> For the complete MongoDB documentation index, see www.mongodb.com/docs/llms.txt

# findAndModify (database command)

## Definition

Updates and returns a single document. By default, the returned document does not include the modifications made by the update. To return the modified document, use the `new` option.

**Tip:**

In [`mongosh`](https://www.mongodb.com/docs/mongodb-shell.md#std-program-mongosh), this command can also be run through the [`db.collection.findAndModify()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.findandmodify.md#mongodb-method-db.collection.findAndModify) helper method.

Helper methods are convenient for [`mongosh`](https://www.mongodb.com/docs/mongodb-shell.md#std-program-mongosh) users, but they may not return the same level of information as database commands.  In cases where the convenience is not needed or the additional return fields are required, use the database command.

## Compatibility

This command is available in deployments hosted in the following environments:

- [MongoDB Atlas](https://www.mongodb.com/docs/atlas): The fully managed service for MongoDB deployments in the cloud

**Note:**

This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, see [Unsupported Commands.](https://www.mongodb.com/docs/atlas/unsupported-commands/)

- [MongoDB Enterprise](https://www.mongodb.com/docs/manual/administration/install-enterprise.md#std-label-install-mdb-enterprise): The subscription-based, self-managed version of MongoDB

- [MongoDB Community](https://www.mongodb.com/docs/manual/administration/install-community.md#std-label-install-mdb-community-edition): The source-available, free-to-use, and self-managed version of MongoDB

**Changed in version 5.0**

## Syntax

The command has the following syntax:

```javascript
db.runCommand(
   {
     findAndModify: <collection-name>,
     query: <document>,
     sort: <document>,
     remove: <boolean>,
     update: <document or aggregation pipeline>,
     new: <boolean>,
     fields: <document>,
     upsert: <boolean>,
     bypassDocumentValidation: <boolean>,
     writeConcern: <document>,
     maxTimeMS: <integer>,
     collation: <document>,
     arrayFilters: <array>,
     hint: <document|string>,
     comment: <any>,
     let: <document> // Added in MongoDB 5.0
   }
)
```

