Merge pull request #15 from SELab-2/chore/database-setup

chore(backend): Database setup

.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/.env.development.example

@@ -0,0 +1,6 @@
+DWENGO_PORT=3000
+DWENGO_DB_HOST=localhost
+DWENGO_DB_PORT=5431
+DWENGO_DB_USERNAME=postgres
+DWENGO_DB_PASSWORD=postgres
+DWENGO_DB_UPDATE=true

backend/.env.test

@@ -0,0 +1,3 @@
+PORT=3000
+DWENGO_DB_UPDATE=true
+DWENGO_DB_NAME=":memory:"

backend/config/db/init.sql

@@ -1,2 +0,0 @@
--- Create the database
-CREATE DATABASE dwengo;

backend/package.json

@@ -11,18 +11,19 @@
         "format": "prettier --write src/",
         "format-check": "prettier --check src/",
         "lint": "eslint . --fix",
-        "test:unit": "vitest --run"
+        "test:unit": "vitest"
     },
     "dependencies": {
-        "@mikro-orm/core": "^6.4.6",
-        "@mikro-orm/postgresql": "^6.4.6",
-        "@mikro-orm/reflection": "^6.4.6",
-        "@types/js-yaml": "^4.0.9",
-        "@mikro-orm/sqlite": "^6.4.6",
-        "@mikro-orm/reflection": "^6.4.6",
+        "@mikro-orm/core": "6.4.6",
+        "@mikro-orm/postgresql": "6.4.6",
+        "@mikro-orm/sqlite": "6.4.6",
+        "@mikro-orm/reflection": "6.4.6",
         "dotenv": "^16.4.7",
         "express": "^5.0.1",
-        "js-yaml": "^4.1.0"
+        "uuid": "^11.1.0",
+        "express": "^5.0.1",
+        "js-yaml": "^4.1.0",
+        "@types/js-yaml": "^4.0.9",
     },
     "devDependencies": {
         "@mikro-orm/cli": "^6.4.6",

backend/src/app.ts

@@ -1,5 +1,7 @@
 import express, { Express, Response } from 'express';
-import initORM from './orm.js';
+import { initORM } from './orm.js';
+import { EnvVars, getNumericEnvVar } from './util/envvars.js';
+
 import themeRoutes from './routes/themes.js';
 
 import studentRouter from './routes/student';
@@ -11,7 +13,7 @@ import questionRouter from './routes/question';
 import loginRouter from './routes/login';
 
 const app: Express = express();
-const port: string | number = process.env.PORT || 3000;
+const port: string | number = getNumericEnvVar(EnvVars.Port);
 
 
 // TODO Replace with Express routes
@@ -39,4 +41,4 @@ async function startServer() {
     });
 }
 
-startServer();
+await startServer();

backend/src/data/assignments/assignment-repository.ts

@@ -0,0 +1,18 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Assignment } from '../../entities/assignments/assignment.entity.js';
+import { Class } from '../../entities/classes/class.entity.js';
+
+export class AssignmentRepository extends DwengoEntityRepository<Assignment> {
+    public findByClassAndId(
+        within: Class,
+        id: number
+    ): Promise<Assignment | null> {
+        return this.findOne({ within: within, id: id });
+    }
+    public findAllAssignmentsInClass(within: Class): Promise<Assignment[]> {
+        return this.findAll({ where: { within: within } });
+    }
+    public deleteByClassAndId(within: Class, id: number): Promise<void> {
+        return this.deleteWhere({ within: within, id: id });
+    }
+}

backend/src/data/assignments/group-repository.ts

@@ -0,0 +1,29 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Group } from '../../entities/assignments/group.entity.js';
+import { Assignment } from '../../entities/assignments/assignment.entity.js';
+
+export class GroupRepository extends DwengoEntityRepository<Group> {
+    public findByAssignmentAndGroupNumber(
+        assignment: Assignment,
+        groupNumber: number
+    ): Promise<Group | null> {
+        return this.findOne({
+            assignment: assignment,
+            groupNumber: groupNumber,
+        });
+    }
+    public findAllGroupsForAssignment(
+        assignment: Assignment
+    ): Promise<Group[]> {
+        return this.findAll({ where: { assignment: assignment } });
+    }
+    public deleteByAssignmentAndGroupNumber(
+        assignment: Assignment,
+        groupNumber: number
+    ) {
+        return this.deleteWhere({
+            assignment: assignment,
+            groupNumber: groupNumber,
+        });
+    }
+}

