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findAndModify
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Definition
findAndModify
-
The
findAndModify
command modifies and returns a single document. By default, the returned document does not include the modifications made on the update. To return the document with the modifications made on the update, use thenew
option.The command has the following syntax:
{ findAndModify: <collection-name>, query: <document>, sort: <document>, remove: <boolean>, update: <document>, new: <boolean>, fields: <document>, upsert: <boolean>, bypassDocumentValidation: <boolean>, writeConcern: <document>, collation: <document>, arrayFilters: <array> }
The
findAndModify
command takes the following fields:Field Type Description query
document Optional. The selection criteria for the modification. The
query
field employs the same query selectors as used in thedb.collection.find()
method. Although the query may match multiple documents,findAndModify
will only select one document to modify.If unspecified, defaults to an empty document.
Starting in MongoDB 3.6.14+ (and 3.4.23+), the operation errors if the query argument is not a document.
sort
document Optional. Determines which document the operation modifies if the query selects multiple documents.
findAndModify
modifies the first document in the sort order specified by this argument.Starting in MongoDB 3.6.14+ (and 3.4.23+), the operation errors if the sort argument is not a document.
remove
boolean Must specify either the remove
or theupdate
field. Removes the document specified in thequery
field. Set this totrue
to remove the selected document . The default isfalse
.update
document Must specify either the remove
or theupdate
field. Performs an update of the selected document. Theupdate
field employs the same update operators orfield: value
specifications to modify the selected document.new
boolean Optional. When true
, returns the modified document rather than the original. ThefindAndModify
method ignores thenew
option forremove
operations. The default isfalse
.fields
document Optional. A subset of fields to return. The
fields
document specifies an inclusion of a field with1
, as in:fields: { <field1>: 1, <field2>: 1, ... }
. See projection.Starting in MongoDB 3.6.14+ (and 3.4.23+), the operation errors if the fields argument is not a document.
upsert
boolean Optional. Used in conjuction with the
update
field.When
true
,findAndModify()
either:- Creates a new document if no documents match the
query
. For more details see upsert behavior. - Updates a single document that matches the
query
.
To avoid multiple upserts, ensure that the
query
fields are uniquely indexed.Defaults to
false
.bypassDocumentValidation
boolean Optional. Enables
findAndModify
to bypass document validation during the operation. This lets you update documents that do not meet the validation requirements.New in version 3.2.
writeConcern
document Optional. A document expressing the write concern. Omit to use the default write concern.
New in version 3.2.
maxTimeMS
integer Optional. Specifies a time limit in milliseconds for processing the operation. findAndModify
string The collection against which to run the command. 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.
arrayFilters
array Optional. An array of filter documents that determines which array elements to modify for an update operation on an array field.
In the update document, use the
$[<identifier>]
filtered positional operator to define an identifier, which you then reference in the array filter documents. You cannot have an array filter document for an identifier if the identifier is not included in the update document.Note
The
<identifier>
must begin with a lowercase letter and contain only alphanumeric characters.You can include the same identifier multiple times in the update document; however, for each distinct identifier (
$[identifier]
) in the update document, you must specify exactly one corresponding array filter document. That is, you cannot specify multiple array filter documents for the same identifier. For example, if the update statement includes the identifierx
(possibly multiple times), you cannot specify the following forarrayFilters
that includes 2 separate filter documents forx
:[ { "x.a": { $gt: 85 } }, { "x.b": { $gt: 80 } } ]
However, you can specify compound conditions on the same identifier in a single filter document, such as in the following examples:
[ { $or: [{"x.a": {$gt: 85}}, {"x.b": {$gt: 80}}] } ] [ { $and: [{"x.a": {$gt: 85}}, {"x.b": {$gt: 80}}] } ] [ { "x.a": { $gt: 85 }, "x.b": { $gt: 80 } } ]
For examples, see Specify arrayFilters for an Array Update Operations.
New in version 3.6.
- Creates a new document if no documents match the
Output
The findAndModify
command returns a document with the following fields:
Field | Type | Description |
---|---|---|
value |
document | Contains the command’s returned value. See value for details. |
lastErrorObject |
document | Contains information about updated documents. See lastErrorObject for details. |
ok |
number | Contains the command’s execution status. 1 on success, or 0 if an error occurred. |
lastErrorObject
The lastErrorObject
embedded document contains the following fields:
Field | Type | Description |
---|---|---|
updatedExisting |
boolean | Contains true if an update operation modified an existing document. |
upserted |
document | Contains the ObjectId of the inserted document if an update operation with upsert: true resulted in a new document. |
value
For remove
operations, value
contains the removed document if the query matches a document. If the query does not match a document to remove, value
contains null
.
For update
operations, the value
embedded document contains the following:
- If the
new
parameter is not set or isfalse
:- the pre-modification document if the query matches a document;
- otherwise,
null
.
- If
new
istrue
:- the modified document if the query returns a match;
- the inserted document if
upsert: true
and no document matches the query; - otherwise,
null
.
Changed in version 3.0: In previous versions, if for the update, sort
is specified, and upsert: true
, and the new
option is not set or new: false
, findAndModify
returns an empty document {}
in the value
field instead of null
.
Behavior
Upsert and Unique Index
When the findAndModify
command includes the upsert: true
option and the query field(s) is not uniquely indexed, the command could insert a document multiple times in certain circumstances.
Consider an example where no document with the name Andy
exists and multiple clients issue the following command:
db.runCommand(
{
findAndModify: "people",
query: { name: "Andy" },
sort: { rating: 1 },
update: { $inc: { score: 1 } },
upsert: true
}
)
If all the commands finish the query
phase before any command starts the modify
phase, and there is no unique index on the name
field, the commands may each perform an upsert, creating multiple duplicate documents.
To prevent the creation of multiple duplicate documents, create a unique index on the name
field. With the unique index in place, then the multiple findAndModify
commands will exhibit one of the following behaviors:
- Exactly one
findAndModify
successfully inserts a new document. - Zero or more
findAndModify
commands update the newly inserted document. - Zero or more
findAndModify
commands fail when they attempt to insert a duplicate. If the command fails due to a unique index constraint violation, you can retry the command. Absent a delete of the document, the retry should not fail.