In this chapter, we will learn how to delete a document using MongoDB.
The remove() Method
MongoDB’s remove() method is used to remove a document from the collection. remove() method accepts two parameters. One is deletion criteria and the second is just one flag.
- deletion criteria − (Optional) deletion criteria according to documents will be removed.
- justOne − (Optional) if set to true or 1, then remove only one document.
Syntax
The basic syntax of the remove() method is as follows −
>db.COLLECTION_NAME.remove(DELLETION_CRITTERIA)
Example
Consider the mycol collection has the following data.
{_id : ObjectId("507f191e810c19729de860e1"), title: "MongoDB Overview"},
{_id : ObjectId("507f191e810c19729de860e2"), title: "NoSQL Overview"},
{_id : ObjectId("507f191e810c19729de860e3"), title: "Adglob Overview"}
The following example will remove all the documents whose title is ‘MongoDB Overview’.
>db.mycol.remove({'title':'MongoDB Overview'})
WriteResult({"nRemoved" : 1})
> db.mycol.find()
{"_id" : ObjectId("507f191e810c19729de860e2"), "title" : "NoSQL Overview" }
{"_id" : ObjectId("507f191e810c19729de860e3"), "title" : "Adglob Overview" }
Remove Only One
If there are multiple records and you want to delete only the first record, then set justOne parameter in the remove() method.
>db.COLLECTION_NAME.remove(DELETION_CRITERIA,1)
Remove All Documents
If you don’t specify deletion criteria, then MongoDB will delete whole documents from the collection. This is equivalent to SQL’s truncate command.
> db.mycol.remove({})
WriteResult({ "nRemoved" : 2 })
> db.mycol.find()
>
