Assignment 1: "What to Eat?" — Office Cafeteria Menu API

Overview

You are building the backend for "What to Eat?" — an application that lets employees browse menus across multiple in-office cafeterias. The app tracks which food items are available for breakfast, lunch, and dinner at each restaurant, on any given date.

Your job is to implement the Service layer and Controller layer so the REST APIs work end-to-end.

---

Architecture

HTTP Request
    │
    ▼
┌──────────────────┐
│   Controller      │  ← Receives HTTP requests, calls Service, returns HTTP responses
│   (YOUR CODE)     │
└────────┬─────────┘
         │
         ▼
┌──────────────────┐
│   Service         │  ← Contains business logic, validation, calls Repository
│   (YOUR CODE)     │
└────────┬─────────┘
         │
         ▼
┌──────────────────┐
│   Repository      │  ← Stores/retrieves data from in-memory HashMaps
│   (PRE-BUILT)     │
└──────────────────┘

---

Domain Model

Restaurant

An office cafeteria/restaurant.

• id (Long) — auto-generated
• name (String) — e.g., "Cafeteria Alpha"
• location (String) — e.g., "Building A, Floor 2"

MenuItem

A food or drink item that can appear on menus.

• id (Long) — auto-generated
• name (String) — e.g., "Pancakes"
• description (String) — e.g., "Fluffy buttermilk pancakes with maple syrup"
• price (double) — e.g., 5.99
• vegetarian (boolean) — true if vegetarian
• category (ItemCategory) — one of: APPETIZER, MAIN_COURSE, DESSERT, BEVERAGE, SIDE

Menu

Links a restaurant + date + meal type to a set of menu items.

• id (Long) — auto-generated
• restaurantId (Long) — which restaurant this menu belongs to
• date (LocalDate) — the date this menu is for
• mealType (MealType) — one of: BREAKFAST, LUNCH, DINNER
• menuItemIds (List) — IDs of the items on this menu

Constraint: Only ONE menu can exist per (restaurant + date + mealType) combination. You can't have two different BREAKFAST menus for the same restaurant on the same date.

MenuResponse (DTO)

When returning a menu via the API, we enrich it with full details instead of raw IDs:

• id, restaurantName, restaurantLocation, date, mealType
• items — list of full MenuItem objects (not just IDs)

---

What You Need to Implement

Files to edit (6 files):

#	File	What to implement
1	service/RestaurantService.java	CRUD business logic for restaurants
2	service/MenuItemService.java	CRUD business logic for menu items
3	service/MenuService.java	CRUD + query logic for menus (cross-service validation)
4	controller/RestaurantController.java	REST endpoints for restaurants
5	controller/MenuItemController.java	REST endpoints for menu items
6	controller/MenuController.java	REST endpoints for menus

Files you must NOT modify:

Everything in model/, dto/, repository/, exception/, and Assignment1Application.java.

---

API Endpoints to Implement

Restaurants — /api/restaurants

Method	Path	Description	Status Code
POST	/api/restaurants	Create a restaurant	201 Created
GET	/api/restaurants	List all restaurants	200 OK
GET	/api/restaurants/{id}	Get restaurant by ID	200 OK
PUT	/api/restaurants/{id}	Update a restaurant	200 OK
DELETE	/api/restaurants/{id}	Delete a restaurant	204 No Content

Menu Items — /api/menu-items

Method	Path	Description	Status Code
POST	/api/menu-items	Create a menu item	201 Created
GET	/api/menu-items	List all menu items	200 OK
GET	/api/menu-items/{id}	Get menu item by ID	200 OK
PUT	/api/menu-items/{id}	Update a menu item	200 OK
DELETE	/api/menu-items/{id}	Delete a menu item	204 No Content

Menus — /api/menus

Method	Path	Description	Status Code
POST	/api/menus	Create a menu	201 Created
GET	/api/menus	List all menus	200 OK
GET	/api/menus/{id}	Get menu by ID	200 OK
GET	/api/menus/restaurant/{restaurantId}	Get menus by restaurant	200 OK
GET	/api/menus/date/{date}	Get menus by date (yyyy-MM-dd)	200 OK
GET	/api/menus/restaurant/{restaurantId}/date/{date}	Get menus by restaurant + date	200 OK
PUT	/api/menus/{id}	Update a menu	200 OK
DELETE	/api/menus/{id}	Delete a menu	204 No Content

---

Validation Rules & Error Handling

Your services should validate inputs and throw the appropriate exceptions. The GlobalExceptionHandler (already built) will catch them and return proper HTTP error responses.