backend/src/data/assignments/submission-repository.ts

@@ -0,0 +1,61 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Group } from '../../entities/assignments/group.entity.js';
+import { Submission } from '../../entities/assignments/submission.entity.js';
+import { LearningObjectIdentifier } from '../../entities/content/learning-object-identifier.js';
+import { Student } from '../../entities/users/student.entity.js';
+
+export class SubmissionRepository extends DwengoEntityRepository<Submission> {
+    public findSubmissionByLearningObjectAndSubmissionNumber(
+        loId: LearningObjectIdentifier,
+        submissionNumber: number
+    ): Promise<Submission | null> {
+        return this.findOne({
+            learningObjectHruid: loId.hruid,
+            learningObjectLanguage: loId.language,
+            learningObjectVersion: loId.version,
+            submissionNumber: submissionNumber,
+        });
+    }
+
+    public findMostRecentSubmissionForStudent(
+        loId: LearningObjectIdentifier,
+        submitter: Student
+    ): Promise<Submission | null> {
+        return this.findOne(
+            {
+                learningObjectHruid: loId.hruid,
+                learningObjectLanguage: loId.language,
+                learningObjectVersion: loId.version,
+                submitter: submitter,
+            },
+            { orderBy: { submissionNumber: 'DESC' } }
+        );
+    }
+
+    public findMostRecentSubmissionForGroup(
+        loId: LearningObjectIdentifier,
+        group: Group
+    ): Promise<Submission | null> {
+        return this.findOne(
+            {
+                learningObjectHruid: loId.hruid,
+                learningObjectLanguage: loId.language,
+                learningObjectVersion: loId.version,
+                onBehalfOf: group,
+            },
+            { orderBy: { submissionNumber: 'DESC' } }
+        );
+    }
+
+    public deleteSubmissionByLearningObjectAndSubmissionNumber(
+        loId: LearningObjectIdentifier,
+        submissionNumber: number
+    ): Promise<void> {
+        return this.deleteWhere({
+            learningObjectHruid: loId.hruid,
+            learningObjectLanguage: loId.language,
+            learningObjectVersion: loId.version,
+            submissionNumber: submissionNumber,
+        });
+    }
+}

backend/src/data/classes/class-join-request-repository.ts

@@ -0,0 +1,16 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Class } from '../../entities/classes/class.entity.js';
+import { ClassJoinRequest } from '../../entities/classes/class-join-request.entity.js';
+import { Student } from '../../entities/users/student.entity.js';
+
+export class ClassJoinRequestRepository extends DwengoEntityRepository<ClassJoinRequest> {
+    public findAllRequestsBy(requester: Student): Promise<ClassJoinRequest[]> {
+        return this.findAll({ where: { requester: requester } });
+    }
+    public findAllOpenRequestsTo(clazz: Class): Promise<ClassJoinRequest[]> {
+        return this.findAll({ where: { class: clazz } });
+    }
+    public deleteBy(requester: Student, clazz: Class): Promise<void> {
+        return this.deleteWhere({ requester: requester, class: clazz });
+    }
+}

backend/src/data/classes/class-repository.ts

@@ -0,0 +1,11 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Class } from '../../entities/classes/class.entity.js';
+
+export class ClassRepository extends DwengoEntityRepository<Class> {
+    public findById(id: string): Promise<Class | null> {
+        return this.findOne({ classId: id });
+    }
+    public deleteById(id: string): Promise<void> {
+        return this.deleteWhere({ classId: id });
+    }
+}

backend/src/data/classes/teacher-invitation-repository.ts

@@ -0,0 +1,31 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Class } from '../../entities/classes/class.entity.js';
+import { TeacherInvitation } from '../../entities/classes/teacher-invitation.entity.js';
+import { Teacher } from '../../entities/users/teacher.entity.js';
+
+export class TeacherInvitationRepository extends DwengoEntityRepository<TeacherInvitation> {
+    public findAllInvitationsForClass(
+        clazz: Class
+    ): Promise<TeacherInvitation[]> {
+        return this.findAll({ where: { class: clazz } });
+    }
+    public findAllInvitationsBy(sender: Teacher): Promise<TeacherInvitation[]> {
+        return this.findAll({ where: { sender: sender } });
+    }
+    public findAllInvitationsFor(
+        receiver: Teacher
+    ): Promise<TeacherInvitation[]> {
+        return this.findAll({ where: { receiver: receiver } });
+    }
+    public deleteBy(
+        clazz: Class,
+        sender: Teacher,
+        receiver: Teacher
+    ): Promise<void> {
+        return this.deleteWhere({
+            sender: sender,
+            receiver: receiver,
+            class: clazz,
+        });
+    }
+}

backend/src/data/content/attachment-repository.ts

@@ -0,0 +1,16 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Attachment } from '../../entities/content/attachment.entity.js';
+import { LearningObject } from '../../entities/content/learning-object.entity.js';
+
+export class AttachmentRepository extends DwengoEntityRepository<Attachment> {
+    public findByLearningObjectAndNumber(
+        learningObject: LearningObject,
+        sequenceNumber: number
+    ) {
+        return this.findOne({
+            learningObject: learningObject,
+            sequenceNumber: sequenceNumber,
+        });
+    }
+    // This repository is read-only for now since creating own learning object is an extension feature.
+}