## Command Fields

The 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](https://www.mongodb.com/docs/manual/reference/mql/query-predicates.md#std-label-query-selectors) as used in the [`db.collection.find()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.find.md#mongodb-method-db.collection.find) method. Although the query may match multiple documents, [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) **selects only one document to update**. If unspecified, defaults to an empty document. If the query argument is not a document, the operation errors. |
| `sort` | document | Optional. Determines which document the operation updates if the query selects multiple documents. [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) updates the first document in the sort order specified by this argument. If the sort argument is not a document, the operation errors. 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. The `$sort` operation is not a "stable sort," which means that documents with equivalent sort keys are not guaranteed to remain in the same relative order in the output as they were in the input. If the field specified in the sort criteria does not exist in two documents, then the value on which they are sorted is the same. The two documents may be returned in any order. If consistent sort order is desired, include at least one field in your sort that contains unique values. The easiest way to guarantee this is to include the `_id` field in your sort query. See [Sort Consistency](https://www.mongodb.com/docs/manual/reference/method/cursor.sort.md#std-label-sort-cursor-consistent-sorting) for more information. |
| `remove` | boolean | Must specify either the `remove` or the `update` field. Removes the document specified in the `query` field. Set this to `true` to remove the selected document . The default is `false`. |
| `update` | document or array | Must specify either the `remove` or the `update` field. Performs an update of the selected document. If passed a document with [update operator expressions](https://www.mongodb.com/docs/manual/reference/mql/update.md#std-label-update-operators), [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) performs the specified modification.; If passed a replacement document `{ <field1>: <value1>, ...}`, the [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) performs a replacement.; If passed an [aggregation pipeline](https://www.mongodb.com/docs/manual/core/aggregation-pipeline.md#std-label-aggregation-pipeline) `[ <stage1>, <stage2>, ... ]`, [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) updates the document per the pipeline. The pipeline can consist of the following stages:[`$addFields`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/addfields.md#mongodb-pipeline-pipe.-addFields) and its alias [`$set`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/set.md#mongodb-pipeline-pipe.-set); [`$project`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/project.md#mongodb-pipeline-pipe.-project) and its alias [`$unset`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/unset.md#mongodb-pipeline-pipe.-unset); [`$replaceRoot`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/replaceroot.md#mongodb-pipeline-pipe.-replaceRoot) and its alias [`$replaceWith`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/replacewith.md#mongodb-pipeline-pipe.-replaceWith) |
| `new` | boolean | Optional. When `true`, returns the updated 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, ... }`. See [Projection.](https://www.mongodb.com/docs/manual/reference/method/db.collection.find.md#std-label-find-projection) If the fields argument is not a document, the operation errors. |
| `upsert` | boolean | Optional. Used in conjunction with the `update` field. When `true`, [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) either: Creates a new document if no documents match the `query`. For more details see [upsert behavior.](https://www.mongodb.com/docs/manual/reference/method/db.collection.update.md#std-label-upsert-behavior); Updates a single document that matches the `query`. To avoid multiple [upserts](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-upsert), ensure that the `query` field(s) are [uniquely indexed](https://www.mongodb.com/docs/manual/core/index-unique.md#std-label-index-type-unique). See [Upsert with Unique Index](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#std-label-upsert-and-unique-index-dbcommand) for an example. Defaults to `false`, which does *not* insert a new document when no match is found. |
| `bypassDocumentValidation` | boolean | Optional. Enables [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) to bypass schema validation during the operation. This lets you update documents that do not meet the validation requirements. |
| `writeConcern` | document | Optional. Specifies the [write concern](https://www.mongodb.com/docs/manual/reference/write-concern.md#std-label-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.](https://www.mongodb.com/docs/manual/core/transactions.md#std-label-transactions-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()`](https://www.mongodb.com/docs/manual/reference/method/db.killop.md#mongodb-method-db.killOp). MongoDB only terminates an operation at one of its designated [interrupt points.](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-interrupt-point) |
| `findAndModify` | string | The collection against which to run the command. |
| `collation` | document | Optional. Optional. Specifies the [collation](https://www.mongodb.com/docs/manual/reference/collation.md#std-label-collation)  to use for the operation. [Collation](https://www.mongodb.com/docs/manual/reference/collation.md#std-label-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.](https://www.mongodb.com/docs/manual/reference/collation.md#std-label-collation-document-fields) If the collation is unspecified but the collection has a default collation (see [`db.createCollection()`](https://www.mongodb.com/docs/manual/reference/method/db.createcollection.md#mongodb-method-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>]`](https://www.mongodb.com/docs/manual/reference/operator/update/positional-filtered.md#mongodb-update-up.---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. 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 [Array Update Operations with `arrayFilters`.](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#std-label-findAndModify-command-arrayFilters) `arrayFilters` is not available for updates that use an aggregation pipeline. |
| `hint` | document or string | Optional. A document or string that specifies the [index](https://www.mongodb.com/docs/manual/indexes.md#std-label-indexes) to use to support the `query`. The option can take an index specification document or the index name string. If you specify an index that does not exist, the operation errors. For an example, see [Specify `hint` for `findAndModify` Operations.](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#std-label-ex-findAndModify-hint) |
| `comment` | any | Optional. A user-provided comment to attach to this command. Once set, this comment appears alongside records of this command in the following locations: [mongod log messages](https://www.mongodb.com/docs/manual/reference/log-messages.md#std-label-log-messages-ref), in the `attr.command.cursor.comment` field.; [Database profiler](https://www.mongodb.com/docs/manual/reference/database-profiler.md#std-label-profiler) output, in the [`command.comment`](https://www.mongodb.com/docs/manual/reference/database-profiler.md#mongodb-data-system.profile.command) field.; [`currentOp`](https://www.mongodb.com/docs/manual/reference/command/currentop.md#mongodb-dbcommand-dbcmd.currentOp) output, in the [`command.comment`](https://www.mongodb.com/docs/manual/reference/command/currentop.md#mongodb-data-currentOp.command) field. A comment can be any valid [BSON type](https://www.mongodb.com/docs/manual/reference/bson-types.md#std-label-bson-types) (string, integer, object, array, etc). |
| [let](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#std-label-findAndModify-let-syntax) | 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`. To use a variable to filter results, you must access the variable within the [`$expr`](https://www.mongodb.com/docs/manual/reference/operator/query/expr.md#mongodb-query-op.-expr) operator. For a complete example using `let` and variables, see [Use Variables in `let`.](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#std-label-findAndModify-let-example) **New in version 5.0** |

