Merge pull request #2989 from abinav2307/projection-third-pass-validation

Projection third pass validation

Author: JamesJBarnett

articles/cosmos-db/.openpublishing.redirection.cosmos-db.json

@@ -675,6 +675,21 @@
       "redirect_url": "/azure/cosmos-db/mongodb/vcore/operators/aggregation/$unset",
       "redirect_document_id": true
     },
+    {
+      "source_path_from_root": "/articles/cosmos-db/mongodb/vcore/operators/projection/$slice.md",
+      "redirect_url": "/azure/cosmos-db/mongodb/vcore/operators/array-expression/$slice",
+      "redirect_document_id": false
+    },
+    {
+      "source_path_from_root": "/articles/cosmos-db/mongodb/vcore/operators/projection/$elemmatch.md",
+      "redirect_url": "/azure/cosmos-db/mongodb/vcore/operators/array-query/$elemmatch",
+      "redirect_document_id": true
+    },
+    {
+      "source_path_from_root": "/articles/cosmos-db/mongodb/vcore/operators/projection/$.md",
+      "redirect_url": "/azure/cosmos-db/mongodb/vcore/operators/array-update/$",
+      "redirect_document_id": true
+    },
     {
       "source_path_from_root": "/articles/cosmos-db/nosql/troubleshoot-dot-net-sdk-request-timeout.md",
       "redirect_url": "/azure/cosmos-db/nosql/troubleshoot-dotnet-sdk-request-timeout",

articles/cosmos-db/mongodb/vcore/operators/array-expression/$slice.md

@@ -280,6 +280,116 @@ The query returns the following result.
 ]
 ```
 
+### Example 3: Fetch the first matching element from an array
+
+This query retrieves the first document from "sales.salesByCategory" array.
+
+```javascript
+db.stores.find({
+        "name": "Lakeshore Retail"
+    }, {
+        "_id": 1,
+        "name": 1,
+        "sales.salesByCategory": {
+            $slice: 1
+        }
+    } // restricts the fields to be returned
+)
+```
+
+This query returns the following result.
+
+```json
+[
+  {
+    "_id": "988d2dd1-2faa-4072-b420-b91b95cbfd60",
+    "name": "Lakeshore Retail",
+    "sales": {
+      "salesByCategory": [
+        {
+          "categoryName": "Towel Racks",
+          "totalSales": 13237
+        }
+      ]
+    }
+  }
+]
+```
+
+### Example 4: Fetch the last element from an array
+
+This query retrieves the last document from "sales.salesByCategory" array.
+
+```javascript
+db.stores.find({
+    "name": "Lakeshore Retail"
+}, {
+    "_id": 1,
+    "name": 1,
+    "sales.salesByCategory": {
+        $slice: -1
+    }
+})
+```
+
+This query returns the following result.
+
+```json
+[
+  {
+    "_id": "988d2dd1-2faa-4072-b420-b91b95cbfd60",
+    "name": "Lakeshore Retail",
+    "sales": {
+      "salesByCategory": [
+        {
+          "categoryName": "Pillow Cases",
+          "totalSales": 38833
+        }
+      ]
+    }
+  }
+]
+```
+
+### Example 5: Retrieve a range of elements from an array
+
+This query retrieves a subset range from "sales.salesByCategory" array.
+
+```javascript
+db.stores.find({
+    "name": "Lakeshore Retail"
+}, {
+    "_id": 1,
+    "name": 1,
+    "sales.salesByCategory": {
+        $slice: [3, 2]
+    }
+})
+```
+
+This query returns the following result.
+
+```json
+[
+  {
+    "_id": "988d2dd1-2faa-4072-b420-b91b95cbfd60",
+    "name": "Lakeshore Retail",
+    "sales": {
+      "salesByCategory": [
+        {
+          "categoryName": "Toothbrush Holders",
+          "totalSales": 47912
+        },
+        {
+          "categoryName": "Hybrid Mattresses",
+          "totalSales": 48660
+        }
+      ]
+    }
+  }
+]
+```
+
 ## Related content
 
 [!INCLUDE[Related content](../includes/related-content.md)]

articles/cosmos-db/mongodb/vcore/operators/array-update/$.md

@@ -72,7 +72,57 @@ Consider this sample document from the stores collection.
 }
 ```
 
-### Example 1: Update discount percentage for a specific category
+### Example 1: Project the first element of an array, matching the condition
+
+This query returns the first element within the `salesByCategory` array, for `DJ` equipment with `totalSales` greater than 35000.
+
+```javascript
+db.stores.find({
+    "sales.salesByCategory": {
+        $elemMatch: {
+            "categoryName": {
+                $regex: "^DJ"
+            }
+        }
+    },
+    "sales.salesByCategory.totalSales": {
+        $gt: 35000
+    }
+}, {
+    "sales.salesByCategory.$": 1
+}).limit(2)
+```
+
+The first two results returned by this query are:
+
+```json
+[
+  {
+    "_id": "d3c9df51-41bd-4b4e-a26b-b038d9cf8b45",
+    "sales": {
+      "salesByCategory": [
+        {
+          "categoryName": "DJ Speakers",
+          "totalSales": 36972
+        }
+      ]
+    }
+  },
+  {
+    "_id": "7954bd5c-9ac2-4c10-bb7a-2b79bd0963c5",
+    "sales": {
+      "salesByCategory": [
+        {
+          "categoryName": "DJ Headphones",
+          "totalSales": 35911
+        }
+      ]
+    }
+  }
+]
+```
+
+### Example 2: Update discount percentage for a specific category
 
 The example updates the discount percentage for "Desks" category in the first matching promotion event.
 
@@ -91,7 +141,7 @@ db.stores.updateOne(
 )
 ```
 
-### Example 2: Update sales category total
+### Example 3: Update sales category total
 
 The example updates the total sales for a specific category using the `$ (positional operator)`.