Docsp 32718 code whisperer indexes

source/code-snippets/crud/cursor.js

@@ -1,11 +1,12 @@
+// Cursor-based document retrieval
 const { MongoClient } = require("mongodb");
 const stream = require("stream");
 
-// Replace the following string with your MongoDB deployment's connection string.
+// Replace the following string with your MongoDB deployment's connection string
 const uri =
   "mongodb+srv://<user>:<password>@<cluster-url>?writeConcern=majority";
 const client = new MongoClient(uri);
-
+// Asynchronous iteration by using cursor methods
 async function asyncIteration(myColl) {
   // start async cursor example
   const cursor = myColl.find({});
@@ -15,7 +16,7 @@ async function asyncIteration(myColl) {
   }
   // end async cursor example
 }
-
+// Manual iteration using cursor methods
 async function manualIteration(myColl) {
   // start manual cursor example
   const cursor = myColl.find({});
@@ -25,30 +26,30 @@ async function manualIteration(myColl) {
   }
   // end manual cursor example
 }
-
+// Stream documents
 async function streamAPI(myColl) {
   // start stream cursor example
   const cursor = myColl.find({});
   cursor.stream().on("data", doc => console.log(doc));
   // end stream cursor example
 }
-
+// Event-based iteration using cursor events
 async function eventAPI(myColl) {
   // start event cursor example
   const cursor = myColl.find({});
   // the "data" event is fired once per document
   cursor.on("data", data => console.log(data));
   // end event cursor example
 }
-
+// Fetch all documents as an array using the toArray method
 async function fetchAll(myColl) {
   // start fetchAll cursor example
   const cursor = myColl.find({});
   const allValues = await cursor.toArray();
   // end fetchAll cursor example
   console.log(allValues.length);
 }
-
+// Rewind the cursor
 async function rewind(myColl) {
   // start rewind cursor example
   const cursor = myColl.find({});
@@ -59,7 +60,7 @@ async function rewind(myColl) {
   console.log("Second count: " + secondResult.length);
   // end rewind cursor example
 }
-
+// Close a cursor
 async function close(myColl) {
   const cursor = myColl.find({});
 

source/code-snippets/crud/pizza.js

@@ -1,3 +1,4 @@
+// CRUD (Create, Read, Update, Delete) operations 
 const { MongoClient } = require("mongodb");
 
 // Replace the following string with your MongoDB deployment's connection string.
@@ -13,8 +14,8 @@ async function run() {
   try {
     const database = client.db("test");
     const orders = database.collection("orders");
-
     // start find crud example
+    // Search for orders by name and within a specific date range
     const findResult = await orders.find({
       name: "Lemony Snicket",
       date: {
@@ -24,8 +25,8 @@ async function run() {
     });
     // end find crud example
     console.log(await findResult.toArray());
-
     // start aggregate crud example
+    // Group orders by status within the last week
     const aggregateResult = await orders.aggregate([
       {
         $match: {
@@ -46,8 +47,8 @@ async function run() {
     ]);
     // end aggregate crud example
     console.log(await aggregateResult.toArray());
-
     // start watch crud example
+    // Set up a change stream to listen for new order insertions
     const changeStream = orders.watch([
       { $match: { operationType: "insert" } },
       {
@@ -63,10 +64,10 @@ async function run() {
     });
     // end watch crud example
 
-    // force change stream to instantiate so it can see the insert
+    // Allow the change stream to instantiate so it can see the insert
     await sleep(1);
-
     // start insert crud example
+    // Insert a new order document
     const insertResult = await orders.insertOne({
       date: new Date(Date.now()),
       address: "667 Dark Avenue, San Francisco, CA, 94110",
@@ -89,8 +90,8 @@ async function run() {
     });
     // end insert crud example
     console.log(insertResult.insertedCount); // should be 1
-
     // start update crud example
+    // Update an existing order's address
     const updateResult = await orders.updateOne(
       {
         address: "667 Dark Avenue, San Francisco, CA, 94110",
@@ -103,8 +104,8 @@ async function run() {
     );
     // end update crud example
     console.log(updateResult.modifiedCount); // should be 1
-
     // start delete crud example
+    // Delete an order document based on specified conditions
     const deleteResult = await orders.deleteOne({
       address: "13 Lousy Lane",
       name: "Violet Baudelaire",
@@ -115,7 +116,7 @@ async function run() {
     });
     // end delete crud example
     console.log(deleteResult.deletedCount); // should be 0
-
+    // Close the change stream and client connection
     await changeStream.close();
   } finally {
     await client.close();

source/code-snippets/crud/theaters.js

@@ -1,12 +1,14 @@
+// Geospatial queries using proximity to a location and a specific geographic range 
 const { MongoClient } = require("mongodb");
 
