PRA03-AlexCano-ManyToManyRelationshipImplementation

_PRA/PRA03.md

@@ -0,0 +1,204 @@
+# PRA03: Implementing ManyToMany Relationships in JPA
+
+## CIFO La Violeta - FullStack IFCD0021-24 MF01-02-03
+
+In this practical exercise, you will enhance the `RestaurantManager` project by implementing a `ManyToMany` relationship between `Menu` and `MenuItem` entities using JPA and Spring Boot.
+
+<mark>You'll design, implement, and test this relationship using an in-memory H2 database </mark>and `JpaRepository`, with a focus on the automatic creation of a<mark> join table</mark> using `@JoinTable`.
+
+## Objectives
+
+Implement and test a `ManyToMany` relationship between `Menu` and `MenuItem` entities in the `RestaurantManager` project using **Spring Data JPA**, exploring both <mark>unidirectional and bidirectional relationships.</mark>
+
+### Project Base
+
+- Existing Repository: [Restaurant Manager](https://github.com/AlbertProfe/restaurantManager/commits/master/)
+- Reference Lab: [Spring Boot Lab 8.3](https://albertprofe.dev/springboot/sblab8-3.html)
+- Reference Lab: [Spring Boot Lab 8.4](https://albertprofe.dev/springboot/sblab8-4.html)
+
+### Tasks
+
+Summary tasks:
+
+- [ ] Design Entity Classes
+- [ ] Implement JPA Repositories
+- [ ] Create Service Layer
+- [ ] Develop REST Controllers
+- [ ] Configure H2 Database
+- [ ] Write Unit Tests
+- [ ] Test with Swagger API
+
+Tasks:
+
+1. **Design Entity Classes**
+
+    - Create or update the `Menu` and `MenuItem` entity classes.
+    - Implement a ManyToMany relationship between `Menu` and `MenuItem`.
+    - Use appropriate JPA annotations such as `@ManyToMany` and `@JoinTable`.
+    - <mark>Implement both unidirectional and bidirectional</mark> cases when it is possible.
+    - Address the <mark>infinite recursion issue</mark> that can lead to `StackOverflowError`.
+
+2. **Implement JPA Repositories**
+
+    - Create JPA repository interfaces for both `Menu` and `MenuItem`.
+    - ~~Add any necessary custom query methods.~~
+
+3. **Create Service Layer**
+
+    - Develop service interfaces and implementations for both entities.
+    - Include methods to handle the relationship between `Menu` and `MenuItem`.
+    - Implement CRUD operations ~~and any additional business logic.~~
+
+4. **Develop REST Controllers**
+
+    - Create REST controllers for `Menu` and `MenuItem`.
+    - Implement endpoints that demonstrate the relationship between the entities.
+    - Use appropriate HTTP methods for each operation.
+
+5. **Configure H2 Database**
+
+    - Set up the H2 in-memory database in your `application.properties` or `application.yml` file.
+    - Configure Hibernate to create the schema automatically.
+
+6. **Write Unit Tests**
+
+    - Create unit tests for your repositories, services, and controllers.
+    - Test the `ManyToMany` relationships thoroughly.
+    - Verify that CRUD operations work correctly with the relationship in place.
+
+7. **Test with Swagger API**
+
+    - Configure Swagger for your Spring Boot application.
+    - Use Swagger UI to test all implemented REST endpoints.
+    - Verify that the relationship between `Menu` and `MenuItem` is correctly represented and functional.
+
+### Example MenuItem Entity
+
+Here's a proposed example for the `MenuItem` entity:
+
+```java
+@Entity
+public class MenuItem {
+    @Id
+    @GeneratedValue(generator = "UUID")
+    @GenericGenerator(name = "UUID", strategy = "org.hibernate.id.UUIDGenerator")
+    private String id;
+
+    private String name;
+    private String description;
+    private boolean isSpicy;
+    private boolean hasGluten;
+    private boolean isAvailable;
+
+    @Enumerated(EnumType.STRING)
+    private CourseType courseType;
+
+    @ManyToMany(mappedBy = "menuItems")
+    private Set<Menu> menus = new HashSet<>();
+
