By utilizing Jackson's Mix-in feature, I successfully managed to solve this problem. This particular feature allows you to specify JSON annotations on classes, fields, and getter/setter methods which are then applied to the bean or POJO you serialize. Essentially, a mix-in enables the addition of annotations at runtime without the need to modify the source file of the bean/POJO. To implement this, Jackson's module feature is used to apply a Mixin dynamically during runtime.
In my approach, I created one mix-in that adds the @JsonIgnore annotation to the 'getVendas' getter method of the 'UserAccount' class, and another mix-in that applies the @JsonIgnore annotation to the 'cliente' getter method of the 'Venda' class.
Below is the updated 'UserAccount' class:
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
public class UserAccount implements Serializable
{
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private List<Venda> vendas = new ArrayList<>();
public Long getId() { return id; }
public void setId(Long id) { this.id = id; }
public List<Venda> getVendas() { return vendas; }
public void setVendas(List<Venda> vendas) { this.vendas = vendas; }
public void addVenda(Venda v) {
this.vendas.add(v);
v.setCliente(this);
}
// FilterVendas - Jackson mixin adding @JsonIgnore to 'getVendas' method
public static class FilterVendas extends SimpleModule {
@Override
public void setupModule(SetupContext context) {
context.setMixInAnnotations(UserAccount.class, FilterVendas.class);
}
@JsonIgnore
public List<Venda> getVendas() { return null; }
}
Here is the modified 'Venda' class:
public class Venda implements Serializable
{
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
private UserAccount cliente;
public Long getId() { return id; }
public void setId(Long id) { this.id = id; }
public UserAccount getCliente() { return cliente; }
public void setCliente(UserAccount cliente) { this.cliente = cliente; }
// FilterCliente - Jackson mixin adding @JsonIgnore to 'getCliente' method
public static class FilterCliente extends SimpleModule {
@Override
public void setupModule(SetupContext context) {
context.setMixInAnnotations(Venda.class, FilterCliente.class);
}
@JsonIgnore
public UserAccount getCliente() { return null; }
}
}
Finally, here is the test method with runtime object mapper configuration:
public static void main(String... args) {
Venda v = new Venda();
UserAccount ua = new UserAccount();
v.setId(1L);
ua.setId(1L);
ua.addVenda(v);
try {
ObjectMapper mapper = new ObjectMapper();
System.out.println("UserAccount: (unfiltered)");
System.out.println(mapper.writeValueAsString(ua));
mapper = new ObjectMapper();
mapper.registerModule(new Venda.FilterCliente());
System.out.println("UserAccount: (filtered)");
System.out.println(mapper.writeValueAsString(ua));
mapper = new ObjectMapper();
System.out.println("Venda: (unfiltered)");
System.out.println(mapper.writeValueAsString(v));
mapper = new ObjectMapper();
mapper.registerModule(new UserAccount.FilterVendas());
System.out.println("Venda: (filtered)");
System.out.println(mapper.writeValueAsString(ua));
} catch (Exception e) {
e.printStackTrace();
}
}
Output:
UserAccount: (unfiltered)
{"id":1,"vendas":[{"id":1,"cliente":1}]}
UserAccount: (filtered)
{"id":1,"vendas":[{"id":1}]}
Venda: (unfiltered)
{"id":1,"cliente":{"id":1,"vendas":[{"id":1,"cliente":1}]}}
Venda: (filtered)
{"id":1}