$mergeObjects

Reference type:Cheat sheetFormat:Syntax + example + use case

Reference group: Object and set expressions

What it does

Merges objects; later values override earlier duplicate keys.

Syntax

{$mergeObjects: [objects...]} 

Use case

Apply defaults and overrides.

$mergeObjects: practical example
{ $project: { settings: { $mergeObjects: [{ theme: "light" }, "$preferences"] } } }
💡 Explanation Merges objects; later values override earlier duplicate keys. When to use it Apply defaults and overrides.
Key Takeaways
  • Merges objects; later values override earlier duplicate keys.
  • Typical use: Apply defaults and overrides.