db.collection.findAndModify()

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Definition
Return Data
Behavior
Examples

Definition

db.collection.findAndModify(document)

Important

mongosh Method

This page documents a mongosh method. This is not the documentation for database commands or language-specific drivers, such as Node.js.

For the database command, see the findAndModify command.

For MongoDB API drivers, refer to the language-specific MongoDB driver documentation.

For the legacy mongo shell documentation, refer to the documentation for the corresponding MongoDB Server release:

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 new option.

Changed in version 5.0.

The findAndModify() method has the following form:

db.collection.findAndModify({
    query: <document>,
    sort: <document>,
    remove: <boolean>,
    update: <document or aggregation pipeline>, // Changed in MongoDB 4.2
    new: <boolean>,
    fields: <document>,
    upsert: <boolean>,
    bypassDocumentValidation: <boolean>,
    writeConcern: <document>,
    maxTimeMS: <integer>,
    collation: <document>,
    arrayFilters: [ <filterdocument1>, ... ],
    let: <document> // Added in MongoDB 5.0
});

The db.collection.findAndModify() method takes a document parameter with the following embedded document fields:

Parameter	Type	Description
`query`	document	Optional. The selection criteria for the modification. The `query` field employs the same query selectors as used in the `db.collection.find()` method. Although the query may match multiple documents, `db.collection.findAndModify()` will only select one document to modify. If unspecified, defaults to an empty document. Starting in MongoDB 4.2 (and 4.0.12+, 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. `db.collection.findAndModify()` modifies the first document in the sort order specified by this argument. Starting in MongoDB 4.2 (and 4.0.12+, 3.6.14+, and 3.4.23+), the operation errors if the sort argument is not a document. MongoDB does not store documents in a collection in a particular order. When sorting on a field which contains duplicate values, documents containing those values may be returned in any order. If consistent sort order is desired, include at least one field in your sort that contains unique values. The easiest way to guarantee this is to include the `_id` field in your sort query. See Sort Consistency for more information.
`remove`	boolean	Must specify either the `remove` or the `update` field. Removes the document specified in the `query` field. Set this to `true` to remove the selected document . The default is `false`.
`update`	document or array	Must specify either the `remove` or the `update` field. Performs an update of the selected document. If passed a document with update operator expressions, `db.collection.findAndModify()` performs the specified modification. If passed a replacement document `{ <field1>: <value1>, ...}`, the `db.collection.findAndModify()` performs a replacement. Starting in MongoDB 4.2, if passed an aggregation pipeline `[ <stage1>, <stage2>, ... ]`, `db.collection.findAndModify()` modifies the document per the pipeline. The pipeline can consist of the following stages: `$addFields` and its alias `$set` `$project` and its alias `$unset` `$replaceRoot` and its alias `$replaceWith`.
`new`	boolean	Optional. When `true`, returns the modified document rather than the original. The default is `false`.
`fields`	document	Optional. A subset of fields to return. The `fields` document specifies an inclusion of a field with `1`, as in: `fields: { <field1>: 1, <field2>: 1, ... }`. Starting in MongoDB 4.2 (and 4.0.12+, 3.6.14+, and 3.4.23+), the operation errors if the fields argument is not a document. For more information on projection, see `fields` Projection.
`upsert`	boolean	Optional. Used in conjunction 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` field(s) are uniquely indexed. See Upsert with Unique Index for an example. Defaults to `false`, which does not insert a new document when no match is found.
`bypassDocumentValidation`	boolean	Optional. Enables `db.collection.findAndModify()` to bypass document validation during the operation. This lets you update documents that do not meet the validation requirements.
`writeConcern`	document	Optional. A document expressing the write concern. Omit to use the default write concern. Do not explicitly set the write concern for the operation if run in a transaction. To use write concern with transactions, see Transactions and Write Concern.
`maxTimeMS`	non-negative integer	Optional. Specifies a time limit in milliseconds. If you do not specify a value for `maxTimeMS`, operations will not time out. A value of `0` explicitly specifies the default unbounded behavior. MongoDB terminates operations that exceed their allotted time limit using the same mechanism as `db.killOp()`. MongoDB only terminates an operation at one of its designated interrupt points.
`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.
`arrayFilters`	array	Optional. An array of filter documents that determine 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 identifier `x` (possibly multiple times), you cannot specify the following for `arrayFilters` that includes 2 separate filter documents for `x`: // INVALID [ { "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: // Example 1 [ { $or: [{"x.a": {$gt: 85}}, {"x.b": {$gt: 80}}] } ] // Example 2 [ { $and: [{"x.a": {$gt: 85}}, {"x.b": {$gt: 80}}] } ] // Example 3 [ { "x.a": { $gt: 85 }, "x.b": { $gt: 80 } } ] For examples, see Specify `arrayFilters` for an Array Update Operations. Note `arrayFilters` is not available for updates that use an aggregation pipeline.
let	document	Optional. Specifies a document with a list of variables. This allows you to improve command readability by separating the variables from the query text. The document syntax is: { <variable_name_1>: <expression_1>, ..., <variable_name_n>: <expression_n> } The variable is set to the value returned by the expression, and cannot be changed afterwards. To access the value of a variable in the command, use the double dollar sign prefix (`$$`) together with your variable name in the form `$$<variable_name>`. For example: `$$targetTotal`. Note To use a variable to filter results, you must access the variable within the `$expr` operator. For a complete example using `let` and variables, see Use Variables in `let`. New in version 5.0.

