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db.collection.findAndModify()
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Definition
db.collection.findAndModify( document )-
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 the
newoption. ThefindAndModify()method is a shell helper around thefindAndModifycommand.The
findAndModify()method has the following form:Changed in version 3.6.
db.collection.findAndModify({ query: <document>, sort: <document>, remove: <boolean>, update: <document>, new: <boolean>, fields: <document>, upsert: <boolean>, bypassDocumentValidation: <boolean>, writeConcern: <document>, collation: <document>, arrayFilters: [ <filterdocument1>, ... ] });The
db.collection.findAndModify()method takes a document parameter with the following embedded document fields:Parameter Type Description querydocument Optional. The selection criteria for the modification. The
queryfield 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.
sortdocument 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.
removeboolean Must specify either the removeor theupdatefield. Removes the document specified in thequeryfield. Set this totrueto remove the selected document . The default isfalse.updatedocument Must specify either the removeor theupdatefield. Performs an update of the selected document. Theupdatefield employs the same update operators orfield: valuespecifications to modify the selected document.newboolean Optional. When true, returns the modified document rather than the original. ThefindAndModify()method ignores thenewoption forremoveoperations. The default isfalse.fieldsdocument Optional. A subset of fields to return. The
fieldsdocument 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.
upsertboolean Optional. Used in conjuction with the
updatefield.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
queryfields are uniquely indexed.Defaults to
false.bypassDocumentValidationboolean Optional. Enables
db.collection.findAndModifyto bypass document validation during the operation. This lets you update documents that do not meet the validation requirements.New in version 3.2.
writeConcerndocument Optional. A document expressing the write concern. Omit to use the default write concern.
New in version 3.2.
maxTimeMSinteger Optional. Specifies a time limit in milliseconds for processing the operation. collationdocument 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
localefield 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.
arrayFiltersarray 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 forarrayFiltersthat 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
Return Data
For remove operations, if the query matches a document, findAndModify() returns the removed document. If the query does not match a document to remove, findAndModify() returns null.
For update operations, findAndModify() returns one of the following:
- If the
newparameter is not set or isfalse:- the pre-modification document if the query matches a document;
- otherwise,
null.
- If
newistrue:- the modified document if the query returns a match;
- the inserted document if
upsert: trueand 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, db.collection.findAndModify() returns an empty document {} instead of null.
Behavior
Upsert and Unique Index
When findAndModify() includes the upsert: true option and the query field(s) is not uniquely indexed, the method could insert a document multiple times in certain circumstances.
In the following example, no document with the name Andy exists, and multiple clients issue the following command:
db.people.findAndModify({
query: { name: "Andy" },
sort: { rating: 1 },
update: { $inc: { score: 1 } },
upsert: true
})
Then, if these clients’ findAndModify() methods finish the query phase before any command starts the modify phase, and there is no unique index on the name field, the commands may all perform an upsert, creating multiple duplicate documents.
To prevent the creation of multiple duplicate documents with the same name, create a unique index on the name field. With this unique index in place, the multiple methods will exhibit one of the following behaviors:
- Exactly one
findAndModify()successfully inserts a new document. - Zero or more
findAndModify()methods update the newly inserted document. - Zero or more
findAndModify()methods fail when they attempt to insert documents with the same name. If the method fails due to the unique index constraint violation on thenamefield, you can retry the method. Absent a delete of the document, the retry should not fail.
Document Validation
The db.collection.findAndModify() method adds support for the bypassDocumentValidation option, which lets you bypass document validation when inserting or updating documents in a collection with validation rules.
Comparisons with the update Method
When updating a document, findAndModify() and the update() method operate differently:
By default, both operations modify a single document. However, the
update()method with itsmultioption can modify more than one document.