Merge remote-tracking branch 'refs/remotes/origin/fix/databank-laat-toevoegen-van-meerdere-studenten-met-dezelfde-username-toe-#153' into feat/user-routes

# Conflicts:
#	backend/src/controllers/students.ts
#	backend/src/controllers/teachers.ts
#	backend/src/exceptions.ts
#	backend/src/interfaces/student.ts
#	backend/src/routes/router.ts
#	backend/src/routes/students.ts
#	backend/src/services/students.ts
#	backend/src/services/teachers.ts
#	frontend/src/controllers/controllers.ts

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

@@ -1,10 +1,12 @@
 import { EntityRepository, FilterQuery } from '@mikro-orm/core';
+import { EntityAlreadyExistsException } from '../exceptions/entity-already-exists-exception';
 
 export abstract class DwengoEntityRepository<T extends object> extends EntityRepository<T> {
-    public async save(entity: T) {
-        const em = this.getEntityManager();
-        em.persist(entity);
-        await em.flush();
+    public async save(entity: T, options?: { preventOverwrite?: boolean }): Promise<void> {
+        if (options?.preventOverwrite && (await this.findOne(entity))) {
+            throw new EntityAlreadyExistsException(`A ${this.getEntityName()} with this identifier already exists.`);
+        }
+        await this.getEntityManager().persistAndFlush(entity);
     }
     public async deleteWhere(query: FilterQuery<T>) {
         const toDelete = await this.findOne(query);

backend/src/data/repositories.ts

@@ -2,8 +2,6 @@ import { AnyEntity, EntityManager, EntityName, EntityRepository } from '@mikro-o
 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';

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

@@ -1,5 +1,4 @@
 import { Student } from '../../entities/users/student.entity.js';
-import { User } from '../../entities/users/user.entity.js';
 import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
 // Import { UserRepository } from './user-repository.js';
 

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

@@ -1,6 +1,5 @@
 import { Teacher } from '../../entities/users/teacher.entity.js';
 import { DwengoEntityRepository } from '../dwengo-entity-repository.js';
-import { UserRepository } from './user-repository.js';
 
 export class TeacherRepository extends DwengoEntityRepository<Teacher> {
     public findByUsername(username: string): Promise<Teacher | null> {