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db.collection.findOneAndReplace()

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Definition

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

New in version 3.2.

Modifies and replaces a single document based on the filter and sort criteria.

The findOneAndReplace() method has the following form:

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

The findOneAndReplace() method takes the following parameters:

Parameter Type Description
filter document

The selection criteria for the update. The same query selectors as in the find() method are available.

Specify an empty document { } to replace the first document returned in the collection.

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 parameter.

sort document

Optional. Specifies a sorting order for the documents matched by the filter.

See cursor.sort().

maxTimeMS number Optional. Specifies a time limit in milliseconds within which the operation must complete. Throws 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.

returnNewDocument boolean

Optional. When true, returns the replacement document instead of the original document.

Defaults to false.

Returns:Returns either the original document or, if returnNewDocument: true, the replacement document.

Behavior

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

The projection parameter takes a document in the following form:

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

The <boolean> value can be any of the following:

  • 1 or true to include the field. The method returns the _id field even if it is not explicitly stated in the projection parameter.
  • 0 or false to exclude the field. This can be used on any field, including _id.

Examples

Replace A Document

The scores collection contains documents similar to the following:

{ "_id" : 1521, "team" : "Fearful Mallards", "score" : 25000 },
{ "_id" : 2231, "team" : "Tactful Mooses", "score" : 23500 },
{ "_id" : 4511, "team" : "Aquatic Ponies", "score" : 19250 },
{ "_id" : 5331, "team" : "Cuddly Zebras", "score" : 15235 },
{ "_id" : 3412, "team" : "Garrulous Bears", "score" : 22300 }

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

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

The operation returns the original document that has been replaced:

{ "_id" : 2512, "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

The scores collection contains documents similar to the following:

{ "_id" : 1521, "team" : "Fearful Mallards", "score" : 25000 },
{ "_id" : 2231, "team" : "Tactful Mooses", "score" : 23500 },
{ "_id" : 4511, "team" : "Aquatic Ponies", "score" : 19250 },
{ "_id" : 5331, "team" : "Cuddly Zebras", "score" : 15235 },
{ "_id" : 3412, "team" : "Garrulous Bears", "score" : 22300 }

By including ascending sort order on the score field, the following example replaces the document with lowest score among the matching documents:

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

The operation returns the original document that has been replaced:

{ "_id" : 5112, "team" : "Cuddly Zebras", "score" : 15235 }

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

Project Specific Fields in Return Document

The scores collection contains documents similar to the following:

{ "_id" : 1521, "team" : "Fearful Mallards", "score" : 25000 },
{ "_id" : 2231, "team" : "Tactful Mooses", "score" : 23500 },
{ "_id" : 4511, "team" : "Aquatic Ponies", "score" : 19250 },
{ "_id" : 5331, "team" : "Cuddly Zebras", "score" : 15235 },
{ "_id" : 3412, "team" : "Garrulous Bears", "score" : 22300 }

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

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:

{ "team" : "Cuddly Zebras" }

Replace Document with Time Limit

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

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:

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 nothing matches the filter:

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

The operation returns the following:

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

If returnNewDocument was false, the operation would return null as there is no original document to return.