Lecture 7_8 advanced web technologies ppt

Lecture 7_8 advanced web technologies ppt

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  Advanced Web Technologies CSC337 Lecture 7& 8 Beginning Node.js, Express & MongoDB Development, Lim, G., Amazon, 2019.
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  Lecture 7 MongoDB, DatabaseCreation, Collections, Schemas, and its Access with Aggregate Functions. Greg : Ch 8,9
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  What is MongoDB? •MongoDB is a NoSQL database (document-oriented). • Stores data in JSON-like documents (called BSON — Binary JSON). • Flexible schema . • Very scalable, widely used in real-world apps. • Schema = the structure/rules for documents. • MongoDB default = schema-less (flexible).
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  Why you wouldused MongoDB? I would use MongoDB in projects where data is dynamic, scalability is required, and I am working with a JavaScript- based stack. However, I would avoid MongoDB in systems that require complex joins, strict relational integrity, and heavy transactional consistency like banking systems.
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  Architecture Mode BestFor Standalone Dev/Test, small apps Replica Set Production, high availability Sharding Large-scale, high-volume apps Cloud Atlas Quick deployment, managed service, global access
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  Question Answer What isreplication? Copying data across multiple servers for redundancy and high availability. What is a replica set? Group of MongoDB servers with one Primary (writes) and multiple Secondaries (reads/backup). What is sharding? Horizontal scaling; distributes data across multiple servers using a shard key. Horizontal add more servers. → Vertical upgrade a single server’s → CPU/RAM/storage.
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  Default port ofMongoDB: 27017
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  MongoDB Download link https://www.mongodb.com/try/download/community
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  Video Tutorial Guidefor Installation https://www.youtube.com/watch?v=IW8ptYqX_6k
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  Key Terms inMongoDB
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  Database • A containerfor collections. • Equivalent to a database in SQL. • One MongoDB server can have multiple databases. Example use schoolDB
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  Collection • A groupof documents. • Equivalent to a table in SQL. • Does not enforce a schema (but you can use schema validation). Example db.createCollection("students")
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  Document • The basicunit of data in MongoDB. • Stored as BSON (Binary JSON), but looks like JSON. • Equivalent to a row in SQL. Example: { "name": "Alice", "age": 22, "major": "CS" }
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  Field • A key–valuepair inside a document. • Equivalent to a column in SQL. { "name": "Bob", "age": 20 } // Here, "name" and "age" are fields.
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  _id • A uniqueidentifier for every document (primary key). • Automatically generated if not provided. • Usually an ObjectId (12-byte unique value). Example { "_id": ObjectId("64f28d1..."), "name": "Charlie" }
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  BSON (Binary JSON) •Internal storage format of MongoDB. • Supports extra data types (like Date, Decimal128) beyond JSON.
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  MQL (MongoDB QueryLanguage) • The language used to interact with MongoDB. • Syntax is JSON-like. Example: db.students.find({ age: { $gt: 20 } })
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  CRUD Operations • CreateinsertOne(), insertMany() → • Read find(), findOne() → • Update updateOne(), updateMany() → • Delete deleteOne(), deleteMany() →
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  Index • A specialdata structure to speed up queries. • Works like an index in a book (quick lookup). Example: db.students.createIndex({ name: 1 })
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  Aggregation • A frameworkfor advanced data processing (like SQL’s GROUP BY, JOIN, HAVING). • Uses pipeline stages ($match, $group, $project, $sort, $lookup). Example: db.students.aggregate([ { $group: { _id: "$major", avgAge: { $avg: "$age" } } } ])
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  Pipeline • A sequenceof stages in aggregation. • Each stage transforms the data and passes it to the next. • Order of stages (always remember MGPSL): MATCH GROUP PROJECT SORT LIMIT → → → →
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  $ Operators • Specialkeywords used in queries/aggregation. • Example categories: • Comparison operators: $eq, $gt, $lt • Logical operators: $and, $or, $not • Update operators: $set, $inc, $push Example db.students.updateOne({ name: "Alice" }, { $inc: { age: 1 } })
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  University Management Systemwith MongoDB (Problem Statement) • The university wants to build a database system to manage students, teachers, and courses. The system should: • Store details of students and teachers. • Allow inserting, updating, and deleting records. • Validate teacher records using schema rules. • Generate reports using aggregation queries. • You are hired as a MongoDB developer. Implement the system step by step
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  Step 1: CreateDatabase use universityDB • This creates the universityDB database
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  Step 2: CreateCollections • db.createCollection("students") • db.createCollection("teachers") • db.createCollection("courses")
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  Step 3: InsertStudent Records db.students.insertMany([ { name: "Alice", age: 22, major: "CS", gpa: 3.5 }, { name: "Bob", age: 20, major: "Math", gpa: 3.2 }, { name: "Charlie", age: 21, major: "Physics", gpa: 3.7 }, { name: "David", age: 23, major: "CS", gpa: 3.8 } ])
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  Step 4: InsertTeacher Records (with Schema Validation) db.createCollection("teachers", { validator: { $jsonSchema: { bsonType: "object", required: ["name", "subject", "age"], properties: { name: { bsonType: "string" }, subject: { bsonType: "string" }, age: { bsonType: "int", minimum: 25 } } } } })
