The $allElementsTrue operator checks whether every element in an array evaluates to true. It is ideal for validation checklists, permission flags, test results, and any “all must pass” logic inside aggregation pipelines.
Verify every element passes.
Pass one array expression.
Works on true/false values.
Build conditions per item.
QA, permissions, validation.
Empty array returns true.
In MongoDB’s aggregation framework, the $allElementsTrue operator evaluates an array and returns true if no element is false. For example, [true, true, true] returns true, but [true, false, true] returns false. This is useful when you store boolean flags or pass/fail results as arrays in documents.
Pair $allElementsTrue with $map when you need to test a condition on each item in an array (for example, “every score is at least 60”).
The $allElementsTrue operator takes one array expression wrapped in an array:
{ $allElementsTrue: [ <array expression> ] }$allElementsTrue — returns true when no element in the array is false."$flags" or a $map result).true.$project, $addFields, $match (with $expr), or $set.These two operators are often confused. Here is the difference:
[true, false] → allElementsTrue: false, anyElementTrue: true| Question | Answer |
|---|---|
| Operator type | Aggregation expression operator (boolean / array) |
| Syntax | { $allElementsTrue: [ <array> ] } |
| Input | Array of boolean values (or boolean-like values) |
| Empty array | Returns true |
| Since | MongoDB 5.0 |
[
true,
true
]Returns true
[
true,
false
]Returns false
[]Returns true
{
$allElementsTrue: ["$flags"]
}From document array
Check boolean arrays, validate checklists, and combine $allElementsTrue with $map for custom conditions.
Start with a collection that stores boolean arrays and test whether all flags are true.
Suppose you have a checks collection with a flags array on each document:
[
{ "_id": 1, "label": "Deployment A", "flags": [ true, true, true ] },
{ "_id": 2, "label": "Deployment B", "flags": [ true, false, true ] },
{ "_id": 3, "label": "Deployment C", "flags": [] }
]Check whether every flag in the array is true:
db.checks.aggregate([
{
$project: {
label: 1,
flags: 1,
allPassed: { $allElementsTrue: [ "$flags" ] }
}
}
])true → returns true.false → returns false.true (no false elements).Filter passing records, validate checklists, and evaluate custom conditions with $map.
Use $match with $expr to return only fully validated records:
db.checks.aggregate([
{
$match: {
$expr: { $allElementsTrue: [ "$flags" ] }
}
},
{
$project: {
label: 1,
status: "approved"
}
}
])Deployment B is excluded because one flag is false. This pattern is common in QA pipelines where only fully passing records should proceed.
Check whether every score in an array is at least 60:
db.students.aggregate([
{
$project: {
name: 1,
scores: 1,
allPassing: {
$allElementsTrue: [
{
$map: {
input: "$scores",
as: "score",
in: { $gte: [ "$$score", 60 ] }
}
}
]
}
}
}
])$map converts each score into a boolean (true if ≥ 60). Then $allElementsTrue checks whether every mapped result is true.
Verify that a user has all required permissions enabled:
db.users.aggregate([
{
$addFields: {
requiredPerms: [ "$canRead", "$canWrite", "$canDelete" ]
}
},
{
$project: {
username: 1,
hasFullAccess: {
$allElementsTrue: [ "$requiredPerms" ]
}
}
}
])Build a temporary boolean array from individual permission fields, then test whether every permission is true. Users missing any permission get false.
$map.$allElementsTrue WorksThe pipeline evaluates the array expression — a field like "$flags" or a $map result.
MongoDB checks every element. If any element is false, the operator stops and returns false.
If no false elements exist (including empty arrays), the result is true.
Use the boolean in $match, $cond, or projected status fields.
The $allElementsTrue operator is a clean way to express “every item must pass” logic in MongoDB aggregation pipelines. It works directly on boolean arrays and pairs naturally with $map when you need custom per-element conditions.
For beginners, remember: one false fails the check, an empty array passes, and you need MongoDB 5.0 or later.
$map when elements are not already booleans$match and $expr to filter passing records$anyElementTrue when you need “at least one” logic$allElementsTrue with $and (different purpose)false value fails the entire check$allElementsTrueUse these points when validating arrays in aggregation pipelines.
No false elements allowed.
Purpose{ $allElementsTrue: [arr] }
Custom per-item tests.
PatternReturns true.
Edge caseRequires modern version.
VersionMove on to $and for combining multiple boolean expressions.
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