feat: group verbinding tussen databank en api aangemaakt

backend/src/services/groups.ts

@@ -0,0 +1,36 @@
+import { getAssignmentRepository, getClassRepository, getGroupRepository } from "../data/repositories";
+import { GroupDTO, mapToGroupDTO, mapToGroupDTOId } from "../interfaces/groups";
+
+export async function getGroup(
+    classId: string, 
+    assignmentNumber: number, 
+    groupNumber: number,
+    full: boolean,
+): Promise<GroupDTO | null> {
+    const classRepository = getClassRepository();
+    const cls = await classRepository.findById(classId);
+
+    if (!cls) {
+        return null;
+    }
+
+    const assignmentRepository = getAssignmentRepository();
+    const assignment = await assignmentRepository.findByClassAndId(cls, assignmentNumber);
+
+    if (!assignment) {
+        return null;
+    }
+
+    const groupRepository = getGroupRepository();
+    const group = await groupRepository.findByAssignmentAndGroupNumber(assignment, groupNumber);
+
+    if (!group) {
+        return null;
+    }
+
+    if (full) {
+        return mapToGroupDTO(group);
+    }
+
+    return mapToGroupDTOId(group);
+}