json - single custom deserializer for all objects as their ids or embedded whole objects during POST/PUT

Question

@Entity
public Product {
   @Id
   public int id;

   public String name;

   @ManyToOne(cascade = {CascadeType.DETACH} )
   Category category

   @ManyToMany(fetch = FetchType.EAGER, cascade = {CascadeType.DETACH} )
   Set<Category> secondaryCategories;


}

and this entity:

@Entity
public Category {
   @Id
   public int id;

   public String name;
}

I would like to be able to send a POST with json

{ name: "name", category: 2, secondaryCategories: [3,4,5] } from client-side

and be able to be deserialized like:

{ name: "name", category: {id: 2 }, secondaryCategories: [{id: 3}, {id: 4}, {id: 5}] }

in case it was sent as

 { name: "name", category: {id: 2 }, secondaryCategories: [{id: 3}, {id: 4}, {id: 5}] }

I would like it to still work as now

what kind of annotation and custom deserializer I need? Hopefully the deserializer can work for all possible objects that have id as a property

Thanks!

Edit

• See the preferred zafrost's @JsonCreator answer (https://stackoverflow.com/a/46618366/986160)
• See my complete answer (https://stackoverflow.com/a/46618193/986160) for extending StdDeserializer and using default deserialization through ObjectMapper

Answer 1

Another approach is to use @JsonCreator factory method if you can modify your Entity

private class Product {
    @JsonProperty("category")
    private Category category;

    @JsonProperty("secondaryCategories")
    private List<Category> secondaryCategories;
}


private class Category {
    @JsonProperty("id")
    private int id;

    @JsonCreator
    public static Category factory(int id){
        Category p = new Category();
        p.id = id;
        // or some db call 
        return p;
    }
}

Or even something like this should also work

private class Category {
    private int id;

    public Category() {}

    @JsonCreator
    public Category(int id) {
        this.id = id;
    }
}