Merge pull request #7 from mongodb-developer/aggregation

Add aggregation

aggregation.js

@@ -0,0 +1,75 @@
+const { MongoClient } = require('mongodb');
+
+async function main() {
+    /**
+     * Connection URI. Update <username>, <password>, and <your-cluster-url> to reflect your cluster.
+     * See http://bit.ly/NodeDocs_lauren for more details
+     */
+    const uri = "mongodb+srv://<username>:<password>@<your-cluster-url>/test?retryWrites=true&w=majority";
+
+    /**
+     * The Mongo Client you will use to interact with your database
+     * See bit.ly/Node_MongoClient for more details
+     */
+    const client = new MongoClient(uri);
+
+    try {
+        // Connect to the MongoDB cluster
+        await client.connect();
+
+        // Make the appropriate DB calls
+
+        // Print the 10 cheapest suburbs in the Sydney, Australia market
+        await printCheapestSuburbs(client, "Australia", "Sydney", 10);
+
+    } finally {
+        // Close the connection to the MongoDB cluster
+        await client.close();
+    }
+}
+
+main().catch(console.error);
+
+/**
+ * Print the cheapest suburbs for a given market
+ * @param {MongoClient} client A MongoClient that is connected to a cluster with the sample_airbnb database
+ * @param {String} country The country for the given market
+ * @param {String} market The market you want to search
+ * @param {number} maxNumberToPrint The maximum number of suburbs to print
+ */
+async function printCheapestSuburbs(client, country, market, maxNumberToPrint) {
+    const pipeline = [
+        {
+            '$match': {
+                'bedrooms': 1,
+                'address.country': country,
+                'address.market': market,
+                'address.suburb': {
+                    '$exists': 1,
+                    '$ne': ''
+                },
+                'room_type': 'Entire home/apt'
+            }
+        }, {
+            '$group': {
+                '_id': '$address.suburb',
+                'averagePrice': {
+                    '$avg': '$price'
+                }
+            }
+        }, {
+            '$sort': {
+                'averagePrice': 1
+            }
+        }, {
+            '$limit': maxNumberToPrint
+        }
+    ];
+
+    // See http://bit.ly/Node_aggregate for the aggregate() docs
+    const aggCursor = client.db("sample_airbnb").collection("listingsAndReviews").aggregate(pipeline);
+
+    await aggCursor.forEach(airbnbListing => {
+        console.log(`${airbnbListing._id}: ${airbnbListing.averagePrice}`);
+    });
+}

template.js

@@ -0,0 +1,30 @@
+const { MongoClient } = require('mongodb');
+
+async function main() {
+    /**
+     * Connection URI. Update <username>, <password>, and <your-cluster-url> to reflect your cluster.
+     * See http://bit.ly/NodeDocs_lauren for more details
+     */
+    const uri = "mongodb+srv://<username>:<password>@<your-cluster-url>/test?retryWrites=true&w=majority";
+
+    /**
+     * The Mongo Client you will use to interact with your database
+     * See bit.ly/Node_MongoClient for more details
+     */
+    const client = new MongoClient(uri);
+
+    try {
+        // Connect to the MongoDB cluster
+        await client.connect();
+
+        // Make the appropriate DB calls
+
+    } finally {
+        // Close the connection to the MongoDB cluster
+        await client.close();
+    }
+}
+
+main().catch(console.error);
+
+// Add functions that make DB calls here