backend/src/data/content/learning-object-repository.ts

@@ -0,0 +1,16 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { LearningObject } from '../../entities/content/learning-object.entity.js';
+import { LearningObjectIdentifier } from '../../entities/content/learning-object-identifier.js';
+
+export class LearningObjectRepository extends DwengoEntityRepository<LearningObject> {
+    public findByIdentifier(
+        identifier: LearningObjectIdentifier
+    ): Promise<LearningObject | null> {
+        return this.findOne({
+            hruid: identifier.hruid,
+            language: identifier.language,
+            version: identifier.version,
+        });
+    }
+    // This repository is read-only for now since creating own learning object is an extension feature.
+}

backend/src/data/content/learning-path-repository.ts

@@ -0,0 +1,13 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { LearningPath } from '../../entities/content/learning-path.entity.js';
+import { Language } from '../../entities/content/language.js';
+
+export class LearningPathRepository extends DwengoEntityRepository<LearningPath> {
+    public findByHruidAndLanguage(
+        hruid: string,
+        language: Language
+    ): Promise<LearningPath | null> {
+        return this.findOne({ hruid: hruid, language: language });
+    }
+    // This repository is read-only for now since creating own learning object is an extension feature.
+}

backend/src/data/dwengo-entity-repository.ts

@@ -0,0 +1,19 @@
+import { EntityRepository, FilterQuery } from '@mikro-orm/core';
+
+export abstract class DwengoEntityRepository<
+    T extends object,
+> extends EntityRepository<T> {
+    public async save(entity: T) {
+        let em = this.getEntityManager();
+        em.persist(entity);
+        await em.flush();
+    }
+    public async deleteWhere(query: FilterQuery<T>) {
+        let toDelete = await this.findOne(query);
+        let em = this.getEntityManager();
+        if (toDelete) {
+            em.remove(toDelete);
+            await em.flush();
+        }
+    }
+}

backend/src/data/questions/answer-repository.ts

@@ -0,0 +1,33 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Answer } from '../../entities/questions/answer.entity.js';
+import { Question } from '../../entities/questions/question.entity.js';
+import { Teacher } from '../../entities/users/teacher.entity.js';
+
+export class AnswerRepository extends DwengoEntityRepository<Answer> {
+    public createAnswer(answer: {
+        toQuestion: Question;
+        author: Teacher;
+        content: string;
+    }): Promise<Answer> {
+        let answerEntity = new Answer();
+        answerEntity.toQuestion = answer.toQuestion;
+        answerEntity.author = answer.author;
+        answerEntity.content = answer.content;
+        return this.insert(answerEntity);
+    }
+    public findAllAnswersToQuestion(question: Question): Promise<Answer[]> {
+        return this.findAll({
+            where: { toQuestion: question },
+            orderBy: { sequenceNumber: 'ASC' },
+        });
+    }
+    public removeAnswerByQuestionAndSequenceNumber(
+        question: Question,
+        sequenceNumber: number
+    ): Promise<void> {
+        return this.deleteWhere({
+            toQuestion: question,
+            sequenceNumber: sequenceNumber,
+        });
+    }
+}

backend/src/data/questions/question-repository.ts

@@ -0,0 +1,45 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Question } from '../../entities/questions/question.entity.js';
+import { LearningObjectIdentifier } from '../../entities/content/learning-object-identifier.js';
+import { Student } from '../../entities/users/student.entity.js';
+
+export class QuestionRepository extends DwengoEntityRepository<Question> {
+    public createQuestion(question: {
+        loId: LearningObjectIdentifier;
+        author: Student;
+        content: string;
+    }): Promise<Question> {
+        let questionEntity = new Question();
+        questionEntity.learningObjectHruid = question.loId.hruid;
+        questionEntity.learningObjectLanguage = question.loId.language;
+        questionEntity.learningObjectVersion = question.loId.version;
+        questionEntity.author = question.author;
+        questionEntity.content = question.content;
+        return this.insert(questionEntity);
+    }
+    public findAllQuestionsAboutLearningObject(
+        loId: LearningObjectIdentifier
+    ): Promise<Question[]> {
+        return this.findAll({
+            where: {
+                learningObjectHruid: loId.hruid,
+                learningObjectLanguage: loId.language,
+                learningObjectVersion: loId.version,
+            },
+            orderBy: {
+                sequenceNumber: 'ASC',
+            },
+        });
+    }
+    public removeQuestionByLearningObjectAndSequenceNumber(
+        loId: LearningObjectIdentifier,
+        sequenceNumber: number
+    ): Promise<void> {
+        return this.deleteWhere({
+            learningObjectHruid: loId.hruid,
+            learningObjectLanguage: loId.language,
+            learningObjectVersion: loId.version,
+            sequenceNumber: sequenceNumber,
+        });
+    }
+}

