The $anyElementTrue operator checks whether at least one element in an array evaluates to true. It is ideal for “any item passes” logic — such as finding records with at least one enabled permission, one passing test, or one active flag.
At least one must pass.
Pass one array expression.
Works on true/false values.
Build conditions per item.
Alerts, permissions, QA.
Empty array returns false.
In MongoDB’s aggregation framework, the $anyElementTrue operator evaluates an array and returns true if at least one element is true. For example, [false, true, false] returns true, but [false, false] returns false. This is the opposite strictness of $allElementsTrue, which requires every element to pass.
Pair $anyElementTrue with $map when you need to test a custom condition on each array item (for example, “at least one score is above 90”).
The $anyElementTrue operator takes one array expression wrapped in an array:
{ $anyElementTrue: [ <array expression> ] }$anyElementTrue — returns true when at least one element is true."$flags" or a $map result).false.$project, $addFields, $match (with $expr), or $set.These operators are often used together. Here is the difference:
[true, false] → anyElementTrue: true, allElementsTrue: false[] → anyElementTrue: false, allElementsTrue: true| Question | Answer |
|---|---|
| Operator type | Aggregation expression operator (boolean / array) |
| Syntax | { $anyElementTrue: [ <array> ] } |
| Input | Array of boolean values (or boolean-like values) |
| Empty array | Returns false |
| Since | MongoDB 5.0 |
[
false,
true
]Returns true
[
false,
false
]Returns false
[]Returns false
{
$anyElementTrue: ["$flags"]
}From document array
Check boolean arrays, filter records with at least one passing flag, and combine $anyElementTrue with $map.
Test whether at least one flag in an array is true using $project.
Suppose you have a checks collection with a flags array on each document:
[
{ "_id": 1, "label": "Service A", "flags": [ false, true, false ] },
{ "_id": 2, "label": "Service B", "flags": [ false, false, false ] },
{ "_id": 3, "label": "Service C", "flags": [] }
]Check whether at least one flag is true:
db.checks.aggregate([
{
$project: {
label: 1,
flags: 1,
hasAnyPass: { $anyElementTrue: [ "$flags" ] }
}
}
])true → returns true.false → returns false.false (no true elements).Filter documents, detect high scores, and check permission arrays.
Return only records where at least one flag is true:
db.checks.aggregate([
{
$match: {
$expr: { $anyElementTrue: [ "$flags" ] }
}
},
{
$project: {
label: 1,
status: "has passing check"
}
}
])Only Service A has at least one true flag. Services B and C are filtered out.
Check whether at least one score is 90 or above:
db.students.aggregate([
{
$project: {
name: 1,
scores: 1,
hasHighScore: {
$anyElementTrue: [
{
$map: {
input: "$scores",
as: "score",
in: { $gte: [ "$$score", 90 ] }
}
}
]
}
}
}
])$map converts each score into a boolean (true if ≥ 90). Then $anyElementTrue checks whether at least one mapped result is true.
Detect users who have any access permission turned on:
db.users.aggregate([
{
$addFields: {
permissions: [ "$canRead", "$canWrite", "$canDelete" ]
}
},
{
$project: {
username: 1,
hasAnyAccess: {
$anyElementTrue: [ "$permissions" ]
}
}
}
])Build a boolean array from permission fields. If at least one is true, the user has some level of access. All-false arrays return false.
$map.$anyElementTrue WorksThe pipeline evaluates the array expression — a field like "$flags" or a $map result.
MongoDB checks each element. The first true value is enough to return true.
If no true elements exist (including empty arrays), the result is false.
Use the boolean in $match, $cond, or projected status fields.
The $anyElementTrue operator is the right choice for “at least one item passes” logic in MongoDB aggregation pipelines. It complements $allElementsTrue and pairs naturally with $map for custom per-element conditions.
For beginners, remember: one true is enough, an empty array returns false, and you need MongoDB 5.0 or later.
$map when elements are not already booleans$match and $expr to filter matching records$allElementsTrue when you need strict “all pass” logic$anyElementTrue with $or (different purpose)$allElementsTrue behavior)$anyElementTrueUse these points when validating arrays in aggregation pipelines.
One true is enough.
Purpose{ $anyElementTrue: [arr] }
Custom per-item tests.
PatternReturns false.
Edge caseRequires modern version.
VersionMove on to $arrayElemAt or review $allElementsTrue for strict all-pass checks.
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