## Output

The [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) command returns a document with the following fields:

| Field | Type | Description |
| --- | --- | --- |
| `value` | document | Contains the command's returned value. See [`value`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#std-label-findandmodify-value-field) for details. |
| `lastErrorObject` | document | Contains information about updated documents. See [`lastErrorObject`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#std-label-findandmodify-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 |
| --- | --- | --- |
| `n` | integer | Contains the number of documents that matched the update predicate or the number of documents that the command inserted or deleted. |
| `updatedExisting` | boolean | Contains `true` if an `update` operation: Updated an existing document.; Found the document, but it was already in the desired destination state so no update actually occurred. |
| `upserted` | document | Contains the [ObjectId](https://www.mongodb.com/docs/manual/reference/bson-types.md#std-label-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 is `false`:

  - the pre-modification document if the query matches a document;

  - otherwise, `null`.

- If `new` is `true`:

  - the updated document if the query returns a match;

  - the inserted document if `upsert: true` and no document matches the query;

  - otherwise, `null`.

## Behavior

### Upsert with Unique Index

Upserts can create duplicate documents, unless there is a [unique index](https://www.mongodb.com/docs/manual/core/index-unique.md#std-label-index-type-unique) to prevent duplicates.

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

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

If all [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) operations finish the query phase before any client successfully inserts data, **and** there is no unique index on the `name` field, each [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) operation may result in an insert, creating multiple documents with `name: Andy`.

A unique index on the `name` field ensures that only one document is created. With a unique index in place, the multiple [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) operations now exhibit the following behavior:

- Exactly one [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) operation will successfully insert a new document.

- Other [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) operations either update the newly-inserted document or fail due to a unique key collision.

  In order for other [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) operations to update the newly-inserted document, **all** of the following conditions must be met:

  - The target collection has a unique index that would cause a duplicate key error.

  - The update operation is not `updateMany` or `multi` is `false`.

  - The update match condition is either:

    - A single equality predicate. For example `{ "fieldA" : "valueA" }`

    - A logical AND of equality predicates. For example `{ "fieldA" :
      "valueA", "fieldB" : "valueB" }`

  - The fields in the equality predicate match the fields in the unique index key pattern.

  - The update operation does not modify any fields in the unique index key pattern.

The following table shows examples of `upsert` operations that, when a key collision occurs, either result in an update or fail.

| Unique Index Key Pattern | Update Operation | Result |
| --- | --- | --- |
| `{ name : 1 }` | `db.people.updateOne(
   { name: "Andy" },
   { $inc: { score: 1 } },
   { upsert: true }
)` | The `score` field of the matched document is incremented by 1. |
| `{ name : 1 }` | `db.people.updateOne(
   { name: { $ne: "Joe" } },
   { $set: { name: "Andy" } },
   { upsert: true }
 )` | The operation fails because it modifies the field in the unique index key pattern (`name`). |
| `{ name : 1 }` | `db.people.updateOne(
  { name: "Andy", email: "andy@xyz.com" },
  { $set: { active: false } },
  { upsert: true }
)` | The operation fails because the equality predicate fields (`name`, `email`) do not match the index key field (`name`). |

### Sharded Collections

To use [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) on a sharded collection:

- If you only target one shard, you can use a partial shard key in the `query` field or,

- You can provide an equality condition on a full shard key in the `query` field.

- Starting in version 7.1, you do not need to provide the [shard key](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-shard-key) or `_id` field in the query specification.

Documents in a sharded collection can be [missing the shard key fields](https://www.mongodb.com/docs/manual/core/sharding-shard-key.md#std-label-shard-key-missing). 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:

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

#### Shard Key Modification

You can update a document's shard key value unless the shard key field is the immutable `_id` field.

**Warning:**

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 update the **existing** shard key value with [`findAndModify`:](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify)

- You must run on a [`mongos`](https://www.mongodb.com/docs/manual/reference/program/mongos.md#mongodb-binary-bin.mongos). Do not run the operation directly on the shard.

- You must run either in a [transaction](https://www.mongodb.com/docs/manual/core/transactions.md#std-label-transactions) or as a [retryable write.](https://www.mongodb.com/docs/manual/core/retryable-writes.md#std-label-retryable-writes)

- You must include an equality filter on the full shard key.

#### Missing Shard Key

Documents in a sharded collection can be [missing the shard key fields](https://www.mongodb.com/docs/manual/core/sharding-shard-key.md#std-label-shard-key-missing). To use [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) to set the document's **missing** shard key:

- You must run on a [`mongos`](https://www.mongodb.com/docs/manual/reference/program/mongos.md#mongodb-binary-bin.mongos). Do not run the operation directly on the shard.

