$addToSet
Reference group: Array update operators
What it does
Adds a value only if an equal value is not already present.
Syntax
{$addToSet: { array: value }}
Use case
Maintain set-like roles/tags.
$addToSet: practical example
db.users.updateOne({ _id: userId }, { $addToSet: { roles: "editor" } })💡 Explanation
Adds a value only if an equal value is not already present.
When to use it
Maintain set-like roles/tags.
Key Takeaways
- Adds a value only if an equal value is not already present.
- Typical use: Maintain set-like roles/tags.