$setOnInsert
Reference group: Update operator families
What it does
Applies values only when an upsert inserts a new document.
Syntax
{$setOnInsert: { field: value }}
Use case
Initialize creation metadata.
$setOnInsert: practical example
db.settings.updateOne({ _id: "theme" }, { $set: { enabled: true }, $setOnInsert: { createdAt: new Date() } }, { upsert: true })💡 Explanation
Applies values only when an upsert inserts a new document.
When to use it
Initialize creation metadata.
Key Takeaways
- Applies values only when an upsert inserts a new document.
- Typical use: Initialize creation metadata.