CRUD在休眠状态下从ManyToMany中使用Jersey使用Java的REST API在REST API中使用POST方法读取JSON的问题

Question

So, my problem goes like this: I created a RESTfull web service in Java using Jersey. Also, to map and use the MySQL database, I used hibernate (jpa). I have a POJO named "horarios". Also, a POJO named "turmas". They are refered to each other using a @ManyToMany notaion in Hibernate. They go as this:

Turmas.java

@Entity
public class Turmas {

@Id  
@GeneratedValue
@Column(name = "turmas_id", unique = true, nullable = false)
int Id;
@Column
String codigo;

@ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL)
@JoinTable(name = "turmas_horarios", joinColumns = {
        @JoinColumn(name = "turmas_id", nullable = false, updatable = false)     },
        inverseJoinColumns = { @JoinColumn(name = "horarios_id",nullable =     false, updatable = false) })
private List<horarios> Horarios;
}
//... getters and setters

Horarios.java

@Entity
public class horarios {

@Id
@GeneratedValue
@Column(name = "horarios_id", nullable = false, unique = true)
int Id;

@ManyToMany(fetch = FetchType.EAGER, mappedBy = "Horarios")
private List<Turmas> turmas;

@Column
private int horario;

@Column
private int dia;
//...getters and setters

}

And here goes the HorariosController:

@Path("/horarios")
public class HorariosController {

@Path("/setHorarios")
@POST
@Consumes(MediaType.APPLICATION_JSON)
public Response setHorarios(horarios h) throws Exception
{
    horarios h1 = new horarios();
    h1.setDia(h.getDia());
    h1.setHorario(h.getHorario());
    h1.setTurmas(h.getTurmas());
    Querys.Persist(h1);
    return Response.status(200).build();
}

}   

//...GET and DELETE methods

The problem goes like this: For every column, it is very easy to treat the json object. But I really can't do it using a many to many type.. here goes an example of a json I'm sending:

{"dia": 6,"horario": 15,"turmas": {"codigo":"xxxx"}}

Which is valid according to http://www.jsonlint.com/ . Though, when I try the POST method, it gives me the return:

Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
 at [Source: org.glassfish.jersey.message.internal.ReaderInterceptorExecutor$UnCloseableInputStream@1b23d8c; line: 3, column: 15] (through reference chain: modules.horarios["turmas"])

And for that reason I can't extract the value I put in the Turmas' fields.

The final question is : How (and what do I have to change) to read the JSON file and put in the Join Column the relationship between a passed Turmas and Horarios? Like how can I read the turmas' passed Id (for example) without getting that error?

Answer 1

you have to change your json like below. As per your horaio entity definition your horario should have list of turmas. {"dia": 6,"horario": 15,"turmas": [{"codigo":"xxxx"}]}