$setEquals (Check Set Equality)

Last updated: 2026-10-09

$setEquals (Check Set Equality)

$setEquals checks whether two or more arrays are equal as sets, ignoring order and duplicates. Typical uses: verifying that two permission lists match or comparing a config with defaults. It accepts multiple arguments and returns true only when all arrays are set-equal. null elements are ignored, so arrays containing null compare as if the null were absent. Order does not matter: [1, 2] and [2, 1] are equal.

📝 Syntax

{ $setEquals: [ <array1>, <array2>, ... ] }

⚙️ Parameters

Returns：true when all arrays are set-equal, otherwise false

▶ Example

Run the commands below in your local mongosh (requires a running mongod):

// $setEquals: do two permission lists match
db.roles.aggregate([
  { $project: {
      samePerms: { $setEquals: ['$userPerms', '$defaultPerms'] }
  } }
])

Output：

{ '_id': 1, 'samePerms': true }

📌 Notes

• Order and duplicates are ignored: [1, 2] equals [2, 1, 1]
• Multiple arguments are supported; all must be equal for true
• null elements are ignored, as if absent

🏷️ Related Tags

💡 Related Cases

📚 Related Tutorials

❓ FAQ

Web-Tutorial Tech Team

A team of developers maintaining programming tutorials. Each tutorial is written and reviewed by developers with expertise in that field. We work to keep our content accurate and reliable — if you spot an issue, please let us know.

About Us