chore: First entities setup, made connection to database, added central API to request environment variables for our app.

.gitignore

@@ -43,6 +43,9 @@ build/Release
 node_modules/
 jspm_packages/
 
+# package-lock.json
+backend/package-lock.json
+
 # Snowpack dependency directory (https://snowpack.dev/)
 web_modules/
 
@@ -643,6 +646,7 @@ FodyWeavers.xsd
 # Icon must end with two \r
 Icon
 
+
 # Thumbnails
 ._*
 

backend/src/entities/users/student.entity.ts

@@ -0,0 +1,6 @@
+import {User} from "./user.entity";
+import { Entity } from '@mikro-orm/core';
+
+@Entity()
+export class Student extends User {
+}

backend/src/entities/users/teacher.entity.ts

@@ -0,0 +1,7 @@
+import { Entity } from '@mikro-orm/core';
+import {User} from "./user.entity";
+
+@Entity()
+export class Teacher extends User {
+
+}

backend/src/entities/users/user.entity.ts

@@ -1,9 +1,9 @@
 import { Entity, PrimaryKey, Property } from '@mikro-orm/core';
 
-@Entity()
+@Entity({abstract: true})
 export class User {
-    @PrimaryKey({ type: 'number' })
-    id!: number;
+    @PrimaryKey({type: "string"})
+    username!: string;
 
     @Property()
     firstName: string = '';

backend/src/mikro-orm.config.ts

@@ -1,9 +1,14 @@
 import {Options} from '@mikro-orm/core';
-import { PostgreSqlDriver } from '@mikro-orm/postgresql';
+import {PostgreSqlDriver} from "@mikro-orm/postgresql";
+import {EnvVars, getEnvVar, getNumericEnvVar} from "./util/envvars";
 
 const config: Options = {
     driver: PostgreSqlDriver,
-    dbName: 'dwengo',
+    host: getEnvVar(EnvVars.DbHost, {required: true}),
+    port: getNumericEnvVar(EnvVars.DbPort, {defaultValue: 5432}),
+    dbName: getEnvVar(EnvVars.DbName, {defaultValue: "dwengo"}),
+    user: getEnvVar(EnvVars.DbUsername, {required: true}),
+    password: getEnvVar(EnvVars.DbPassword, {required: true}),
     entities: ['dist/**/*.entity.js'],
     entitiesTs: ['src/**/*.entity.ts'],
     debug: true,

backend/src/orm.ts

@@ -1,6 +1,19 @@
 import { MikroORM } from '@mikro-orm/core';
 import config from './mikro-orm.config.js';
+import {EnvVars, getEnvVar} from "./util/envvars";
 
 export default async function initORM() {
-    await MikroORM.init(config);
+    const orm = await MikroORM.init(config);
+
+    // Update the database scheme if necessary and enabled.
+    if (getEnvVar(EnvVars.DbUpdate)) {
+        await orm.schema.updateSchema();
+    } else {
+        const diff = await orm.schema.getUpdateSchemaSQL();
+        if (diff) {
+            throw Error("The database structure needs to be updated in order to fit the new database structure " +
+                "of the app. In order to do so automatically, set the environment variable DWENGO_DB_UPDATE to true. " +
+                "The following queries will then be executed:\n" + diff)
+        }
+    }
 }

backend/src/util/envvars.ts

@@ -0,0 +1,42 @@
+const PREFIX = "DWENGO_";
+const DB_PREFIX = PREFIX + "DB_";
+
+type EnvVar = {[key: string]: {name: string, required?: boolean, defaultValue?: boolean}};
+
+export const EnvVars: EnvVar = {
+    DbHost: {key: DB_PREFIX + "HOST", required: true},
+    DbPort: {key: DB_PREFIX + "PORT", defaultValue: 5432},
+    DbName: {key: DB_PREFIX + "NAME", defaultValue: "dwengo"},
+    DbUsername: {key: DB_PREFIX + "USERNAME", required: true},
+    DbPassword: {key: DB_PREFIX + "PASSWORD", required: true},
+    DbUpdate: {key: DB_PREFIX + "UPDATE", defaultValue: false},
+} as const;
+
+/**
+ * Returns the value of the given environment variable if it is set.
+ * Otherwise,
+ * - throw an error if the environment variable was required,
+ * - return the default value if there is one and it was not required,
+ * - return an empty string if the environment variable is not required and there is also no default.
+ * @param envVar The properties of the environment variable (from the EnvVar object).
+ */
+export function getEnvVar(envVar: EnvVar): string {
+    const value: string | undefined = process.env[envVar.key];
+    if (value) {
+        return value;
+    } else if (envVar.required) {
+        throw new Error(`Missing environment variable: ${envVar.key}`);
+    } else {
+        return envVar.defaultValue || "";
+    }
+}
+
+export function getNumericEnvVar(envVar: EnvVar): number {
+    const valueString = getEnvVar(envVar);
+    const value = parseInt(valueString);
+    if (isNaN(value)) {
+        throw new Error(`Invalid value for environment variable ${envVar.key}: ${valueString}. Expected a number.`)
+    } else {
+        return value;
+    }
+}

docker-compose.yml

@@ -6,8 +6,7 @@ services:
       POSTGRES_PASSWORD: postgres
       POSTGRES_DB: postgres
     ports:
-      - "5432:5432"
-    network_mode: "host"
+      - "5431:5432"
     volumes:
         - postgres_data:/var/lib/postgresql/data
         - ./backend/config/db/init.sql:/docker-entrypoint-initdb.d/init.sql