diff --git a/backend/src/data/repositories.ts b/backend/src/data/repositories.ts
index 892e7ca3..2aaef875 100644
--- a/backend/src/data/repositories.ts
+++ b/backend/src/data/repositories.ts
@@ -1,16 +1,76 @@
-import {AnyEntity, EntityName, EntityRepository} from "@mikro-orm/core";
+import {AnyEntity, EntityManager, EntityName, EntityRepository} from "@mikro-orm/core";
 import {forkEntityManager} from "../orm";
 import {StudentRepository} from "./users/student-repository";
 import {Student} from "../entities/users/student.entity";
+import {User} from "../entities/users/user.entity";
+import {UserRepository} from "./users/user-repository";
+import {Teacher} from "../entities/users/teacher.entity";
+import {TeacherRepository} from "./users/teacher-repository";
+import {Class} from "../entities/classes/class.entity";
+import {ClassRepository} from "./classes/class-repository";
+import {ClassJoinRequest} from "../entities/classes/class-join-request.entity";
+import {ClassJoinRequestRepository} from "./classes/class-join-request-repository";
+import {TeacherInvitationRepository} from "./classes/teacher-invitation-repository";
+import {TeacherInvitation} from "../entities/classes/teacher-invitation.entity";
+import {Assignment} from "../entities/assignments/assignment.entity";
+import {AssignmentRepository} from "./assignments/assignment-repository";
+import {GroupRepository} from "./assignments/group-repository";
+import {Group} from "../entities/assignments/group.entity";
+import {Submission} from "../entities/assignments/submission.entity";
+import {SubmissionRepository} from "./assignments/submission-repository";
+import {Question} from "../entities/questions/question.entity";
+import {QuestionRepository} from "./questions/question-repository";
+import {Answer} from "../entities/questions/answer.entity";
+import {AnswerRepository} from "./questions/answer-repository";
+import {LearningObject} from "../entities/content/learning-object.entity";
+import {LearningObjectRepository} from "./content/learning-object-repository";
+import {LearningPath} from "../entities/content/learning-path.entity";
+import {LearningPathRepository} from "./content/learning-path-repository";
+import {AttachmentRepository} from "./content/attachment-repository";
+import {Attachment} from "../entities/content/attachment.entity";
+
+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) {
-            cachedRepo = forkEntityManager().getRepository(entity) as R;
+            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);
diff --git a/backend/src/data/users/user-repository.ts b/backend/src/data/users/user-repository.ts
index 111244cd..65e053ac 100644
--- a/backend/src/data/users/user-repository.ts
+++ b/backend/src/data/users/user-repository.ts
@@ -1,7 +1,7 @@
 import {DwengoEntityRepository} from "../dwengo-entity-repository";
 import {User} from "../../entities/users/user.entity";
 
-export class StudentRepository extends DwengoEntityRepository<User> {
+export class UserRepository extends DwengoEntityRepository<User> {
     public findByUsername(username: string): Promise<User | null> {
         return this.findOne({username: username});
     }
diff --git a/backend/tests/data/users.test.ts b/backend/tests/data/users.test.ts
index c806f13c..1a538ba7 100644
--- a/backend/tests/data/users.test.ts
+++ b/backend/tests/data/users.test.ts
@@ -11,7 +11,7 @@ describe("StudentRepository", () => {
     let studentRepository: StudentRepository;
 
     beforeAll(async () => {
-        setupTestApp();
+        await setupTestApp();
         studentRepository = getStudentRepository();
     });