Exception	HTTP Status	When to throw
InvalidRequestException	400 Bad Request	Empty/null name, negative price, missing required fields
ResourceNotFoundException	404 Not Found	Restaurant/MenuItem/Menu with given ID doesn't exist
DuplicateResourceException	409 Conflict	Menu already exists for same restaurant + date + meal type

Specific validations:

Restaurant:

• Name must not be null or blank
• Location must not be null or blank

MenuItem:

• Name must not be null or blank
• Price must be greater than 0
• Category must not be null

Menu (most complex):

• Restaurant ID must not be null
• Date must not be null
• Meal type must not be null
• Menu item IDs list must not be null or empty
• Restaurant must exist (verify by fetching it)
• All menu items must exist (verify each one)
• No duplicate menu for same restaurant + date + meal type

---

How to Approach This

Recommended order:

1. Start with RestaurantService — simplest CRUD, gets you comfortable with the pattern
2. Then RestaurantController — wire up the service to HTTP endpoints
3. Then MenuItemService + MenuItemController — similar pattern, slightly more validation
4. Finally MenuService + MenuController — the interesting one with cross-service calls

Pattern for each Controller method:

// 1. Call the service
SomeResult result = someService.doSomething(params);

// 2. Return with the right HTTP status
return ResponseEntity.ok(result);                              // 200
return ResponseEntity.status(HttpStatus.CREATED).body(result); // 201
return ResponseEntity.noContent().build();                     // 204

Pattern for each Service method:

// 1. Validate inputs (throw InvalidRequestException if bad)
// 2. Business logic checks (throw DuplicateResourceException if conflict)
// 3. Call repository
// 4. Return result

---

Running the Application

./gradlew bootRun

The server starts at http://localhost:8080.

---

Testing Your Implementation

Option 1: Manual testing with curl

# Create a restaurant
curl -X POST http://localhost:8080/api/restaurants \
  -H "Content-Type: application/json" \
  -d '{"name": "Cafeteria Alpha", "location": "Building A, Floor 2"}'

# Create a menu item
curl -X POST http://localhost:8080/api/menu-items \
  -H "Content-Type: application/json" \
  -d '{"name": "Pancakes", "description": "Fluffy buttermilk pancakes", "price": 5.99, "vegetarian": true, "category": "MAIN_COURSE"}'

# Create a menu
curl -X POST http://localhost:8080/api/menus \
  -H "Content-Type: application/json" \
  -d '{"restaurantId": 1, "date": "2026-02-10", "mealType": "BREAKFAST", "menuItemIds": [1]}'

Option 2: Automated tests (recommended)

Run the provided Python test script:

# Make sure the Spring Boot app is running first, then:
python3 test_apis.py

The script tests all endpoints including edge cases. All tests should pass when your implementation is correct.

---

Hints

1. Optional.orElseThrow() is your friend for the "get by ID" methods:

   return repository.findById(id)
       .orElseThrow(() -> new ResourceNotFoundException("Not found with id: " + id));

2. Streams + map for converting lists:

   return menus.stream()
       .map(this::toMenuResponse)
       .toList();

3. ResponseEntity cheat sheet:

   • ResponseEntity.ok(body) → 200
   • ResponseEntity.status(HttpStatus.CREATED).body(body) → 201
   • ResponseEntity.noContent().build() → 204

4. For string validation, String.isBlank() checks for null? No — check null first:

   if (name == null || name.isBlank()) { throw ... }

---

Good luck! Start simple, test often, and build up incrementally.