backend/src/data/repositories.ts

@@ -0,0 +1,119 @@
+import {
+    AnyEntity,
+    EntityManager,
+    EntityName,
+    EntityRepository,
+} from '@mikro-orm/core';
+import { forkEntityManager } from '../orm.js';
+import { StudentRepository } from './users/student-repository.js';
+import { Student } from '../entities/users/student.entity.js';
+import { User } from '../entities/users/user.entity.js';
+import { UserRepository } from './users/user-repository.js';
+import { Teacher } from '../entities/users/teacher.entity.js';
+import { TeacherRepository } from './users/teacher-repository.js';
+import { Class } from '../entities/classes/class.entity.js';
+import { ClassRepository } from './classes/class-repository.js';
+import { ClassJoinRequest } from '../entities/classes/class-join-request.entity.js';
+import { ClassJoinRequestRepository } from './classes/class-join-request-repository.js';
+import { TeacherInvitationRepository } from './classes/teacher-invitation-repository.js';
+import { TeacherInvitation } from '../entities/classes/teacher-invitation.entity.js';
+import { Assignment } from '../entities/assignments/assignment.entity.js';
+import { AssignmentRepository } from './assignments/assignment-repository.js';
+import { GroupRepository } from './assignments/group-repository.js';
+import { Group } from '../entities/assignments/group.entity.js';
+import { Submission } from '../entities/assignments/submission.entity.js';
+import { SubmissionRepository } from './assignments/submission-repository.js';
+import { Question } from '../entities/questions/question.entity.js';
+import { QuestionRepository } from './questions/question-repository.js';
+import { Answer } from '../entities/questions/answer.entity.js';
+import { AnswerRepository } from './questions/answer-repository.js';
+import { LearningObject } from '../entities/content/learning-object.entity.js';
+import { LearningObjectRepository } from './content/learning-object-repository.js';
+import { LearningPath } from '../entities/content/learning-path.entity.js';
+import { LearningPathRepository } from './content/learning-path-repository.js';
+import { AttachmentRepository } from './content/attachment-repository.js';
+import { Attachment } from '../entities/content/attachment.entity.js';
+
+let entityManager: EntityManager | undefined;
+
+/**
+ * Execute all the database operations within the function f in a single transaction.
+ */
+export function transactional<T>(f: () => Promise<T>) {
+    entityManager?.transactional(f);
+}
+
+function repositoryGetter<T extends AnyEntity, R extends EntityRepository<T>>(
+    entity: EntityName<T>
+): () => R {
+    let cachedRepo: R | undefined;
+    return (): R => {
+        if (!cachedRepo) {
+            if (!entityManager) {
+                entityManager = forkEntityManager();
+            }
+            cachedRepo = entityManager.getRepository(entity) as R;
+        }
+        return cachedRepo;
+    };
+}
+
+/* Users */
+export const getUserRepository = repositoryGetter<User, UserRepository>(User);
+export const getStudentRepository = repositoryGetter<
+    Student,
+    StudentRepository
+>(Student);
+export const getTeacherRepository = repositoryGetter<
+    Teacher,
+    TeacherRepository
+>(Teacher);
+
+/* Classes */
+export const getClassRepository = repositoryGetter<Class, ClassRepository>(
+    Class
+);
+export const getClassJoinRequestRepository = repositoryGetter<
+    ClassJoinRequest,
+    ClassJoinRequestRepository
+>(ClassJoinRequest);
+export const getTeacherInvitationRepository = repositoryGetter<
+    TeacherInvitation,
+    TeacherInvitationRepository
+>(TeacherInvitationRepository);
+
+/* Assignments */
+export const getAssignmentRepository = repositoryGetter<
+    Assignment,
+    AssignmentRepository
+>(Assignment);
+export const getGroupRepository = repositoryGetter<Group, GroupRepository>(
+    Group
+);
+export const getSubmissionRepository = repositoryGetter<
+    Submission,
+    SubmissionRepository
+>(Submission);
+
+/* Questions and answers */
+export const getQuestionRepository = repositoryGetter<
+    Question,
+    QuestionRepository
+>(Question);
+export const getAnswerRepository = repositoryGetter<Answer, AnswerRepository>(
+    Answer
+);
+
+/* Learning content */
+export const getLearningObjectRepository = repositoryGetter<
+    LearningObject,
+    LearningObjectRepository
+>(LearningObject);
+export const getLearningPathRepository = repositoryGetter<
+    LearningPath,
+    LearningPathRepository
+>(LearningPath);
+export const getAttachmentRepository = repositoryGetter<
+    Attachment,
+    AttachmentRepository
+>(Assignment);

backend/src/data/users/student-repository.ts

@@ -0,0 +1,11 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Student } from '../../entities/users/student.entity.js';
+
+export class StudentRepository extends DwengoEntityRepository<Student> {
+    public findByUsername(username: string): Promise<Student | null> {
+        return this.findOne({ username: username });
+    }
+    public deleteByUsername(username: string): Promise<void> {
+        return this.deleteWhere({ username: username });
+    }
+}