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 new parameter is not set or is false:
- the pre-modification document if the query matches a document;
- otherwise, null.
If new is true:
- the modified document if the query returns a match;
- the inserted document if upsert: true and no document matches the query;
- otherwise, null.

Behavior

`fields` Projection

Important

Language Consistency

Starting in MongoDB 4.4, as part of making find() and findAndModify() projection consistent with aggregation's $project stage,

The find() and findAndModify() projection can accept aggregation expressions and syntax.
MongoDB enforces additional restrictions with regards to projections. See Projection Restrictions for details.

The fields option takes a document in the following form:

{ field1: <value>, field2: <value> ... }

Projection	Description
`<field>: <1 or true>`	Specifies the inclusion of a field. If you specify a non-zero integer for the projection value, the operation treats the value as `true`.
`<field>: <0 or false>`	Specifies the exclusion of a field.
`"<field>.$": <1 or true>`	Uses the `$` array projection operator to return the first element that matches the query condition on the array field. If you specify a non-zero integer for the projection value, the operation treats the value as `true`. Not available for views.
`<field>: <array projection>`	Uses the array projection operators (`$elemMatch`, `$slice`) to specify the array elements to include. Not available for views.
`<field>: <aggregation expression>`	Specifies the value of the projected field. Starting in MongoDB 4.4, with the use of aggregation expressions and syntax, including the use of literals and aggregation variables, you can project new fields or project existing fields with new values. If you specify a non-numeric, non-boolean literal (such as a literal string or an array or an operator expression) for the projection value, the field is projected with the new value, for example: `{ field: [ 1, 2, 3, "$someExistingField" ] }` `{ field: "New String Value" }` `{ field: { status: "Active", total: { $sum: "$existingArray" } } }` To project a literal value for a field, use the `$literal` aggregation expression, for example: `{ field: { $literal: 5 } }` `{ field: { $literal: true } }` `{ field: { $literal: { fieldWithValue0: 0, fieldWithValue1: 1 } } }` In versions 4.2 and earlier, any specification value (with the exception of the previously unsupported document value) is treated as either `true` or `false` to indicate the inclusion or exclusion of the field. New in version 4.4.

Embedded Field Specification

For fields in an embedded documents, you can specify the field using either:

dot notation, for example "field.nestedfield": <value>
nested form, for example { field: { nestedfield: <value> } } (Starting in MongoDB 4.4)

`_id` Field Projection

The _id field is included in the returned documents by default unless you explicitly specify _id: 0 in the projection to suppress the field.

Inclusion or Exclusion

A projection cannot contain both include and exclude specifications, with the exception of the _id field:

In projections that explicitly include fields, the _id field is the only field that you can explicitly exclude.
In projections that explicitly excludes fields, the _id field is the only field that you can explicitly include; however, the _id field is included by default.

For more information on projection, see also:

Project Fields to Return from Query

Upsert with Unique Index

When using the upsert: true option with the findOneAndUpdate() method, and not using a unique index on the query field(s), multiple instances of a findOneAndUpdate() operation with similar query field(s) could result in duplicate documents being inserted in certain circumstances.

Consider an example where no document with the name Andy exists and multiple clients issue the following command at roughly the same time:

db.people.findAndModify(
   {
     query: { name: "Andy" },
     update: { $inc: { score: 1 } },
     upsert: true
   }
)

If all findOneAndUpdate() operations finish the query phase before any client successfully inserts data, and there is no unique index on the name field, each findOneAndUpdate() operation may result in an insert, creating multiple documents with name: Andy.

