. The example code is as follows:

db.products.deleteMany({ status: "out_of_stock" })

After executing the above code, all documents in the products collection where the status field is out_of_stock will be deleted.

Example 2

Suppose we have a collection named orders, which stores multiple order information documents. Each document contains fields such as _id, product_id, user_id, and quantity. Now, we need to delete all order information documents where the user_id field is 1001. We can use the deleteMany() method to achieve this. The example code is as follows:

db.orders.deleteMany({ user_id: 1001 })

After executing the above code, all documents in the orders collection where the user_id field is 1001 will be deleted.

Conclusion

This article introduces the deleteMany() method in MongoDB, including syntax, use cases, examples, and conclusions. The deleteMany() method is a method for deleting multiple documents, which can delete all documents in a collection that meet the specified conditions. It can be used to delete a collection.