backend/src/data/users/teacher-repository.ts

@@ -0,0 +1,11 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { Teacher } from '../../entities/users/teacher.entity.js';
+
+export class TeacherRepository extends DwengoEntityRepository<Teacher> {
+    public findByUsername(username: string): Promise<Teacher | null> {
+        return this.findOne({ username: username });
+    }
+    public deleteByUsername(username: string): Promise<void> {
+        return this.deleteWhere({ username: username });
+    }
+}

backend/src/data/users/user-repository.ts

@@ -0,0 +1,11 @@
+import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
+import { User } from '../../entities/users/user.entity.js';
+
+export class UserRepository extends DwengoEntityRepository<User> {
+    public findByUsername(username: string): Promise<User | null> {
+        return this.findOne({ username: username });
+    }
+    public deleteByUsername(username: string): Promise<void> {
+        return this.deleteWhere({ username: username });
+    }
+}

backend/src/entities/assignments/assignment.entity.ts

@@ -0,0 +1,35 @@
+import {
+    Entity,
+    Enum,
+    ManyToOne,
+    OneToMany,
+    PrimaryKey,
+    Property,
+} from '@mikro-orm/core';
+import { Class } from '../classes/class.entity.js';
+import { Group } from './group.entity.js';
+import { Language } from '../content/language.js';
+
+@Entity()
+export class Assignment {
+    @ManyToOne({ entity: () => Class, primary: true })
+    within!: Class;
+
+    @PrimaryKey({ type: 'number' })
+    id!: number;
+
+    @Property({ type: 'string' })
+    title!: string;
+
+    @Property({ type: 'text' })
+    description!: string;
+
+    @Property({ type: 'string' })
+    learningPathHruid!: string;
+
+    @Enum({ items: () => Language })
+    learningPathLanguage!: Language;
+
+    @OneToMany({ entity: () => Group, mappedBy: 'assignment' })
+    groups!: Group[];
+}

backend/src/entities/assignments/group.entity.ts

@@ -0,0 +1,15 @@
+import { Entity, ManyToMany, ManyToOne, PrimaryKey } from '@mikro-orm/core';
+import { Assignment } from './assignment.entity.js';
+import { Student } from '../users/student.entity.js';
+
+@Entity()
+export class Group {
+    @ManyToOne({ entity: () => Assignment, primary: true })
+    assignment!: Assignment;
+
+    @PrimaryKey({ type: 'integer' })
+    groupNumber!: number;
+
+    @ManyToMany({ entity: () => Student })
+    members!: Student[];
+}

backend/src/entities/assignments/submission.entity.ts

@@ -0,0 +1,31 @@
+import { Student } from '../users/student.entity.js';
+import { Group } from './group.entity.js';
+import { Entity, Enum, ManyToOne, PrimaryKey, Property } from '@mikro-orm/core';
+import { Language } from '../content/language.js';
+
+@Entity()
+export class Submission {
+    @PrimaryKey({ type: 'string' })
+    learningObjectHruid!: string;
+
+    @Enum({ items: () => Language, primary: true })
+    learningObjectLanguage!: Language;
+
+    @PrimaryKey({ type: 'string' })
+    learningObjectVersion: string = '1';
+
+    @PrimaryKey({ type: 'integer' })
+    submissionNumber!: number;
+
+    @ManyToOne({ entity: () => Student })
+    submitter!: Student;
+
+    @Property({ type: 'datetime' })
+    submissionTime!: Date;
+
+    @ManyToOne({ entity: () => Group, nullable: true })
+    onBehalfOf?: Group;
+
+    @Property({ type: 'json' })
+    content!: string;
+}

backend/src/entities/classes/class-join-request.entity.ts

@@ -0,0 +1,21 @@
+import { Entity, Enum, ManyToOne } from '@mikro-orm/core';
+import { Student } from '../users/student.entity';
+import { Class } from './class.entity';
+
+@Entity()
+export class ClassJoinRequest {
+    @ManyToOne({ entity: () => Student, primary: true })
+    requester!: Student;
+
+    @ManyToOne({ entity: () => Class, primary: true })
+    class!: Class;
+
+    @Enum(() => ClassJoinRequestStatus)
+    status!: ClassJoinRequestStatus;
+}
+
+export enum ClassJoinRequestStatus {
+    Open = 'open',
+    Accepted = 'accepted',
+    Declined = 'declined',
+}

backend/src/entities/classes/class.entity.ts

@@ -0,0 +1,25 @@
+import {
+    Collection,
+    Entity,
+    ManyToMany,
+    PrimaryKey,
+    Property,
+} from '@mikro-orm/core';
+import { v4 } from 'uuid';
+import { Teacher } from '../users/teacher.entity.js';
+import { Student } from '../users/student.entity.js';
+
+@Entity()
+export class Class {
+    @PrimaryKey()
+    classId = v4();
+
+    @Property({ type: 'string' })
+    displayName!: string;
+
+    @ManyToMany(() => Teacher)
+    teachers!: Collection<Teacher>;
+
+    @ManyToMany(() => Student)
+    students!: Collection<Student>;
+}

