Added Subject constructor

lib/Subject.js

@@ -1,11 +1,48 @@
 'use strict';
 
+const DatabaseConnectionPool = require('./DatabaseConnectionPool');
+
 class Subject {
-	subjectId;
+	/**
+	 * The id of the subject
+	 * @type {number}
+	 */
+	id;
+
+	/**
+	 * The name of the subject
+	 * @type {string}
+	 */
 	name;
 
-	constructor() {
+	/**
+	 * @param {number} subjectID - The id of the subject to fetch
+	 */
+	constructor(subjectId) {
+		const sql = `
+			select
+				subjectId as id,
+				name
+			from
+				subject
+			where
+				subjectId = ?;
+		`;
 
+		return (async () => {
+			const conn = await new DatabaseConnectionPool();
+			const record = await conn.runQuery(sql, [
+				subjectId,
+			]);
+
+			if (!record.length)
+				throw new Error('No subject found');
+
+			for (const [ k, v ] of Object.entries(record[0]))
+				this[k] = v;
+
+			return this;
+		})();
 	}
 }