Database-w4-Assignment

Author: AhmadSaadeddin1987

Week4/.gitignore

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+.env
+node_modules/

Week4/homework/Ex2-Transactions/Transfer.png

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+import { transferAmount } from "./transfer.js";
+
+async function main() {
+await transferAmount(101, 102, 1000);
+}
+
+main();

Week4/homework/Ex2-Transactions/index.js

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+{
+  "name": "ex2-transactions",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "type": "module",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "dotenv": "^17.2.3",
+    "mongodb": "^7.0.0"
+  }
+}

Week4/homework/Ex2-Transactions/package-lock.json

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+import { MongoClient } from "mongodb";
+import dotenv from "dotenv";
+dotenv.config();
+
+const client = new MongoClient(process.env.MONGO_URI);
+
+export async function setup() {
+try {
+await client.connect();
+const db = client.db("databaseWeek4");
+
+const accounts = db.collection("accounts");
+const accountChanges = db.collection("account_changes");
+
+// Clear previous data
+await accounts.deleteMany({});
+await accountChanges.deleteMany({});
+
+// Insert sample accounts
+await accounts.insertMany([
+    { account_number: 101, balance: 5000 },
+    { account_number: 102, balance: 3000 }
+]);
+
+console.log("Setup done: collections created and sample data inserted.");
+} catch (err) {
+console.error(err);
+} finally {
+await client.close();
+}
+}
+

Week4/homework/Ex2-Transactions/package.json

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+import { MongoClient } from "mongodb";
+import dotenv from "dotenv";
+dotenv.config();
+
+const client = new MongoClient(process.env.MONGO_URI);
+
+export async function transferAmount(fromAcc, toAcc, amount) {
+const session = client.startSession();
+
+try {
+await client.connect();
+const db = client.db("databaseWeek4");
+const accounts = db.collection("accounts");
+const accountChanges = db.collection("account_changes");
+
+await session.withTransaction(async () => {
+    // Deduct from sender
+    const fromResult = await accounts.updateOne(
+    { account_number: fromAcc },
+    { $inc: { balance: -amount } },
+    { session }
+    );
+
+    // Add to receiver
+    const toResult = await accounts.updateOne(
+    { account_number: toAcc },
+    { $inc: { balance: amount } },
+    { session }
+    );
+
+    // Log changes
+    await accountChanges.insertMany([
+    {
+        account_number: fromAcc,
+        amount: -amount,
+        changed_date: new Date(),
+        remark: `Transferred ${amount} to account ${toAcc}`
+    },
+    {
+        account_number: toAcc,
+        amount: amount,
+        changed_date: new Date(),
+        remark: `Received ${amount} from account ${fromAcc}`
+    }
+    ], { session });
+});
+
+console.log(`Transaction successful: ${amount} transferred from ${fromAcc} to ${toAcc}`);
+} catch (err) {
+console.error("Transaction failed:", err);
+} finally {
+await session.endSession();
+await client.close();
+}
+}

Week4/homework/Ex2-Transactions/setup.js

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+import fs from "fs";
+import csv from "csv-parser";
+import { MongoClient } from "mongodb";
+import dotenv from "dotenv";
+dotenv.config();
+
+const client = new MongoClient(process.env.MONGO_URI);
+
+async function run() {
+try {
+await client.connect();
+console.log("Connected to MongoDB");
+
+const db = client.db("databaseWeek4");
+const collection = db.collection("population");
+
+const results = [];
+
+fs.createReadStream("./homework/ex1-aggregation/population_pyramid_1950-2022.csv")
+    .pipe(csv())
+    .on("data", (row) => {
+    results.push({
+        Country: row.Country,
+        Year: Number(row.Year),
+        Age: row.Age,
+        M: Number(row.M),
+        F: Number(row.F),
+    });
+    })
+    .on("end", async () => {
+    const inserted = await collection.insertMany(results);
+    console.log("Inserted:", inserted.insertedCount, "documents");
+    await client.close();
+    });
+
+} catch (err) {
+console.error(err);
+}
+}
+
+run();