To ensure that only one such document is created, and the other findOneAndUpdate() operations update this new document instead, create a unique index on the name field. This guarantees that only one document with name: Andy is permitted in the collection.

With this unique index in place, the multiple findOneAndUpdate() operations now exhibit the following behavior:

Exactly one findOneAndUpdate() operation will successfully insert a new document.
All other findOneAndUpdate() operations will update the newly-inserted document, incrementing the score value.

Sharded Collections

When using findAndModify against a sharded collection, the query must contain an equality condition on shard key.

Starting in version 4.4, documents in a sharded collection can be missing the shard key fields. To target a document that is missing the shard key, you can use the null equality match in conjunction with another filter condition (such as on the _id field). For example:

{ _id: <value>, <shardkeyfield>: null } // _id of the document missing shard key

Shard Key Modification

Starting in MongoDB 4.2, you can update a document's shard key value unless the shard key field is the immutable _id field. In MongoDB 4.2 and earlier, a document's shard key field value is immutable.

Warning

Starting in version 4.4, documents in sharded collections can be missing the shard key fields. Take precaution to avoid accidentally removing the shard key when changing a document's shard key value.

To modify the existing shard key value with db.collection.findAndModify():

You must run on a mongos. Do not issue the operation directly on the shard.
You must run either in a transaction or as a retryable write.
You must include an equality filter on the full shard key.

Missing Shard Key

Starting in version 4.4, documents in a sharded collection can be missing the shard key fields. To use db.collection.findAndModify() to set the document's missing shard key:

You must run on a mongos. Do not issue the operation directly on the shard.
You must run either in a transaction or as a retryable write if the new shard key value is not null.
You must include an equality filter on the full shard key.

Tip

Since a missing key value is returned as part of a null equality match, to avoid updating a null-valued key, include additional query conditions (such as on the _id field) as appropriate.

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, db.collection.findAndModify() and the updateOne() method operate differently:

If multiple documents match the update criteria, for db.collection.findAndModify(), you can specify a sort to provide some measure of control on which document to update.

updateOne() updates the first document that matches.
By default, db.collection.findAndModify() returns the pre-modified version of the document. To obtain the updated document, use the new option.

The updateOne() method returns a WriteResult() object that contains the status of the operation.

To return the updated document, use the find() method. However, other updates may have modified the document between your update and the document retrieval. Also, if the update modified only a single document but multiple documents matched, you will need to use additional logic to identify the updated document.

When modifying a single document, both db.collection.findAndModify() and the updateOne() method atomically update the document. See Atomicity and Transactions for more details about interactions and order of operations of these methods.

Transactions

db.collection.findAndModify() can be used inside multi-document transactions.

Important

In most cases, multi-document transaction incurs a greater performance cost over single document writes, and the availability of multi-document transactions should not be a replacement for effective schema design. For many scenarios, the denormalized data model (embedded documents and arrays) will continue to be optimal for your data and use cases. That is, for many scenarios, modeling your data appropriately will minimize the need for multi-document transactions.

For additional transactions usage considerations (such as runtime limit and oplog size limit), see also Production Considerations.

Upsert within Transactions

Starting in MongoDB 4.4, you can create collections and indexes inside a multi-document transaction if the transaction is not a cross-shard write transaction.

Specifically, in MongoDB 4.4 and greater, db.collection.findAndModify() with upsert: true can be run on an existing collection or a non-existing collection. If run on a non-existing collection, the operation creates the collection.

In MongoDB 4.2 and earlier, the operation must be run on an existing collection.

Tip

Examples

Update and Return

The following method updates and returns an existing document in the people collection where the document matches the query criteria:

db.people.findAndModify({
    query: { name: "Tom", state: "active", rating: { $gt: 10 } },
    sort: { rating: 1 },
    update: { $inc: { score: 1 } }
})

This method performs the following actions:

The query finds a document in the people collection where the name field has the value Tom, the state field has the value active and the rating field has a value greater than 10.
The sort orders the results of the query in ascending order. If multiple documents meet the query condition, the method will select for modification the first document as ordered by this sort.
The update increments the value of the score field by 1.
The method returns the original (i.e. pre-modification) document selected for this update:
```
{
  "_id" : ObjectId("50f1e2c99beb36a0f45c6453"),
  "name" : "Tom",
  "state" : "active",
  "rating" : 100,
  "score" : 5
}
```
To return the modified document, add the new:true option to the method.