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  Insert valid teacherdocuments: db.teachers.insertMany([ { name: "Dr. Smith", subject: "CS", age: 45 }, { name: "Dr. Johnson", subject: "Math", age: 38 } ])
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  Step 5: InsertCourses db.courses.insertMany([ { title: "Database Systems", credits: 4, department: "CS" }, { title: "Linear Algebra", credits: 3, department: "Math" }, { title: "Quantum Mechanics", credits: 4, department: "Physics" } ])
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  Step 6: BasicQueries (CRUD) • Find all students: db.students.find() • Find students older than 21: db.students.find({ age: { $gt: 21 } }) • Update GPA of Alice: db.students.updateOne( { name: "Alice" }, { $set: { gpa: 3.9 } } )
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  Step 6: BasicQueries (CRUD)(CONT..) • Delete a student: db.students.deleteOne({ name: "Charlie" })
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  Step 7: AggregationQueries • Count students by major: db.students.aggregate([ { $group: { _id: "$major", totalStudents: { $sum: 1 } } } ]) • Average GPA per major: db.students.aggregate([ { $group: { _id: "$major", avgGPA: { $avg: "$gpa" } } } ])
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  Find top 2students with highest GPA: db.students.aggregate([ { $sort: { gpa: -1 } }, { $limit: 2 } ])
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  Ecommerce database Inserting documents into Customers(Collection) Insertingdocuments into Products(Collection)
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  Insert Orders
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  Show all customers Show all customers
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  Find customers age > 25 Update stockof Laptop from 9 to 15 After updation
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  Increase price of all Electronics by 5000 (Before) After Updation
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  Delete customers age< 23
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  Find customers fromLahore AND age > 26
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  Find products pricebetween 5000 and 60000
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  Find customers fromLahore OR Karachi
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  Sort products byprice descending
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  Show only nameand city of customers
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  Count total products, customersand orders
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  Name starts withA
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  Query Meaning {stock: 0} Finddocuments where stock is exactly 0 {stock: {$exists:true}} Find documents where stock field exists (any value) {stock: {$exists:false}} Find documents where stock field does NOT exist Products where stock exists
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  Total sales
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  Average product priceper category
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  Top spending customer
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  Add discount field(10% if total > 50000)
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  Join orders withcustomers Lookup works as left outer join Documents with age < 23 were deleted
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  Join orders withcustomers (Output)
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  Join orders withproducts
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  Create index onproduct name Drop index on product name
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  Lecture 8 Implementation ofMongoDB Client Connector with Node.JS (Mongo Client). Greg : Ch 10
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  What is MongoClient? •MongoClient is the official MongoDB driver for Node.js. • It allows your Node.js application to connect to a MongoDB database, run queries, and perform CRUD + Aggregation operations. • Think of it as the “bridge” between your Node.js code and the MongoDB server.
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  Setup
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  Step 1: InstallMongoDB Driver Run this in your Node.js project folder: • npm init -y • npm install mongodb
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  Step 2: BasicProject Structure • project/ • ├── index.js • ├── package.json
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  3. Connect toMongoDB(Code: index.js) const { MongoClient } = require("mongodb"); // Connection URL (local MongoDB) const url = "mongodb://127.0.0.1:27017"; const client = new MongoClient(url); // Database name const dbName = "universityDB";
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  3. Connect toMongoDB(Code: index.js)CONT async function main() { try { // Connect the client await client.connect(); console.log("Connected to MongoDB"); const db = client.db(dbName); const students = db.collection("students"); // Insert a document const result = await students.insertOne({ name: "Alice", age: 22, major: "CS" }); console.log("Inserted ID:", result.insertedId); // Find documents const allStudents = await students.find().toArray(); console.log("Students:", allStudents); } catch (err) { console.error("❌ Error:", err); } finally { // Close connection await client.close(); console.log(" Connection closed"); 🔒 } } main();
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  readline module • Built-inNode.js module that allows you to read input from the user via the command line (terminal/console) and write output to it. • commonly used for interactive CLI programs, like menus, prompts • don’t need to install anything—it comes with Node.js.
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  Key Features ofreadline • Read input line by line. • Prompt users for input. • Create interactive command-line interfaces. • Can be used with streams, like process.stdin (keyboard input) and process.stdout (console output).
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  Creating a Menuwith readline