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Delete

The new api provides two methods for removing documents from a collection

deleteOne

Removes a single document from a collection.

Deletion Order

Dbcollection.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

Dbcollection.deleteOne() is not allowed on a capped collection.

Sharded Collections

Dbcollection.deleteOne() operations on a sharded collection must include the shard key or the _id field in the query specification. Ddcollection.deleteOne() operations in a sharded collection which do not contain either the shard key or the _id field return an error.

The following is a simple example on how to execute a call to deleteOne()

var writeResult =  await collection.deleteOne(<String, Object>{});

Note

  • The method returns a WriteResult Object that contains informations on the execution of the operation
  • The method return a Future, so you will need to await for the method (or use .then())
  • The filter parameter is mandatory, even if you want to select all record (<String, Object>{}). This is by design to avoid errors in writing the function (like forgetting the selection)

Parameters

Name Type Mandatory Note Description
selector Map<String, Object> or SelectorBuilder X Specifies deletion criteria using query operators. Specify an empty document { } to delete the first document returned in the collection. If the SelectionBuilder is used, only the filter part is considered
writeConcern WriteConcern A document expressing the write concern. Omit to use the default write concern.
collation CollationOptions 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.
hint String Starting from 4.4 A string that specifies the index (name) to use to support the query predicate. If you specify an index that does not exist, the operation errors.
hintDocument Map<String, Object> Starting from 4.4 A Map that specifies the index (specification document) to use to support the query predicate. It is an alternative way to the hint parameter. If both are specified, the index name is used.

Example using some parameters:

var res = await collection.deleteOne(<String, Object>{
          'points': {r'$lte': 20},
          'status': 'P'
        }, writeConcern: WriteConcern(w: 'majority', wtimeout: 5000),
        collation: CollationOptions('fr', strength: 1));

Example using hintDocument:

var res = await collection.deleteOne(<String, Object>{
          'points': {r'$lte': 20},
          'status': 'P'
        }, hintDocument: {'status': 1});

Output

Returns a WriteResult element.

deleteMany

Removes all documents that match the filter from a collection.

Capped Collections (deleteMany)

Dbcollection.deleteMany() is not allowed on a capped collection.

Delete a Single Document

To delete a single document, use Dbcollection.deleteOne() instead. Alternatively, use a field that is a part of a unique index such as _id.

The following is a simple example on how to execute a call to deleteMany()

var writeResult =  await collection.deleteMany(<String, Object>{});

Note

  • The method returns a WriteResult Object that contains informations on the execution of the operation
  • The method return a Future, so you will need to await for the method (or use .then())
  • The filter parameter is mandatory, even if you want to select all record (<String, Object>{}). This is by design to avoid errors in writing the function (like forgetting the selection)

Parameters (deleteMany)

Name Type Mandatory Note Description
selector Map<String, Object> or SelectorBuilder X Specifies deletion criteria using query operators. Specify an empty document { } to delete the first document returned in the collection. If the SelectionBuilder is used, only the filter part is considered
writeConcern WriteConcern A document expressing the write concern. Omit to use the default write concern.
collation CollationOptions 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.
hint String Starting from 4.4 A string that specifies the index (name) to use to support the query predicate. If you specify an index that does not exist, the operation errors.
hintDocument Map<String, Object> Starting from 4.4 A Map that specifies the index (specification document) to use to support the query predicate. It is an alternative way to the hint parameter. If both are specified, the index name is used.

Example using some parameters:

var res = await collection.deleteMany(<String, Object>{
          'points': {r'$lte': 20},
          'status': 'P'
        }, writeConcern: WriteConcern(w: 'majority', wtimeout: 5000),
        collation: CollationOptions('fr', strength: 1));

Example using hintDocument:

var res = await collection.deleteMany(<String, Object>{
          'points': {r'$lte': 20},
          'status': 'P'
        }, hintDocument: {'status': 1});

Output (deleteMany)

Returns a WriteResult element