Enhance branch management with foreign key relation handling

- Updated `BranchesModule` to include foreign key relations in list and write responses, ensuring they are represented as nested objects using `pickRelation`.
- Introduced new `relation-response.mdc` file to define guidelines for embedding foreign key relations.
- Modified `BranchesRepository` to support fetching related `division`, `createdByUser`, and `updatedByUser` data.
- Updated DTOs and service methods to reflect changes in response structure, removing direct foreign key IDs.
- Added unit tests to validate the new relation handling in branches service and repository.
- Enhanced e2e tests to verify the correct structure of branch responses with nested relations.

src/common/http/response/index.ts

@@ -22,3 +22,13 @@ export {
   PAGINATION_DEFAULT_LIMIT,
   PAGINATION_MAX_LIMIT,
 } from './pagination.constants';
+export {
+  DEFAULT_RELATION_FIELDS,
+  pickDefaultRelation,
+  pickRelation,
+  pickUserRelation,
+  USER_RELATION_FIELDS,
+  type DefaultRelation,
+  type UserRelation,
+} from './relation-fields';
+export { DefaultRelationDto, UserRelationDto } from './relation.dto';

src/common/http/response/relation-fields.spec.ts

@@ -0,0 +1,78 @@
+import {
+  DEFAULT_RELATION_FIELDS,
+  pickDefaultRelation,
+  pickRelation,
+  pickUserRelation,
+  USER_RELATION_FIELDS,
+} from './relation-fields';
+
+describe('pickRelation', () => {
+  const catalog = {
+    id: 'div-1',
+    code: 'JKT',
+    name: 'Jakarta',
+    status: 'active',
+    extra: 'secret',
+  };
+
+  const user = {
+    id: 'user-1',
+    username: 'admin',
+    passwordHash: 'hashed',
+  };
+
+  it('picks default id, code, name fields', () => {
+    expect(pickRelation(catalog, DEFAULT_RELATION_FIELDS)).toEqual({
+      id: 'div-1',
+      code: 'JKT',
+      name: 'Jakarta',
+    });
+  });
+
+  it('picks a custom field list for users', () => {
+    expect(pickRelation(user, USER_RELATION_FIELDS)).toEqual({
+      id: 'user-1',
+      username: 'admin',
+    });
+  });
+
+  it('returns null for null or undefined sources', () => {
+    const missing: typeof catalog | null = null;
+    const unset: typeof catalog | undefined = undefined;
+    expect(
+      pickRelation<typeof catalog, (typeof DEFAULT_RELATION_FIELDS)[number]>(
+        missing,
+        DEFAULT_RELATION_FIELDS,
+      ),
+    ).toBeNull();
+    expect(
+      pickRelation<typeof catalog, (typeof DEFAULT_RELATION_FIELDS)[number]>(
+        unset,
+        DEFAULT_RELATION_FIELDS,
+      ),
+    ).toBeNull();
+  });
+
+  it('does not copy fields outside the list', () => {
+    const picked = pickRelation(catalog, DEFAULT_RELATION_FIELDS);
+    expect(picked).not.toHaveProperty('status');
+    expect(picked).not.toHaveProperty('extra');
+  });
+});
+
+describe('pickDefaultRelation / pickUserRelation', () => {
+  it('maps catalog and user sources without leaking extra fields', () => {
+    expect(
+      pickDefaultRelation({
+        id: 'div-1',
+        code: 'JKT',
+        name: 'Jakarta',
+      }),
+    ).toEqual({ id: 'div-1', code: 'JKT', name: 'Jakarta' });
+    expect(pickDefaultRelation(null)).toBeNull();
+    expect(pickUserRelation({ id: 'user-1', username: 'admin' })).toEqual({
+      id: 'user-1',
+      username: 'admin',
+    });
+  });
+});

src/common/http/response/relation-fields.ts

@@ -0,0 +1,42 @@
+export const DEFAULT_RELATION_FIELDS = ['id', 'code', 'name'] as const;
+export const USER_RELATION_FIELDS = ['id', 'username'] as const;
+
+export type DefaultRelation = {
+  readonly id: string;
+  readonly code: string;
+  readonly name: string;
+};
+
+export type UserRelation = {
+  readonly id: string;
+  readonly username: string;
+};
+
+export function pickRelation<T, K extends keyof NonNullable<T>>(
+  source: T | null | undefined,
+  fields: readonly K[],
+): Pick<NonNullable<T>, K> | null {
+  if (source == null) {
+    return null;
+  }
+  const result = {} as Pick<NonNullable<T>, K>;
+  for (const field of fields) {
+    result[field] = source[field];
+  }
+  return result;
+}
+
+export function pickDefaultRelation(
+  source: DefaultRelation | null | undefined,
+): DefaultRelation | null {
+  return pickRelation(source, DEFAULT_RELATION_FIELDS);
+}
+
+export function pickUserRelation(source: UserRelation): UserRelation {
+  return (
+    pickRelation(source, USER_RELATION_FIELDS) ?? {
+      id: source.id,
+      username: source.username,
+    }
+  );
+}

src/common/http/response/relation.dto.ts

@@ -0,0 +1,20 @@
+import { ApiProperty } from '@nestjs/swagger';
+
+export class DefaultRelationDto {
+  @ApiProperty({ format: 'uuid' })
+  id!: string;
+
+  @ApiProperty()
+  code!: string;
+
+  @ApiProperty()
+  name!: string;
+}
+
+export class UserRelationDto {
+  @ApiProperty({ format: 'uuid' })
+  id!: string;
+
+  @ApiProperty()
+  username!: string;
+}