Rest Controller

// language: java
import java.net.URI;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.support.ServletUriComponentsBuilder;

@RestController
public class UserResource {

    // ... UserDaoService and Logger Autowire / initialization ...

    /**
     * Creates a new User and returns a 201 Created status
     * with the new resource's URI in the Location header.
     */
    @PostMapping("/users")
    public ResponseEntity<User> createUser(@RequestBody User user) {

        // 1. Save the new resource
        logger.debug("User to save : {}", user);
        User savedUser = userDaoService.save(user);

        // 2. Build URL to the new Resource using the current request's context
        // e.g., POST http://localhost:8080/users -> URI: http://localhost:8080/users/{id}
        URI location = ServletUriComponentsBuilder.fromCurrentRequest()
            .path("/{id}") // Append the path segment
            .buildAndExpand(savedUser.getId()) // Replaces {id} with the actual ID
            .toUri();
    
        // 3. Wrap new URL and response object in ResponseEntity
        // ResponseEntity.created(location) sets the HTTP status to 201 and the Location header
        return ResponseEntity.created(location).body(savedUser);
    }
}

// language: java
import java.util.List;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PatchMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class ItemResource {

    // 1. GET: Retrieve a resource or a collection
    @GetMapping("/items")
    public List<Item> retrieveAllItems() {
        return itemDaoService.findAll(); // Returns a list (200 OK)
    }

    // 2. GET: Retrieve a specific resource
    @GetMapping("/items/{id}")
    public Item retrieveItem(@PathVariable int id) {
        return itemDaoService.findOne(id); // Returns the Item (200 OK)
    }

    // 3. POST: Create a new resource (as discussed)
    @PostMapping("/items")
    public ResponseEntity<Item> createItem(@RequestBody Item item) {
        // ... logic for 201 Created ...
        return ResponseEntity.created(location).body(item);
    }

    // 4. PUT: Update an existing resource (full replacement)
    @PutMapping("/items/{id}")
    public ResponseEntity<Item> updateItem(@PathVariable int id, @RequestBody Item itemDetails) {
        // Update logic...
        return ResponseEntity.ok(updatedItem); // 200 OK
    }

    // 5. PATCH: Partially update an existing resource (partial modification)
    @PatchMapping("/items/{id}")
    public ResponseEntity<Item> patchItem(@PathVariable int id, @RequestBody Item itemPatch) {
        // Partial update logic...
        return ResponseEntity.ok(patchedItem); // 200 OK
    }

    // 6. DELETE: Remove a resource
    @DeleteMapping("/items/{id}")
    public ResponseEntity<Void> deleteItem(@PathVariable int id) {
        itemDaoService.deleteById(id);
        return ResponseEntity.noContent().build(); // 204 No Content
    }
}