backend/src/entities/classes/teacher-invitation.entity.ts

@@ -0,0 +1,18 @@
+import { Entity, ManyToOne } from '@mikro-orm/core';
+import { Teacher } from '../users/teacher.entity.js';
+import { Class } from './class.entity.js';
+
+/**
+ * Invitation of a teacher into a class (in order to teach it).
+ */
+@Entity()
+export class TeacherInvitation {
+    @ManyToOne({ entity: () => Teacher, primary: true })
+    sender!: Teacher;
+
+    @ManyToOne({ entity: () => Teacher, primary: true })
+    receiver!: Teacher;
+
+    @ManyToOne({ entity: () => Class, primary: true })
+    class!: Class;
+}

backend/src/entities/content/attachment.entity.ts

@@ -0,0 +1,17 @@
+import { Entity, ManyToOne, PrimaryKey, Property } from '@mikro-orm/core';
+import { LearningObject } from './learning-object.entity.js';
+
+@Entity()
+export class Attachment {
+    @ManyToOne({ entity: () => LearningObject, primary: true })
+    learningObject!: LearningObject;
+
+    @PrimaryKey({ type: 'integer' })
+    sequenceNumber!: number;
+
+    @Property({ type: 'string' })
+    mimeType!: string;
+
+    @Property({ type: 'blob' })
+    content!: Buffer;
+}

backend/src/entities/content/language.ts

@@ -0,0 +1,6 @@
+export enum Language {
+    Dutch = 'nl',
+    French = 'fr',
+    English = 'en',
+    Germany = 'de',
+}

backend/src/entities/content/learning-object-identifier.ts

@@ -0,0 +1,9 @@
+import { Language } from './language.js';
+
+export class LearningObjectIdentifier {
+    constructor(
+        public hruid: string,
+        public language: Language,
+        public version: string
+    ) {}
+}

backend/src/entities/content/learning-object.entity.ts

@@ -0,0 +1,106 @@
+import {
+    Embeddable,
+    Embedded,
+    Entity,
+    Enum,
+    ManyToMany,
+    OneToMany,
+    PrimaryKey,
+    Property,
+} from '@mikro-orm/core';
+import { Language } from './language.js';
+import { Attachment } from './attachment.entity.js';
+import { Teacher } from '../users/teacher.entity.js';
+
+@Entity()
+export class LearningObject {
+    @PrimaryKey({ type: 'string' })
+    hruid!: string;
+
+    @Enum({ items: () => Language, primary: true })
+    language!: Language;
+
+    @PrimaryKey({ type: 'string' })
+    version: string = '1';
+
+    @ManyToMany({ entity: () => Teacher })
+    admins!: Teacher[];
+
+    @Property({ type: 'string' })
+    title!: string;
+
+    @Property({ type: 'text' })
+    description!: string;
+
+    @Property({ type: 'string' })
+    contentType!: string;
+
+    @Property({ type: 'array' })
+    keywords: string[] = [];
+
+    @Property({ type: 'array', nullable: true })
+    targetAges?: number[];
+
+    @Property({ type: 'bool' })
+    teacherExclusive: boolean = false;
+
+    @Property({ type: 'array' })
+    skosConcepts!: string[];
+
+    @Embedded({ entity: () => EducationalGoal, array: true })
+    educationalGoals: EducationalGoal[] = [];
+
+    @Property({ type: 'string' })
+    copyright: string = '';
+
+    @Property({ type: 'string' })
+    license: string = '';
+
+    @Property({ type: 'smallint', nullable: true })
+    difficulty?: number;
+
+    @Property({ type: 'integer' })
+    estimatedTime!: number;
+
+    @Embedded({ entity: () => ReturnValue })
+    returnValue!: ReturnValue;
+
+    @Property({ type: 'bool' })
+    available: boolean = true;
+
+    @Property({ type: 'string', nullable: true })
+    contentLocation?: string;
+
+    @OneToMany({ entity: () => Attachment, mappedBy: 'learningObject' })
+    attachments: Attachment[] = [];
+
+    @Property({ type: 'blob' })
+    content!: Buffer;
+}
+
+@Embeddable()
+export class EducationalGoal {
+    @Property({ type: 'string' })
+    source!: string;
+
+    @Property({ type: 'string' })
+    id!: string;
+}
+
+@Embeddable()
+export class ReturnValue {
+    @Property({ type: 'string' })
+    callbackUrl!: string;
+
+    @Property({ type: 'json' })
+    callbackSchema!: string;
+}
+
+export enum ContentType {
+    Markdown = 'text/markdown',
+    Image = 'image/image',
+    Mpeg = 'audio/mpeg',
+    Pdf = 'application/pdf',
+    Extern = 'extern',
+    Blockly = 'Blockly',
+}