- You must run either in a [transaction](https://www.mongodb.com/docs/manual/core/transactions.md#std-label-transactions) or as a [retryable write](https://www.mongodb.com/docs/manual/core/retryable-writes.md#std-label-retryable-writes) 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.

See also:

- [Set Missing Shard Key Fields](https://www.mongodb.com/docs/manual/core/sharding-shard-key.md#std-label-shard-key-missing)

### Schema Validation

The [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) command adds support for the `bypassDocumentValidation` option, which lets you bypass [schema validation](https://www.mongodb.com/docs/manual/core/schema-validation.md#std-label-schema-validation-overview) when inserting or updating documents in a collection with validation rules.

### Comparisons with the `update` Method

When updating a document, [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) and the [`updateOne()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.updateone.md#mongodb-method-db.collection.updateOne) method operate differently:

- If multiple documents match the update criteria, for [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify), you can specify a `sort` to provide some measure of control on which document to update.

  [`updateOne()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.updateone.md#mongodb-method-db.collection.updateOne) updates the first document that matches.

- By default, [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) returns an object that contains the pre-modified version of the
  document, as well as the status of the operation. To obtain the updated document, use the `new` option.

  The [`updateOne()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.updateone.md#mongodb-method-db.collection.updateOne) method returns a [`WriteResult()`](https://www.mongodb.com/docs/manual/reference/method/writeresult.md#mongodb-method-WriteResult) object that contains the status of the operation.

  To return the updated document, use the [`find()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.find.md#mongodb-method-db.collection.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 [`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) and the [`updateOne()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.updateone.md#mongodb-method-db.collection.updateOne) method *atomically* update the document. See [Atomicity and Transactions](https://www.mongodb.com/docs/manual/core/write-operations-atomicity.md) for more details about interactions and order of operations of these methods.

**See also:**

[Considerations for field names](https://www.mongodb.com/docs/manual/core/dot-dollar-considerations.md#std-label-crud-concepts-dot-dollar-considerations)

### Transactions

[`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) can be used inside [distributed transactions.](https://www.mongodb.com/docs/manual/core/transactions.md#std-label-transactions)

**Important:**

In most cases, a distributed transaction incurs a greater performance cost over single document writes, and the availability of distributed transactions should not be a replacement for effective schema design. For many scenarios, the [denormalized data model (embedded documents and arrays)](https://www.mongodb.com/docs/manual/data-modeling/embedding.md#std-label-data-modeling-embedding) 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 distributed transactions.

For additional transactions usage considerations (such as runtime limit and oplog size limit), see also [Production Considerations.](https://www.mongodb.com/docs/manual/core/transactions-production-consideration.md#std-label-production-considerations)

#### Upsert within Transactions

You can create collections and indexes inside a [distributed transaction](https://www.mongodb.com/docs/manual/core/transactions.md#std-label-transactions-create-collections-indexes) if the transaction is not a cross-shard write transaction.

[`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.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.

**See also:**

[Create Collections and Indexes in a Transaction](https://www.mongodb.com/docs/manual/core/transactions.md#std-label-transactions-create-collections-indexes)

#### Write Concerns and Transactions

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.](https://www.mongodb.com/docs/manual/core/transactions.md#std-label-transactions-write-concern)

#### Write Concern Errors

If a `findAndModify` operation fails because the write concern wasn't fulfilled, the operation returns a [`writeConcernError`](https://www.mongodb.com/docs/manual/reference/method/bulkwriteresult.md#mongodb-data-writeConcernError) document.

## Examples

### Update and Return

The following command updates an existing document in the `people` collection where the document matches the `query` criteria:

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

This command performs the following actions:

1. 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`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/gt.md#mongodb-expression-exp.-gt) 10.

2. The `sort` orders the results of the query in ascending order. If multiple documents match the `query` condition, the command modifies the first document in sort order.

3. The `update` [`increments`](https://www.mongodb.com/docs/manual/reference/operator/update/inc.md#mongodb-update-up.-inc) the value of the `score` field by 1.

4. The command returns a document with the following fields:

   - The `lastErrorObject` field that contains the details of the command, including the field `updatedExisting` which is `true`, and

   - The `value` field that contains the original pre-modification document selected for this update:

     ```javascript
     {
       "lastErrorObject" : {
          "connectionId" : 1,
          "updatedExisting" : true,
          "n" : 1,
          "syncMillis" : 0,
          "writtenTo" : null,
          "err" : null,
          "ok" : 1
       },
       value" : {
         "_id" : ObjectId("54f62d2885e4be1f982b9c9c"),
         "name" : "Tom",
         "state" : "active",
         "rating" : 100,
         "score" : 5
       },
       "ok" : 1
     }
     ```

To return the updated document in the `value` field, add the `new:true` option to the command.

If no document match the `query` condition, the command returns a document that contains `null` in the `value` field:

```javascript
{ "value" : null, "ok" : 1 }
```

[`mongosh`](https://www.mongodb.com/docs/mongodb-shell.md#mongodb-binary-bin.mongosh) and many [drivers](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-driver) provide a [`findAndModify()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.findandmodify.md#mongodb-method-db.collection.findAndModify) helper method. Using the shell helper, this previous operation can take the following form:

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

However, the [`findAndModify()`](https://www.mongodb.com/docs/manual/reference/method/db.collection.findandmodify.md#mongodb-method-db.collection.findAndModify) shell helper method returns only the unmodified document, or if `new` is `true`, the updated document.

```javascript
{
   "_id" : ObjectId("54f62d2885e4be1f982b9c9c"),
   "name" : "Tom",
   "state" : "active",
   "rating" : 100,
   "score" : 5
}
```

### `upsert: true`

The following command uses `upsert: true` to update a matching document or insert a new one if no match exists:

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

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

If the command does **not** find a matching document, the `update` with [upsert: true](https://www.mongodb.com/docs/manual/reference/glossary.md#std-term-upsert) operation results in an insertion and returns a document with the following fields:

- The `lastErrorObject` field that contains the details of the command, including the field `upserted` that contains the `_id` value of the newly inserted document, and

- The `value` field containing `null`.

```bash
{
  "value" : null,
  "lastErrorObject" : {
     "updatedExisting" : false,
     "n" : 1,
     "upserted" : ObjectId("54f62c8bc85d4472eadea26f")
  },
  "ok" : 1
}
```

### Return New Document

The following command uses both `upsert: true` and `new: true` to update a matching document or insert a new one, and returns the new or updated document in the `value` field.

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

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

The command returns the newly inserted document in the `value` field:

```bash
{
  "lastErrorObject" : {
     "connectionId" : 1,
     "updatedExisting" : false,
     "upserted" : ObjectId("54f62bbfc85d4472eadea26d"),
     "n" : 1,
     "syncMillis" : 0,
     "writtenTo" : null,
     "err" : null,
     "ok" : 1
  },
  "value" : {
     "_id" : ObjectId("54f62bbfc85d4472eadea26d"),
     "name" : "Pascal",
     "rating" : 25,
     "state" : "active",
     "score" : 1
  },
  "ok" : 1
}
```

### 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:

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

The command returns the deleted document:

```bash
{
  "lastErrorObject" : {
     "connectionId" : 1,
     "n" : 1,
     "syncMillis" : 0,
     "writtenTo" : null,
     "err" : null,
     "ok" : 1
  },
  "value" : {
     "_id" : ObjectId("54f62a6785e4be1f982b9c9b"),
     "name" : "XYZ123",
     "score" : 1,
     "state" : "active",
     "rating" : 3
  },
  "ok" : 1
}
```

### Specify Collation

[Collation](https://www.mongodb.com/docs/manual/reference/collation.md#std-label-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:

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

The following operation includes the [collation](https://www.mongodb.com/docs/manual/reference/collation.md#std-label-collation) option:

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

The operation returns the following document:

```javascript
{
   "lastErrorObject" : {
      "updatedExisting" : true,
      "n" : 1
   },
   "value" : {
      "_id" : 1,
      "category" : "café",
      "status" : "A"
   },
   "ok" : 1
}
```

### Array Update Operations with `arrayFilters`

**Note:**

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

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:

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

To update all elements that are greater than or equal to `100` in the `grades` array, use the positional [`$[<identifier>]`](https://www.mongodb.com/docs/manual/reference/operator/update/positional-filtered.md#mongodb-update-up.---identifier--) operator with the `arrayFilters` option:

```javascript
db.runCommand(
   {
     findAndModify: "students",
     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:

```javascript
{ "_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:

```javascript
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>]`](https://www.mongodb.com/docs/manual/reference/operator/update/positional-filtered.md#mongodb-update-up.---identifier--) with the `arrayFilters` to update the `mean` for all elements in the `grades` array where the grade is greater than or equal to `85`.

