feat(backend): Repositories toegevoegd, databank unit-testbaar gemaakt.

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

@@ -0,0 +1,11 @@
+import {DwengoEntityRepository} from "../dwengo-entity-repository";
+import {Student} from "../../entities/users/student.entity";
+
+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});
+    }
+}