Removing a specific element of a list which is an element of another list using PATCH method. Written using dropwizard

Question

I'm trying to write a PATCH api method which removes one specific element from a list of items. Note that the list of items is part of the Menu class. There aren't a lot of dropwizard resources out there, so I'm kinda stuck.

Here's all the important pieces of code – https://pastebin.com/Y9mAVZJk

Any help would mean a lot. I am a beginner when it comes to restul apis, but i've grasped the concept of Angular easily. I'm having issues with the backend, especially because it is dropwizard. It has to be dropwizard as it is an assignment, I can't change it to anything else. The databse might come later, but it is as it is right now.

public class Item {

    private String person;
    private String name;
    private Integer quantity;
    private Integer price;


     public Item(String name, int price) {

        this.person = "";
        this.quantity = 0;
        this.name = name;
        this.price = price;
      }

    public Item(String person, String name, int quantity, int price) {

        this.name = name;
        this.person = person;
        this.quantity = quantity;
        this.price = price;
    }

    @JsonProperty
    public String getPerson() {
        return this.person;
    }


    @JsonProperty
    public String getName(){
        return this.name;
    }

    @JsonProperty
    public Integer getQuantity(){
        return this.quantity;
    }

    @JsonProperty
    public Integer getPrice(){
        return this.price;
    }

}
____________________________
public class Menu {

    private Integer id;
    private String name;
    private List<Item> items;

    public Menu() { }

    public Menu(int id, String name, List<Item> items) {
        this.id = id;
        this.name = name;
        this.items = items;
    }


    @JsonProperty
    public List<Item> getItems() {
        return this.items;
    }

    @JsonProperty
    public void setItems(List<Item> items){
        this.items = items;
    }

    @JsonProperty
    public Integer getId() {

        return this.id;
    }

    @JsonProperty
    public String getName() {
        return this.name;
    }

    @JsonProperty
    public void setId(final int id) {
        this.id = id;
    }

    @JsonProperty
    public void setName(final String name) {
        this.name = name;
    }
}
_____________________________

public MenuRepository() {
        this.menus = new HashMap<>();
        for (int i=1; i<9; i++) {
            Item item = new Item("Item " + i, i+200);
            this.items.add(item);
        }

        addNewMenu(new Menu(1, "First Menu", this.items));
        addNewMenu(new Menu(2, "Second Menu", this.items));
        addNewMenu(new Menu(3, "Third Menu", this.items));
        addNewMenu(new Menu(4, "Fourth Menu", this.items));
        addNewMenu(new Menu(5, "Fifth Menu", this.items));
        addNewMenu(new Menu(6, "Sixth Menu", this.items));
        addNewMenu(new Menu(7, "Seventh Menu", this.items));

    }

    private int getNewId() {
        return counter++;
    }
 public Collection<Menu> getAllMenus() {
        return this.menus.values();
    }

    public Menu get(final int id) {
        return this.menus.get(id);
    }

    public Collection<Menu> addNewMenu(final Menu menu) {

        menu.setId(this.getNewId());
        this.menus.put(menu.getId(), menu);
        return this.menus.values();

    } 

    public Collection<Menu> removeMenu(final int id) {
        this.menus.remove(id);
        return this.menus.values();
    }

@Path("/menu")
@Produces(MediaType.APPLICATION_JSON)

public class MenuResource {

    private MenuRepository menuRepository;

    public MenuResource(final MenuRepository menuRepository) {
        this.menuRepository = menuRepository;
    }

    @GET
    @Timed
    public Collection<Menu> getAll() {
        return this.menuRepository.getAllMenus();
    }

    @GET
    @Path("/{id}")
    @Timed
    public Menu get(@PathParam("id") final int id) {


        return this.menuRepository.get(id);
    }

    @POST
    @Timed
    public Collection<Menu> post(final Menu menu) {
        return this.menuRepository.addNewMenu(menu);
    }

    @DELETE
    @Path("/{id}")
    @Timed
    public Collection<Menu> delete(@PathParam("id") final int id) {
        return this.menuRepository.removeMenu(id);
    }

EDIT: Is it possible to get the PATCH method to both add and remove items from the list?

Answer 1

I'm trying to understand your code while writing this answer.

I'd say, first of all, try formatting it a little bit better, as formatted code is easier to read not only for us, but for you.

If I remember correctly, Dropwizard bundles Jersey, which is a JAX-RS implementation. In your resource class, just use the @PATCH annotation to identify the item removal method.

You can get a hold of the List<Item> and remove the element via ListIterator<Item>.

@Path("/menu")
@Produces(MediaType.APPLICATION_JSON)
public class MenuResource {
   ...

   @PATCH
   @Path("/remove/{menuId}/{itemName}")
   public void removeMenuItem(
            @PathParam("menuId") final int menuId,
            @PathParam("itemName") final String itemName) {
      final List<Item> items = this.menuRepository.get(menuId).getItems();

      for (final ListIterator<Item> iterator = items.listIterator(); iterator.hasNext();) {
         final Item item = iterator.next();

         if (itemName.equals(item.getName())) {
            iterator.remove();
            break;
         }
      }
   }

   @PATCH
   @Path("/add/{menuId}")
   public void removeMenuItem(
            @PathParam("menuId") final int menuId,
            final Item item) {  // Item represents the Request Body
      final List<Item> items = this.menuRepository.get(menuId).getItems();
      items.add(item);
   }

Remember to add the @XmlRootElement annotation on the Item class

@XmlRootElement
public class Item { ... }

---

For the insertion/removal point, I'd say use two different methods.

You can prefix the insertion path with add, e.g. /add/{menuId} and pass the Item via request body. You can then prefix the removal path with remove e.g. /remove/{menuId}/{itemId}