$setOnInsert
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Definition
-
$setOnInsert
-
If an update operation with upsert: true results in an insert of a document, then
$setOnInsert
assigns the specified values to the fields in the document. If the update operation does not result in an insert,$setOnInsert
does nothing.You can specify the
upsert
option for either thedb.collection.update()
ordb.collection.findAndModify()
methods.To specify a
<field>
in an embedded document or in an array, use dot notation.
Example
A collection named products
contains no documents.
Then, the following db.collection.update()
with upsert: true inserts a new document.
MongoDB creates a new document with _id
equal to 1
from the <query>
condition, and then applies the $set
and $setOnInsert
operations to this document.
The products
collection contains the newly-inserted document:
If the db.collection.update()
with upsert: true had found a matching document, then MongoDB performs an update, applying the $set
operation but ignoring the $setOnInsert
operation.