backend/src/entities/content/learning-path.entity.ts

@@ -0,0 +1,66 @@
+import {
+    Embeddable,
+    Embedded,
+    Entity,
+    Enum,
+    ManyToMany,
+    OneToOne,
+    PrimaryKey,
+    Property,
+} from '@mikro-orm/core';
+import { Language } from './language.js';
+import { Teacher } from '../users/teacher.entity.js';
+
+@Entity()
+export class LearningPath {
+    @PrimaryKey({ type: 'string' })
+    hruid!: string;
+
+    @Enum({ items: () => Language, primary: true })
+    language!: Language;
+
+    @ManyToMany({ entity: () => Teacher })
+    admins!: Teacher[];
+
+    @Property({ type: 'string' })
+    title!: string;
+
+    @Property({ type: 'text' })
+    description!: string;
+
+    @Property({ type: 'blob' })
+    image!: string;
+
+    @Embedded({ entity: () => LearningPathNode, array: true })
+    nodes: LearningPathNode[] = [];
+}
+
+@Embeddable()
+export class LearningPathNode {
+    @Property({ type: 'string' })
+    learningObjectHruid!: string;
+
+    @Enum({ items: () => Language })
+    language!: Language;
+
+    @Property({ type: 'string' })
+    version!: string;
+
+    @Property({ type: 'longtext' })
+    instruction!: string;
+
+    @Property({ type: 'bool' })
+    startNode!: boolean;
+
+    @Embedded({ entity: () => LearningPathTransition, array: true })
+    transitions!: LearningPathTransition[];
+}
+
+@Embeddable()
+export class LearningPathTransition {
+    @Property({ type: 'string' })
+    condition!: string;
+
+    @OneToOne({ entity: () => LearningPathNode })
+    next!: LearningPathNode;
+}

backend/src/entities/questions/answer.entity.ts

@@ -0,0 +1,21 @@
+import { Entity, ManyToOne, PrimaryKey, Property } from '@mikro-orm/core';
+import { Question } from './question.entity';
+import { Teacher } from '../users/teacher.entity';
+
+@Entity()
+export class Answer {
+    @ManyToOne({ entity: () => Teacher, primary: true })
+    author!: Teacher;
+
+    @ManyToOne({ entity: () => Question, primary: true })
+    toQuestion!: Question;
+
+    @PrimaryKey({ type: 'integer' })
+    sequenceNumber!: number;
+
+    @Property({ type: 'datetime' })
+    timestamp: Date = new Date();
+
+    @Property({ type: 'text' })
+    content!: string;
+}

backend/src/entities/questions/question.entity.ts

@@ -0,0 +1,27 @@
+import { Entity, Enum, ManyToOne, PrimaryKey, Property } from '@mikro-orm/core';
+import { Language } from '../content/language.js';
+import { Student } from '../users/student.entity.js';
+
+@Entity()
+export class Question {
+    @PrimaryKey({ type: 'string' })
+    learningObjectHruid!: string;
+
+    @Enum({ items: () => Language, primary: true })
+    learningObjectLanguage!: Language;
+
+    @PrimaryKey({ type: 'string' })
+    learningObjectVersion: string = '1';
+
+    @PrimaryKey({ type: 'integer' })
+    sequenceNumber!: number;
+
+    @ManyToOne({ entity: () => Student })
+    author!: Student;
+
+    @Property({ type: 'datetime' })
+    timestamp: Date = new Date();
+
+    @Property({ type: 'text' })
+    content!: string;
+}

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

@@ -0,0 +1,22 @@
+import { User } from './user.entity.js';
+import { Collection, Entity, ManyToMany } from '@mikro-orm/core';
+import { Class } from '../classes/class.entity.js';
+import { Group } from '../assignments/group.entity.js';
+import { StudentRepository } from '../../data/users/student-repository.js';
+
+@Entity({ repository: () => StudentRepository })
+export class Student extends User {
+    @ManyToMany(() => Class)
+    classes!: Collection<Class>;
+
+    @ManyToMany(() => Group)
+    groups!: Collection<Group>;
+
+    constructor(
+        public username: string,
+        public firstName: string,
+        public lastName: string
+    ) {
+        super();
+    }
+}

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

@@ -0,0 +1,9 @@
+import { Collection, Entity, ManyToMany } from '@mikro-orm/core';
+import { User } from './user.entity.js';
+import { Class } from '../classes/class.entity.js';
+
+@Entity()
+export class Teacher extends User {
+    @ManyToMany(() => Class)
+    classes!: Collection<Class>;
+}

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

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

backend/src/mikro-orm.config.ts

@@ -1,12 +1,35 @@
 import { Options } from '@mikro-orm/core';
 import { PostgreSqlDriver } from '@mikro-orm/postgresql';
+import { EnvVars, getEnvVar, getNumericEnvVar } from './util/envvars.js';
+import { SqliteDriver } from '@mikro-orm/sqlite';
 
