db.collection.findOneAndReplace()¶

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Definition
Syntax
Behavior
Examples

Definition¶

db.collection.findOneAndReplace(filter, replacement, options)¶

Important

mongosh Method

This page documents a mongosh method. This is not the documentation for a language-specific driver such as Node.js.

For MongoDB API drivers, refer to the language-specific :driver:`MongoDB driver documentation </>`.

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

:v4.4:`mongo shell v4.4 </mongo>`
mongo shell v4.2

Replaces a single document based on the specified filter.

Syntax¶

The findOneAndReplace() method has the following form:

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db.collection.findOneAndReplace(
   <filter>,
   <replacement>,
   {
     projection: <document>,
     sort: <document>,
     maxTimeMS: <number>,
     upsert: <boolean>,
     returnDocument: <string>,
     returnNewDocument: <boolean>,
     collation: <document>
   }
)

Fields and Options¶

The findOneAndReplace() method takes the following fields and options:

Field	Type	Description
filter	document	The selection criteria for the update. The same query selectors as in the `find()` method are available. To replace the first document returned in the collection, specify an empty document `{ }`. If unspecified, defaults to an empty document. Starting in MongoDB 4.2, the operation returns an error if the query argument is not a document.
replacement	document	The replacement document. Cannot contain update operators. The `<replacement>` document cannot specify an `_id` value that differs from the replaced document.
projection	document	Optional. A subset of fields to return. To return all fields in the matching document, omit this field. Starting in MongoDB 4.2, the operation returns an error if the projection field is not a document.
sort	document	Optional. Specifies a sorting order for the documents matched by the filter. Starting in MongoDB 4.2, the operation returns an error if the sort field is not a document. See `cursor.sort()`.
`maxTimeMS`	number	Optional. Specifies a time limit in milliseconds within which the operation must complete. Returns an error if the limit is exceeded.
upsert	boolean	Optional. When `true`, `findOneAndReplace()` either: Inserts the document from the `replacement` parameter if no document matches the `filter`. Returns `null` after inserting the new document, unless `returnNewDocument` is `true`. Replaces the document that matches the `filter` with the `replacement` document. MongoDB will add the `_id` field to the replacement document if it is not specified in either the `filter` or `replacement` documents. If `_id` is present in both, the values must be equal. To avoid multiple upserts, ensure that the `query` fields are uniquely indexed. Defaults to `false`.
returnDocument	string	Optional. Starting in `mongosh` 0.13.2, `returnDocument` is an alternative for returnNewDocument. If both options are set, `returnDocument` takes precedence. `returnDocument: "before"` returns the original document. `returnDocument: "after"` returns the updated document.
returnNewDocument	boolean	Optional. When `true`, returns the replacement document instead of the original document. Defaults to `false`.
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: copy 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.

Returns¶

Returns the original document by default. Returns the updated document if returnDocument is set to after or returnNewDocument is set to true.

Behavior¶

Document Match¶

db.collection.findOneAndReplace() replaces the first matching document in the collection that matches the filter. The sort field can be used to influence which document is modified.

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 projection field takes a document in the following form:

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

Projection	Description
`<field>: <1 or true>`	Specifies the inclusion of a field. Non-zero integers are also treated as `true`.
`<field>: <0 or false>`	Specifies the exclusion of a field.
`"<field>.$": <1 or true>`	With the use of the `$` array projection operator, you can specify the projection to return the first element that match the query condition on the array field; e.g. `"arrayField.$" : 1`. (Not available for views.) Non-zero integers are also treated as `true`.
`<field>: <array projection>`	Using the array projection operators `$elemMatch`, `$slice`, specifies the array element(s) to include, thereby excluding those elements that do not meet the expressions. (Not available for views.)
`<field>: <aggregation expression>`	Specifies the value of the projected field. Starting in MongoDB 4.4, with the use of aggregation expressions and syntax, including the use of literals and aggregation variables, you can project new fields or project existing fields with new values. For example, If you specify a non-numeric, non-boolean literal (such as a literal string or an array or an operator expression) for the projection value, the field is projected with the new value; e.g.: `{ field: [ 1, 2, 3, "$someExistingField" ] }` `{ field: "New String Value" }` `{ field: { status: "Active", total: { $sum: "$existingArray" } } }` To project a literal value for a field, use the `$literal` aggregation expression; e.g.: `{ 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; e.g. "field.nestedfield": <value>
nested form; e.g. { 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

Sharded Collections¶

To use db.collection.findOneAndReplace() on a sharded collection, the query filter :red:`must` include an equality condition on the 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 :red:`in conjunction with` another filter condition (such as on the _id field). For example:

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{ _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.findOneAndReplace():

You :red:`must` run on a mongos. Do :red:`not` issue the operation directly on the shard.
You :red:`must` run either in a transaction or as a retryable write.
You :red:`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.findOneAndReplace() to set the document’s missing shard key,

You :red:`must` run on a mongos. Do :red:`not` issue the operation directly on the shard.
You :red:`must` run either in a transaction or as a retryable write if the new shard key value is not null.
You :red:`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.

Transactions¶

db.collection.findOneAndReplace() 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 :red:`not` a cross-shard write transaction.

Specifically, in MongoDB 4.4 and greater, db.collection.findOneAndReplace() 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.

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.

Examples¶

Replace A Document¶

Create a sample scores collection with the following documents:

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db.scores.insertMany([
   { "_id" : 1, "team" : "Fearful Mallards", "score" : 25000 },
   { "_id" : 2, "team" : "Tactful Mooses", "score" : 23500 },
   { "_id" : 3, "team" : "Aquatic Ponies", "score" : 19250 },
   { "_id" : 4, "team" : "Cuddly Zebras", "score" : 15235 },
   { "_id" : 5, "team" : "Garrulous Bears", "score" : 18000 }
]);

The following operation finds a document with score less than 20000 and replaces it:

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db.scores.findOneAndReplace(
   { "score" : { $lt : 20000 } },
   { "team" : "Observant Badgers", "score" : 20000 }
)

The operation returns the original document that has been replaced:

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{ "_id" : 3, "team" : "Aquatic Ponies", "score" : 19250 }

If returnNewDocument was true, the operation would return the replacement document instead.

Although multiple documents meet the filter criteria, db.collection.findOneAndReplace replaces only one document.

Sort and Replace A Document¶

Create a sample scores collection with the following documents:

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db.scores.insertMany([
   { "_id" : 1, "team" : "Fearful Mallards", "score" : 25000 },
   { "_id" : 2, "team" : "Tactful Mooses", "score" : 23500 },
   { "_id" : 3, "team" : "Aquatic Ponies", "score" : 19250 },
   { "_id" : 4, "team" : "Cuddly Zebras", "score" : 15235 },
   { "_id" : 5, "team" : "Garrulous Bears", "score" : 18000 }
]);

By including an ascending sort on the score field, the following example replaces the document with the lowest score among those documents that match the filter:

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db.scores.findOneAndReplace(
   { "score" : { $lt : 20000 } },
   { "team" : "Observant Badgers", "score" : 20000 },
   { sort: { "score" : 1 } }
)

The operation returns the original document that has been replaced:

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{ "_id" : 4, "team" : "Cuddly Zebras", "score" : 15235 }

See Replace A Document for the non-sorted result of this command.

Project Specific Fields in Return Document¶

Create a sample scores collection with the following documents:

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db.scores.insertMany([
   { "_id" : 1, "team" : "Fearful Mallards", "score" : 25000 },
   { "_id" : 2, "team" : "Tactful Mooses", "score" : 23500 },
   { "_id" : 3, "team" : "Aquatic Ponies", "score" : 19250 },
   { "_id" : 4, "team" : "Cuddly Zebras", "score" : 15235 },
   { "_id" : 5, "team" : "Garrulous Bears", "score" : 18000 }
])

The following operation uses projection to only display the team field in the returned document:

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db.scores.findOneAndReplace(
   { "score" : { $lt : 22250 } },
   { "team" : "Therapeutic Hamsters", "score" : 22250 },
   { sort : { "score" : 1 }, projection: { "_id" : 0, "team" : 1 } }
)

The operation returns the original document with only the team field:

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{ "team" : "Cuddly Zebras" }

Replace Document with Time Limit¶

The following operation sets a 5ms time limit to complete:

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try {
   db.scores.findOneAndReplace(
      { "score" : { $gt : 25000 } },
      { "team" : "Emphatic Rhinos", "score" : 25010 },
      { maxTimeMS: 5 }
   );
} catch(e){
   print(e);
}

If the operation exceeds the time limit, it returns:

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Error: findAndModifyFailed failed: { "ok" : 0, "errmsg" : "operation exceeded time limit", "code" : 50 }

Replace Document with Upsert¶

The following operation uses the upsert field to insert the replacement document if no document matches the filter:

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try {
   db.scores.findOneAndReplace(
      { "team" : "Fortified Lobsters" },
      { "_id" : 6019, "team" : "Fortified Lobsters" , "score" : 32000},
      { upsert : true, returnDocument: "after" }
   );
} catch (e){
   print(e);
}

The operation returns the following:

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{
   "_id" : 6019,
   "team" : "Fortified Lobsters",
   "score" : 32000
}

If returnDocument: "before" was set, the operation would return null because there is no original document to return.

Specify Collation¶

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.

Create a sample myColl collection with the following documents:

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db.myColl.insertMany([
   { _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:

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db.myColl.findOneAndReplace(
   { category: "cafe", status: "a" },
   { category: "cafÉ", status: "Replaced" },
   { collation: { locale: "fr", strength: 1 } }
);

The operation returns the following document:

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

← db.collection.findOneAndDelete() db.collection.findOneAndUpdate() →

db.collection.findOneAndReplace()¶

Definition¶

Syntax¶

Fields and Options¶

Returns¶

Behavior¶

Document Match¶

Projection¶

Embedded Field Specification¶

_id Field Projection¶

Inclusion or Exclusion¶

Sharded Collections¶

Shard Key Modification¶

Missing Shard Key¶

Transactions¶

Upsert within Transactions¶

Write Concerns and Transactions¶

Examples¶

Replace A Document¶

Sort and Replace A Document¶

Project Specific Fields in Return Document¶

Replace Document with Time Limit¶

Replace Document with Upsert¶

Specify Collation¶

`_id` Field Projection¶