db.collection.findOneAndReplace()¶

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Definition
Behavior

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 within. Throws an error if the limit is exceeded.
`upsert`	boolean	Optional. When `true`, `findOneAndReplace()` creates a new document if no document matches the `filter`. If a document matches the filter, the method performs a replacement. The new document is created using the equality conditions from the `filter` with the `replacement` document. Comparison conditions like `$gt` or `$lt` are ignored. Returns `null` after inserting the new document, unless `returnNewDocument` is `true`. 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 the first 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.

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 }

Sorting by score changes the result of the operation. The following operation sorts the result of the filter by score ascending, and replaces the lowest scoring document:

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 the Returned 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 }, project: { "_id" : 0, "team" : 1 } }
)

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

{ "team" : "Aquatic Ponies"}

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.

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

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