If no document matched the query condition, the method returns null.

Upsert

The following method includes the upsert: true option for the update operation to either update a matching document or, if no matching document exists, create a new document:

db.people.findAndModify({
    query: { name: "Gus", state: "active", rating: 100 },
    sort: { rating: 1 },
    update: { $inc: { score: 1 } },
    upsert: true
})

If the method finds a matching document, the method performs an update.

If the method does not find a matching document, the method creates a new document. Because the method included the sort option, it returns an empty document { } as the original (pre-modification) document:

{ }

If the method did not include a sort option, the method returns null.

null

Return New Document

The following method includes both the upsert: true option and the new:true option. The method either updates a matching document and returns the updated document or, if no matching document exists, inserts a document and returns the newly inserted document in the value field.

In the following example, no document in the people collection matches the query condition:

db.people.findAndModify({
    query: { name: "Pascal", state: "active", rating: 25 },
    sort: { rating: 1 },
    update: { $inc: { score: 1 } },
    upsert: true,
    new: true
})

The method returns the newly inserted document:

{
   "_id" : ObjectId("50f49ad6444c11ac2448a5d6"),
   "name" : "Pascal",
   "rating" : 25,
   "score" : 1,
   "state" : "active"
}

Sort and Remove

By including a sort specification on the rating field, the following example removes from the people collection a single document with the state value of active and the lowest rating among the matching documents:

db.people.findAndModify(
   {
     query: { state: "active" },
     sort: { rating: 1 },
     remove: true
   }
)

The method returns the deleted document:

{
   "_id" : ObjectId("52fba867ab5fdca1299674ad"),
   "name" : "XYZ123",
   "score" : 1,
   "state" : "active",
   "rating" : 3
}

Specify Collation

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.findAndModify({
    query: { category: "cafe", status: "a" },
    sort: { category: 1 },
    update: { $set: { status: "Updated" } },
    collation: { locale: "fr", strength: 1 }
});

The operation returns the following document:

{ "_id" : 1, "category" : "café", "status" : "A" }

Specify `arrayFilters` for an Array Update Operations

Note

arrayFilters is not available for updates that use an aggregation pipeline.

Starting in MongoDB 3.6, when updating an array field, you can specify arrayFilters that determine which array elements to update.

Update Elements Match `arrayFilters` Criteria

Note

arrayFilters is not available for updates that use an aggregation pipeline.

Create a collection students with the following documents:

db.students.insertMany( [
   { "_id" : 1, "grades" : [ 95, 92, 90 ] },
   { "_id" : 2, "grades" : [ 98, 100, 102 ] },
   { "_id" : 3, "grades" : [ 95, 110, 100 ] }
] )

To modify all elements that are greater than or equal to 100 in the grades array, use the filtered positional operator $[<identifier>] with the arrayFilters option in the db.collection.findAndModify() method:

db.students.findAndModify({
   query: { grades: { $gte: 100 } },
   update: { $set: { "grades.$[element]" : 100 } },
   arrayFilters: [ { "element": { $gte: 100 } } ]
})

The operation updates the grades field for a single document, and after the operation, the collection has the following documents:

{ "_id" : 1, "grades" : [ 95, 92, 90 ] }
{ "_id" : 2, "grades" : [ 98, 100, 100 ] }
{ "_id" : 3, "grades" : [ 95, 110, 100 ] }

Update Specific Elements of an Array of Documents

Note

arrayFilters is not available for updates that use an aggregation pipeline.

Create a collection students2 with the following documents:

db.students2.insertMany( [
   {
      "_id" : 1,
      "grades" : [
         { "grade" : 80, "mean" : 75, "std" : 6 },
         { "grade" : 85, "mean" : 90, "std" : 4 },
         { "grade" : 85, "mean" : 85, "std" : 6 }
      ]
   },
   {
      "_id" : 2,
      "grades" : [
         { "grade" : 90, "mean" : 75, "std" : 6 },
         { "grade" : 87, "mean" : 90, "std" : 3 },
         { "grade" : 85, "mean" : 85, "std" : 4 }
      ]
   }
] )

The following operation finds a document where the _id field equals 1 and uses the filtered positional operator $[<identifier>] with the arrayFilters to modify the mean for all elements in the grades array where the grade is greater than or equal to 85.

