db.collection.deleteOne()¶

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Definition¶

db.collection.deleteOne()¶

Removes a single document from a collection.

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

Parameter Type Description

filter

document

Specifies deletion criteria using query operators.

Specify an empty document { } to delete the first document returned in the collection.

writeConcern document Optional. A document expressing the write concern. Omit to use the default write concern.

collation

document

Optional.

Specifies the collation to use for the operation.

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

The collation option has the following syntax:

collation: {
   locale: <string>,
   caseLevel: <boolean>,
   caseFirst: <string>,
   strength: <int>,
   numericOrdering: <boolean>,
   alternate: <string>,
   maxVariable: <string>,
   backwards: <boolean>
}

When specifying collation, the locale field is mandatory; all other collation fields are optional. For descriptions of the fields, see Collation Document.

If the collation is unspecified but the collection has a default collation (see db.createCollection()), the operation uses the collation specified for the collection.

If no collation is specified for the collection or for the operations, MongoDB uses the simple binary comparison used in prior versions for string comparisons.

You cannot specify multiple collations for an operation. For example, you cannot specify different collations per field, or if performing a find with a sort, you cannot use one collation for the find and another for the sort.

New in version 3.4.

Returns:	A document containing: A boolean `acknowledged` as `true` if the operation ran with write concern or `false` if write concern was disabled `deletedCount` containing the number of deleted documents

Behavior¶

Deletion Order¶

deleteOne deletes the first document that matches the filter. Use a field that is part of a unique index such as _id for precise deletions.

Capped Collections¶

deleteOne() throws a WriteError exception if used on a capped collection. To remove documents from a capped collection, use db.collection.drop() instead.

Examples¶

Delete a Single Document¶

The orders collection has documents with the following structure:

{
   _id: ObjectId("563237a41a4d68582c2509da"),
   stock: "Brent Crude Futures",
   qty: 250,
   type: "buy-limit",
   limit: 48.90,
   creationts: ISODate("2015-11-01T12:30:15Z"),
   expiryts: ISODate("2015-11-01T12:35:15Z"),
   client: "Crude Traders Inc."
}

The following operation deletes the order with _id: ObjectId("563237a41a4d68582c2509da") :

try {
   db.orders.deleteOne( { "_id" : ObjectId("563237a41a4d68582c2509da") } );
} catch (e) {
   print(e);
}

The operation returns:

{ "acknowledged" : true, "deletedCount" : 1 }

The following operation deletes the first document with expiryts greater than ISODate("2015-11-01T12:40:15Z")

try {
   db.orders.deleteOne( { "expiryts" : { $lt: ISODate("2015-11-01T12:40:15Z") } } );
} catch (e) {
   print(e);
}

The operation returns:

{ "acknowledged" : true, "deletedCount" : 1 }

deleteOne() with Write Concern¶

Given a three member replica set, the following operation specifies a w of majority, wtimeout of 100:

try {
   db.orders.deleteOne(
       { "_id" : ObjectId("563237a41a4d68582c2509da") },
       { w : "majority", wtimeout : 100 }
   );
} catch (e) {
   print (e);
}

If the acknowledgement takes longer than the wtimeout limit, the following exception is thrown:

WriteConcernError({
   "code" : 64,
   "errInfo" : {
      "wtimeout" : true
   },
   "errmsg" : "waiting for replication timed out"
})

Specify Collation¶

New in version 3.4.

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

A collection myColl has the following documents:

{ _id: 1, category: "café", status: "A" }
{ _id: 2, category: "cafe", status: "a" }
{ _id: 3, category: "cafE", status: "a" }

The following operation includes the collation option:

db.myColl.deleteOne(
   { category: "cafe", status: "A" },
   { collation: { locale: "fr", strength: 1 } }
)