+   // Default constructor
+    public MenuItem() {
+        this.id = UUID.randomUUID().toString();
+    }
+
+    // Constructors, getters, and setters
+}
+
+public enum CourseType {
+    STARTER,
+    MAIN,
+    DESSERT
+}
+```
+
+### Unidirectional vs Bidirectional ManyToMany
+
+<mark>Explore the differences between unidirectional and bidirectional </mark>`ManyToMany` relationships:
+
+- **Unidirectional**: Only one entity maintains the relationship.
+- **Bidirectional**: Both entities are aware of the relationship.
+
+Address the infinite recursion issue in bidirectional relationships that can lead to StackOverflowError when serializing to JSON.
+
+Implement a solution using  `@JsonIgnore`,`@JsonManagedReference` and `@JsonBackReference` or by customizing the JSON serialization process.
+
+
+
+**Unidirectional Relationship**
+
+- Only one entity maintains the relationship
+- Simpler to implement and manage
+- Less coupling between entities
+- May be sufficient for basic use cases
+
+**Bidirectional Relationship**
+
+- Both entities are aware of the relationship
+- Provides more flexibility in querying and navigating the relationship
+- Requires careful management to maintain consistency
+- More suitable for complex domain models
+
+**Addressing Infinite Recursion**
+
+Bidirectional relationships can lead to infinite recursion when serializing to JSON, causing a StackOverflowError. This occurs because each entity references the other, creating an endless loop during serialization.
+
+Solutions
+
+1. **@JsonIgnore Annotation**
+
+    - Apply `@JsonIgnore` to one side of the relationship
+    - Prevents the annotated property from being serialized
+    - Simple but may limit data access in some scenarios
+
+
+
+   ```java
+   public class Menu { 
+
+   @ManyToMany
+   @JsonIgnore
+   private Set<MenuItem> menuItems; 
+   }
+   ```
+
+2. **Custom Serialization**
+
+    - Implement custom serializer classes
+    - Provides fine-grained control over JSON output
+    - More complex but offers greater flexibility
+
+3. **DTO Pattern**
+
+    - Create Data Transfer Objects (DTOs) for API responses
+    - Allows explicit control over what data is transferred
+    - Separates API representation from domain model
+
+4. **Lazy Loading**
+
+    - Use lazy loading for related entities
+    - Prevents automatic loading of related entities unless explicitly requested
+    - Requires careful handling in service layer
+
+By implementing one or a combination of these solutions, you can effectively manage bidirectional relationships while avoiding infinite recursion issues in your Spring Boot application.
+
+### Submission Guidelines
+
+- Fork the existing [Restaurant Manager](https://github.com/AlbertProfe/restaurantManager/commits/master/) repository and clone it to your local environment.
+- Create a new branch named `PRA03-YourName` from the latest commit.
+- Commit your changes with clear, descriptive messages.
+- Push your branch to your forked repository.
+- Create a pull request to the AlbertProfe repository with a summary of your changes, titled:
+    - `PRA03-YourName-ManyToManyRelationshipImplementation`
+
+### Evaluation Criteria
+
+- Correct implementation of the ManyToMany relationship with automatic join table creation.
+- Proper use of JPA annotations and Spring Data JPA features.
+- Functionality of the service layer and controllers in handling the relationship.
+- Quality and coverage of unit tests.
+- Successful configuration and use of the H2 in-memory database.
+- Clarity and completeness of Swagger API documentation and tests.
+- Proper handling of bidirectional relationship and infinite recursion issues.
+- Overall code quality, organization, and documentation.
+
+Good luck with your implementation! Remember to test thoroughly and document your code clearly.