db.students2.findAndModify({
   query: { _id : 1 },
   update: { $set: { "grades.$[elem].mean" : 100 } },
   arrayFilters: [ { "elem.grade": { $gte: 85 } } ]
})

The operation updates the grades field for a single document, and after the operation, the collection has the following documents:

{
   "_id" : 1,
   "grades" : [
      { "grade" : 80, "mean" : 75, "std" : 6 },
      { "grade" : 85, "mean" : 100, "std" : 4 },
      { "grade" : 85, "mean" : 100, "std" : 6 }
   ]
}
{
   "_id" : 2,
   "grades" : [
      { "grade" : 90, "mean" : 75, "std" : 6 },
      { "grade" : 87, "mean" : 90, "std" : 3 },
      { "grade" : 85, "mean" : 85, "std" : 4 }
   ]
}

Use an Aggregation Pipeline for Updates

Starting in MongoDB 4.2, db.collection.findAndModify() can accept an aggregation pipeline for the update. The pipeline can consist of the following stages:

$addFields and its alias $set
$project and its alias $unset
$replaceRoot and its alias $replaceWith.

Using the aggregation pipeline allows for a more expressive update statement, such as expressing conditional updates based on current field values or updating one field using the value of another field(s).

For example, create a collection students2 with the following documents:

db.students2.insertMany( [
   {
      "_id" : 1,
      "grades" : [
         { "grade" : 80, "mean" : 75, "std" : 6 },
         { "grade" : 85, "mean" : 90, "std" : 4 },
         { "grade" : 85, "mean" : 85, "std" : 6 }
      ]
   },
   {
      "_id" : 2,
      "grades" : [
         { "grade" : 90, "mean" : 75, "std" : 6 },
         { "grade" : 87, "mean" : 90, "std" : 3 },
         { "grade" : 85, "mean" : 85, "std" : 4 }
      ]
   }
] )

The following operation finds a document where the _id field equals 1 and uses an aggregation pipeline to calculate a new field total from the grades field:

db.students2.findAndModify( {
   query: {  "_id" : 1 },
   update: [ { $set: { "total" : { $sum: "$grades.grade" } } } ],  // The $set stage is an alias for ``$addFields`` stage
   new: true
} )

Note

The $set used in the pipeline refers to the aggregation stage $set and not the update operator $set.

The operation returns the updated document:

{
   "_id" : 1,
   "grades" : [ { "grade" : 80, "mean" : 75, "std" : 6 }, { "grade" : 85, "mean" : 90, "std" : 4 }, { "grade" : 85, "mean" : 85, "std" : 6 } ],
   "total" : 250
}

Use Variables in `let`

New in version 5.0.

To define variables that you can access elsewhere in the command, use the let option.

Note

To filter results using a variable, you must access the variable within the $expr operator.

Create a collection cakeFlavors:

db.cakeFlavors.insertMany( [
   { _id: 1, flavor: "chocolate" },
   { _id: 2, flavor: "strawberry" },
   { _id: 3, flavor: "cherry" }
] )

The following example defines a targetFlavor variable in let and uses the variable to change the cake flavor from cherry to orange:

db.cakeFlavors.findAndModify( {
   query: {
      $expr: { $eq: [ "$flavor", "$$targetFlavor" ] }
   },
   update: { flavor: "orange" },
   let: { targetFlavor: "cherry" }
} )

← db.collection.find()db.collection.findOne() →

db.collection.findAndModify()

Definition

Important

mongosh Method

Note

Note

Note

Return Data

Behavior

fields Projection

Important

Language Consistency

Embedded Field Specification

_id Field Projection

Inclusion or Exclusion

Upsert with Unique Index

Sharded Collections

Shard Key Modification

Warning

Missing Shard Key

Tip

Document Validation

Comparisons with the update Method

Transactions

Important

Upsert within Transactions

Tip

See also:

Write Concerns and Transactions

Examples

Update and Return

Upsert

Return New Document

Sort and Remove

Specify Collation

Specify arrayFilters for an Array Update Operations

Note

Update Elements Match arrayFilters Criteria

Note

Update Specific Elements of an Array of Documents

Note

Use an Aggregation Pipeline for Updates

Note

Use Variables in let

Note

`fields` Projection

`_id` Field Projection

Comparisons with the `update` Method

Specify `arrayFilters` for an Array Update Operations

Update Elements Match `arrayFilters` Criteria

Use Variables in `let`