-const config: Options = {
+const entities = ['dist/**/*.entity.js'];
+const entitiesTs = ['src/**/*.entity.ts'];
+function config(testingMode: boolean = false): Options {
+    if (testingMode) {
+        return {
+            driver: SqliteDriver,
+            dbName: getEnvVar(EnvVars.DbName),
+            entities: entities,
+            entitiesTs: entitiesTs,
+
+            // Workaround: vitest: `TypeError: Unknown file extension ".ts"` (ERR_UNKNOWN_FILE_EXTENSION)
+            // (see https://mikro-orm.io/docs/guide/project-setup#testing-the-endpoint)
+            dynamicImportProvider: (id) => import(id),
+        };
+    } else {
+        return {
             driver: PostgreSqlDriver,
-    dbName: 'dwengo',
-    entities: ['dist/**/*.entity.js'],
-    entitiesTs: ['src/**/*.entity.ts'],
+            host: getEnvVar(EnvVars.DbHost),
+            port: getNumericEnvVar(EnvVars.DbPort),
+            dbName: getEnvVar(EnvVars.DbName),
+            user: getEnvVar(EnvVars.DbUsername),
+            password: getEnvVar(EnvVars.DbPassword),
+            entities: entities,
+            entitiesTs: entitiesTs,
             debug: true,
         };
+    }
+}
 
 export default config;

backend/src/orm.ts

@@ -1,6 +1,30 @@
-import { MikroORM } from '@mikro-orm/core';
+import { EntityManager, MikroORM } from '@mikro-orm/core';
 import config from './mikro-orm.config.js';
+import { EnvVars, getEnvVar } from './util/envvars.js';
 
-export default async function initORM() {
-    await MikroORM.init(config);
+let orm: MikroORM | undefined;
+export async function initORM(testingMode: boolean = false) {
+    orm = await MikroORM.init(config(testingMode));
+    // 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
+            );
+        }
+    }
+}
+export function forkEntityManager(): EntityManager {
+    if (!orm) {
+        throw Error(
+            'Accessing the Entity Manager before the ORM is fully initialized.'
+        );
+    }
+    return orm.em.fork();
 }

backend/src/util/envvars.ts

@@ -0,0 +1,45 @@
+const PREFIX = 'DWENGO_';
+const DB_PREFIX = PREFIX + 'DB_';
+
+type EnvVar = { key: string; required?: boolean; defaultValue?: any };
+
+export const EnvVars: { [key: string]: EnvVar } = {
+    Port: { key: PREFIX + 'PORT', defaultValue: 3000 },
+    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;
+    }
+}

backend/tests/data/users.test.ts

@@ -0,0 +1,33 @@
+import {setupTestApp} from "../setup-tests.js"
+import {Student} from "../../src/entities/users/student.entity.js";
+import {describe, it, expect, beforeAll} from "vitest";
+import {StudentRepository} from "../../src/data/users/student-repository.js";
+import {getStudentRepository} from "../../src/data/repositories.js";
+
+const username = "teststudent";
+const firstName = "John";
+const lastName = "Doe";
+describe("StudentRepository", () => {
+    let studentRepository: StudentRepository;
+
+    beforeAll(async () => {
+        await setupTestApp();
+        studentRepository = getStudentRepository();
+    });
+
+    it("should return the queried student after he was added", async () => {
+        await studentRepository.insert(new Student(username, firstName, lastName));
+
+        let retrievedStudent = await studentRepository.findByUsername(username);
+        expect(retrievedStudent).toBeTruthy();
+        expect(retrievedStudent?.firstName).toBe(firstName);
+        expect(retrievedStudent?.lastName).toBe(lastName);
+    });
+
+    it("should no longer return the queried student after he was removed again", async () => {
+        await studentRepository.deleteByUsername(username);
+
+        let retrievedStudent = await studentRepository.findByUsername(username);
+        expect(retrievedStudent).toBeNull();
+    });
+});

backend/tests/example.test.ts

@@ -4,6 +4,6 @@ describe("Sample test", () => {
     it("should sum to 2", () => {
         const expected = 2;
         const result = 1 + 1;
-        expect(result).toBe(expected);
+        expect(result).equals(expected);
     });
 })

backend/tests/setup-tests.ts

@@ -0,0 +1,7 @@
+import {initORM} from "../src/orm.js";
+import dotenv from "dotenv";
+
+export async function setupTestApp() {
+    dotenv.config({path: ".env.test"});
+    await initORM(true);
+}

backend/vitest.config.ts

@@ -0,0 +1,8 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+    test: {
+        environment: 'node',
+        globals: true
+    }
+});

docker-compose.yml

@@ -6,11 +6,9 @@ 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
 
 volumes:
     postgres_data: