Add reference Markdown: operators/set-expression

reference/operators/set-expression/$allelementstrue.md

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+---
+title: $allElementsTrue
+description: The $allElementsTrue operator returns true if all elements in an array evaluate to true.
+type: operators
+category: set-expression
+---
+
+# $allElementsTrue
+
+The `$allElementsTrue` operator evaluates an array as a set. It returns `true` if no element in the array has a value of `false` or equivalent to `false` (like `null`, `0`, or `undefined`). If any element evaluates to a value of `false` or the equivalent, the operator returns `false`.
+
+## Syntax
+
+```javascript
+{
+  $allElementsTrue: [ <array> ]
+}
+```
+
+## Parameters
+
+| Parameter | Description |
+| --- | --- |
+| `array` | An array of expressions to evaluate. If the array is empty, `$allElementsTrue` returns `true`. |
+
+## Examples
+
+Consider this sample document from the stores collection.
+
+```json
+{
+    "_id": "0fcc0bf0-ed18-4ab8-b558-9848e18058f4",
+    "name": "First Up Consultants | Beverage Shop - Satterfieldmouth",
+    "location": {
+        "lat": -89.2384,
+        "lon": -46.4012
+    },
+    "staff": {
+        "totalStaff": {
+            "fullTime": 8,
+            "partTime": 20
+        }
+    },
+    "sales": {
+        "totalSales": 75670,
+        "salesByCategory": [
+            {
+                "categoryName": "Wine Accessories",
+                "totalSales": 34440
+            },
+            {
+                "categoryName": "Bitters",
+                "totalSales": 39496
+            },
+            {
+                "categoryName": "Rum",
+                "totalSales": 1734
+            }
+        ]
+    },
+    "promotionEvents": [
+        {
+            "eventName": "Unbeatable Bargain Bash",
+            "promotionalDates": {
+                "startDate": {
+                    "Year": 2024,
+                    "Month": 6,
+                    "Day": 23
+                },
+                "endDate": {
+                    "Year": 2024,
+                    "Month": 7,
+                    "Day": 2
+                }
+            },
+            "discounts": [
+                {
+                    "categoryName": "Whiskey",
+                    "discountPercentage": 7
+                },
+                {
+                    "categoryName": "Bitters",
+                    "discountPercentage": 15
+                },
+                {
+                    "categoryName": "Brandy",
+                    "discountPercentage": 8
+                },
+                {
+                    "categoryName": "Sports Drinks",
+                    "discountPercentage": 22
+                },
+                {
+                    "categoryName": "Vodka",
+                    "discountPercentage": 19
+                }
+            ]
+        },
+        {
+            "eventName": "Steal of a Deal Days",
+            "promotionalDates": {
+                "startDate": {
+                    "Year": 2024,
+                    "Month": 9,
+                    "Day": 21
+                },
+                "endDate": {
+                    "Year": 2024,
+                    "Month": 9,
+                    "Day": 29
+                }
+            },
+            "discounts": [
+                {
+                    "categoryName": "Organic Wine",
+                    "discountPercentage": 19
+                },
+                {
+                    "categoryName": "White Wine",
+                    "discountPercentage": 20
+                },
+                {
+                    "categoryName": "Sparkling Wine",
+                    "discountPercentage": 19
+                },
+                {
+                    "categoryName": "Whiskey",
+                    "discountPercentage": 17
+                },
+                {
+                    "categoryName": "Vodka",
+                    "discountPercentage": 23
+                }
+            ]
+        }
+    ]
+}
+```
+
+### Example 1: Determine if all the discount percentages are higher than zero
+
+This query determines if all the discount percentages in each promotion event are greater than zero.
+
+```javascript
+db.stores.aggregate([
+  { $match: {"_id": "2cf3f885-9962-4b67-a172-aa9039e9ae2f"} },
+  { $unwind: "$promotionEvents" },
+  {
+    $project: {
+      allDiscountsValid: {
+        $allElementsTrue: [
+          {
+            $map: {
+              input: "$promotionEvents.discounts.discountPercentage",
+              as: "discount",
+              in: { $gt: ["$$discount", 0] }
+            }
+          }
+        ]
+      }
+    }
+  }
+])
+```
+
+This query returns the following result.
+
+```json
+[
+  {
+    "_id": "2cf3f885-9962-4b67-a172-aa9039e9ae2f",
+    "allDiscountsValid": true
+  }
+]
+```