```javascript
db.runCommand(
   {
     findAndModify: "students2",
     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:

```javascript
{
   "_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

[`findAndModify`](https://www.mongodb.com/docs/manual/reference/command/findandmodify.md#mongodb-dbcommand-dbcmd.findAndModify) can accept an aggregation pipeline for the update. The pipeline can consist of the following stages:

- [`$addFields`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/addfields.md#mongodb-pipeline-pipe.-addFields) and its alias [`$set`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/set.md#mongodb-pipeline-pipe.-set)

- [`$project`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/project.md#mongodb-pipeline-pipe.-project) and its alias [`$unset`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/unset.md#mongodb-pipeline-pipe.-unset)

- [`$replaceRoot`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/replaceroot.md#mongodb-pipeline-pipe.-replaceRoot) and its alias [`$replaceWith`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/replacewith.md#mongodb-pipeline-pipe.-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.

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

```javascript
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:

```javascript
db.runCommand(
   {
     findAndModify: "students2",
     query: {  "_id" : 1 },
     update: [ { $set: { "total" : { $sum: "$grades.grade" } } } ],
     new: true
   }
)
```

**Note:**

The `$set` used in the pipeline refers to the aggregation stage [`$set`](https://www.mongodb.com/docs/manual/reference/operator/aggregation/set.md#mongodb-pipeline-pipe.-set) and not the update operator [`$set`.](https://www.mongodb.com/docs/manual/reference/operator/update/set.md#mongodb-update-up.-set)

After the operation, the collection has the following documents:

```javascript
{
  "_id" : 1,
  "grades" : [ { "grade" : 80, "mean" : 75, "std" : 6 }, { "grade" : 85, "mean" : 90, "std" : 4 }, { "grade" : 85, "mean" :85, "std" : 6 } ],
  "total" : 250
}
{
   "_id" : 2,
   "grades" : [ { "grade" : 90, "mean" : 75, "std" : 6 }, { "grade" : 87, "mean" : 90, "std" : 3 }, { "grade" : 85, "mean" : 85,"std" : 4 } ]
}
```

### Specify `hint` for `findAndModify` Operations

In [`mongosh`](https://www.mongodb.com/docs/mongodb-shell.md#mongodb-binary-bin.mongosh), create a `members` collection with the following documents:

```javascript
db.members.insertMany( [
   { "_id" : 1, "member" : "abc123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 2, "member" : "xyz123", "status" : "A", "points" : 60,  "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment" },
   { "_id" : 3, "member" : "lmn123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 4, "member" : "pqr123", "status" : "D", "points" : 20,  "misc1" : "Deactivated", "misc2" : null },
   { "_id" : 5, "member" : "ijk123", "status" : "P", "points" :  0,  "misc1" : null, "misc2" : null },
   { "_id" : 6, "member" : "cde123", "status" : "A", "points" : 86,  "misc1" : "reminder: ping me at 100pts", "misc2" : "Some random comment" }
] )
```

Create the following indexes on the collection:

```javascript
db.members.createIndex( { status: 1 } )
db.members.createIndex( { points: 1 } )
```

The following operation explicitly hints to use the index `{ status: 1 }`:

```javascript
db.runCommand({
   findAndModify: "members",
   query: { "points": { $lte: 20 }, "status": "P" },
   remove: true,
   hint: { status: 1 }
})
```

**Note:**

If you specify an index that does not exist, the operation errors.

To see the index used, run [`explain`](https://www.mongodb.com/docs/manual/reference/command/explain.md#mongodb-dbcommand-dbcmd.explain) on the operation:

```javascript
db.runCommand(
   {
     explain: {
       findAndModify: "members",
       query: { "points": { $lte: 20 }, "status": "P" },
       remove: true,
       hint: { status: 1 }
     },
     verbosity: "queryPlanner"
   }
)
```

### Use Variables in `let`

**New in version 5.0**

To define variables that you can access elsewhere in the command, use the [let](https://www.mongodb.com/docs/manual/reference/method/db.collection.updateone.md#std-label-updateOne-let-syntax) option.

**Note:**

To filter results using a variable, you must access the variable within the [`$expr`](https://www.mongodb.com/docs/manual/reference/operator/query/expr.md#mongodb-query-op.-expr) operator.

Create a collection `cakeFlavors`:

```javascript
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:

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