Finished week 4

Author: dashaaaa21

Week4/homework/ex1-aggregation/exercise1_population.js

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+const { MongoClient } = require("mongodb");
+
+const uri = "mongodb+srv://daryna2003tk_db_user:[email protected]/dbWeek4?retryWrites=true&w=majority";
+const client = new MongoClient(uri);
+
+async function totalPopulationByCountry(countryName) {
+    try {
+        await client.connect();
+        const db = client.db("dbWeek4");
+        const collection = db.collection("population");
+
+        const cursor = collection.find({ Country: countryName });
+        const populationByYear = {};
+
+        await cursor.forEach(doc => {
+            const year = doc.Year;
+            const total = doc.M + doc.F;
+            if (!populationByYear[year]) populationByYear[year] = 0;
+            populationByYear[year] += total;
+        });
+
+        const result = Object.keys(populationByYear).sort().map(year => ({
+            _id: parseInt(year),
+            countPopulation: populationByYear[year]
+        }));
+
+        console.log(result);
+
+    } catch (err) {
+        console.error(err);
+    } finally {
+        client.close();
+    }
+}
+
+totalPopulationByCountry("Netherlands");

Week4/homework/ex1-aggregation/exercise2_population.js

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+const { MongoClient } = require("mongodb");
+
+const uri = "mongodb+srv://daryna2003tk_db_user:[email protected]/dbWeek4?retryWrites=true&w=majority";
+const client = new MongoClient(uri);
+
+async function continentPopulation(yearValue, ageValue) {
+    try {
+        await client.connect();
+        const db = client.db("dbWeek4");
+        const collection = db.collection("population");
+
+        const results = await collection.aggregate([
+            { $match: { Year: yearValue, Age: ageValue, Country: { $in: ["AFRICA", "ASIA", "EUROPE", "LATIN AMERICA AND THE CARIBBEAN", "NORTHERN AMERICA", "OCEANIA"] } } },
+            { $project: { Country: 1, Year: 1, Age: 1, M: 1, F: 1, TotalPopulation: { $add: ["$M", "$F"] } } }
+        ]).toArray();
+
+        console.log(results);
+    } catch (err) {
+        console.error(err);
+    } finally {
+        client.close();
+    }
+}
+
+continentPopulation(2020, "100+");

Week4/homework/ex1-aggregation/package-lock.json

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+{
+  "name": "ex1-aggregation",
+  "version": "1.0.0",
+  "description": "",
+  "main": "exercise1_population.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "mongodb": "^7.0.0"
+  }
+}

Week4/homework/ex1-aggregation/package.json

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+const { setup } = require("./setup");
+const { transfer } = require("./transfer");
+
+async function start() {
+    await setup();
+
+    await transfer(101, 102, 1000, "Test transfer");
+}
+
+start();