 // Replace the following string with your MongoDB deployment's connection string.
 const uri =
   "mongodb+srv://<user>:<password>@<cluster-url>?writeConcern=majority";
 const client = new MongoClient(uri);
-
+// start proximity geo example
+// Find theaters within a certain proximity
 async function proximity(theaters) {
-  // start proximity geo example
+  // Define the query to find theaters near a specific location
   const query = {
     "location.geo": {
       $near: {
@@ -15,30 +17,31 @@ async function proximity(theaters) {
       },
     },
   };
-
-  // find documents based on our query
+  // Find documents based on our query
   const cursor = theaters.find(query);
   // end proximity geo example
 
-  // print a message if no documents were found
+  // Print a message if no documents were found
   if ((await theaters.countDocuments(query)) === 0) {
     console.log("No documents found!");
   }
+  // Iterate through the found documents and display them
   for await (const doc of cursor) {
     console.dir(doc);
   } 
 }
-
+// start range geo example
+// Find theaters within a specific geographic range
 async function range(theaters) {
-  // start range geo example
+  // Define the query to find theaters within a specified polygon
   const query = {
     "location.geo": {
       $geoWithin: {
         $geometry: {
           type: "Polygon",
           coordinates: [
             [
-              [-72, 40],
+              [-72, 40], // Polygon coordinates defining the range
               [-74, 41],
               [-72, 39],
               [-72, 40],
@@ -49,14 +52,15 @@ async function range(theaters) {
     },
   };
 
-  // find documents based on our query
+  // Find documents based on our query
   const cursor = theaters.find(query);
   // end range geo example
 
-  // print a message if no documents were found
+  // Print a message if no documents were found
   if ((await theaters.countDocuments(query)) === 0) {
     console.log("No documents found!");
   }
+  // Iterate through the found documents and display them
   for await (const doc of cursor) {
     console.dir(doc);
   } 

source/code-snippets/indexes/searchIndexes.js

@@ -1,7 +1,7 @@
+// Search Index operations 
 const { MongoClient } = require("mongodb");
 
-// Replace the following with your MongoDB deployment's connection
-// string.
+// Replace the following with your MongoDB deployment's connection string
 const uri =
     "mongodb+srv://<user>:<password>@<cluster-url>?writeConcern=majority";
 
@@ -17,6 +17,7 @@ async function run() {
         const collection = database.collection("<collectionName>");
 
         // start createSearchIndex example
+        // Create a search index
         const index1 = {
             name: "search1",
             definition: {
@@ -29,6 +30,7 @@ async function run() {
         // end createSearchIndex example
 
         // start listSearchIndexes example
+        // List search indexes
         const result = await collection.listSearchIndexes().toArray();
         console.log("Existing search indexes:\n");
         for (const doc in result) {
@@ -37,6 +39,7 @@ async function run() {
         // end listSearchIndexes example
 
         // start updateSearchIndex example
+        // Update a search index
         const index2 = {
             "mappings": {
                 "dynamic": true,
@@ -51,6 +54,7 @@ async function run() {
         // end updateSearchIndex example
 
         // start dropSearchIndex example
+        // Dropping (deleting) a search index
         await collection.dropSearchIndex("search1");
         // end dropSearchIndex example
     } finally {

source/code-snippets/indexes/single-field.js

@@ -1,7 +1,7 @@
+// Creating single field indexes 
 const { MongoClient } = require("mongodb");
 
-// Replace the following with your MongoDB deployment's connection
-// string.
+// Replace the following with your MongoDB deployment's connection string
 const uri =
   "mongodb+srv://<user>:<password>@<cluster-url>?writeConcern=majority";
 
@@ -20,10 +20,11 @@ async function run() {
     // end-idx
 
     // begin-query
+    // Define the query parameters
     const query = { title: "Batman" }
     const sort = { title: 1 };
     const projection = { _id: 0, title: 1 };
-
+    // Execute the query using the defined parameters
     const cursor = movies
       .find(query)
       .sort(sort)

source/code-snippets/indexes/unique.js

@@ -1,3 +1,4 @@
+// Creating a unique index 
 const { MongoClient } = require("mongodb");
 
 // Replace the following with your MongoDB deployment's connection

source/code-snippets/usage-examples/bulkWrite.js

@@ -1,4 +1,4 @@
-/* Bulk write operation */ 
+// Bulk write operation
 
 // Import MongoClient from the MongoDB node driver package
 const { MongoClient } = require("mongodb");

source/code-snippets/usage-examples/changeStream.js

@@ -1,11 +1,15 @@
+// Watch for changes in a collection by using a change stream
 import { MongoClient } from "mongodb";
 
 // Replace the uri string with your MongoDB deployment's connection string.
 const uri = "<connection string uri>";
 
 const client = new MongoClient(uri);
 
+// Declare a variable to hold the change stream
 let changeStream;
+
+// Define an asynchronous function to manage the change stream
 async function run() {
   try {
     const database = client.db("insertDB");
@@ -14,14 +18,15 @@ async function run() {
     // Open a Change Stream on the "haikus" collection
     changeStream = haikus.watch();
 
-    // Print change events
+    // Print change events as they occur
     for await (const change of changeStream) {
       console.log("Received change:\n", change);
     }
-
+    // Close the change stream when done
     await changeStream.close();
 
   } finally {
+    // Close the MongoDB client connection
     await client.close();
   }
 }