src/main/java/dev/example/restaurantManager/RestaurantManagerApplication.java

@@ -1,6 +1,8 @@
 package dev.example.restaurantManager;
 
 import dev.example.restaurantManager.utilities.CustomerDataLoader;
+import dev.example.restaurantManager.utilities.MenuDataLoader;
+import dev.example.restaurantManager.utilities.TableDataLoader;
 import org.springframework.boot.ApplicationRunner;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
@@ -14,11 +16,15 @@ public class RestaurantManagerApplication {
 	public static void main(String[] args) {
 		SpringApplication.run(RestaurantManagerApplication.class, args);
 	}
-/*
 
-	@Bean
-	public ApplicationRunner dataLoader(CustomerDataLoader customerDataLoader) {
-		return args -> customerDataLoader.createFakeCustomers();
+
+/*	@Bean
+	public ApplicationRunner dataLoader(CustomerDataLoader customerDataLoader, TableDataLoader tableDataLoader, MenuDataLoader menuDataLoader) {
+		return args -> {
+			customerDataLoader.createFakeCustomers();
+			tableDataLoader.createFakeTables();
+			menuDataLoader.createFakeMenus();
+		};
 	}
 */
 

src/main/java/dev/example/restaurantManager/controller/EatInOrderController.java

@@ -0,0 +1,88 @@
+package dev.example.restaurantManager.controller;
+
+
+import dev.example.restaurantManager.model.EatInOrderRestaurant;
+import dev.example.restaurantManager.service.EatInService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.Date;
+import java.util.List;
+
+@RequestMapping("/api/v1/eatinorder")
+@RestController
+public class EatInOrderController {
+
+    @Autowired
+    private EatInService eatInService;
+
+    //manage request by ResponseEntity with all EatInOrder
+    @GetMapping("/alleatinorders")
+
+    public ResponseEntity<List<EatInOrderRestaurant>> getAllEatInOrders(){
+        List<EatInOrderRestaurant> eatinorders = eatInService.getAllEatInOrders();
+        HttpHeaders headers = getCommonHeaders("Get alls Eat In Restaurant Orders");
+        return eatinorders !=null && !eatinorders.isEmpty()
+                ? new ResponseEntity<>(eatinorders,headers, HttpStatus.OK)
+                : new ResponseEntity<>(headers,HttpStatus.NOT_FOUND);
+    }
+
+    @PostMapping
+
+    public ResponseEntity<EatInOrderRestaurant> createEatInOrder(@RequestBody EatInOrderRestaurant eatinorder) {
+        EatInOrderRestaurant createdEatInOrder = eatInService.createEatInOrders(eatinorder);
+        HttpHeaders headers = getCommonHeaders("Create Eat In Order Restaurant");
+        return createdEatInOrder !=null
+                ?new ResponseEntity<>(createdEatInOrder, headers, HttpStatus.CREATED)
+                : new ResponseEntity<>(headers,HttpStatus.BAD_REQUEST);
+    }
+
+    @PutMapping("/{id}")
+
+    public ResponseEntity<EatInOrderRestaurant> updateEatInOrder(@PathVariable String id, @RequestBody EatInOrderRestaurant eatInOrderDetails){
+        EatInOrderRestaurant updatedEatInOrder = eatInService.updateEatInOrders(id, eatInOrderDetails);
+        HttpHeaders headers = getCommonHeaders("Update Eat In Restaurant Order");
+        return updatedEatInOrder != null
+                ? new ResponseEntity<>(updatedEatInOrder,headers,HttpStatus.OK)
+                : new ResponseEntity<>(headers,HttpStatus.NOT_FOUND);
+    }
+
+    @DeleteMapping("/{id}")
+    public ResponseEntity<Void> deleteEatInOrder(@PathVariable String id){
+        boolean deleted = eatInService.deleteEatInOrders(id);
+        HttpHeaders headers = getCommonHeaders("Delete Eat In Order Restaurant");
+        return deleted
+                ?new ResponseEntity<>(headers,HttpStatus.NO_CONTENT)
+                : new ResponseEntity<>(headers, HttpStatus.NOT_FOUND);
+
+    }
+
+    @GetMapping("{id}")
+    public ResponseEntity<EatInOrderRestaurant> getEatInOrderById(@PathVariable String id){
+        EatInOrderRestaurant eatinorder = eatInService.getEatInOrdersById(id);
+        HttpHeaders headers = getCommonHeaders("Get a Eat In Order by ID");
+        return eatinorder !=null
+                ? new ResponseEntity<>(eatinorder, headers, HttpStatus.OK)
+                : new ResponseEntity<>(headers,HttpStatus.NOT_FOUND);
+
+    }
+
+
+
+
+    private HttpHeaders getCommonHeaders(String description) {
+        HttpHeaders headers = new HttpHeaders();
+        headers.add("desc", description);
+        headers.add("content-type", "application/json");
+        headers.add("date", new Date().toString());
+        headers.add("server", "H2 Database");
+        headers.add("version", "1.0.0");
+        headers.add("eatInOrders-count",String.valueOf(eatInService.countEatInOrders()));
+        headers.add("object", "EatInOrders");
+        return headers;
+    }
+
+}