How can I create Join table in MySQL database using hibernate in Java? - mysql

Question

I have two entity table called appointment and service. One appointment can be many services. Services already store in the database. We can newly add appointment. When add new appointment we selected added services from the drop down menu. Can add many services with one appointment. I need to store new record on appointment table and store relevant appointment id and services id's on another join table. Here attached image with my problem.
Already I tried many ways for do this. Bellow is one attempt.
Here is appointment class
#Entity
#Table(name="appointment")
public class Appointment extends AbstractPersistable<Long> implements Serializable {
#OneToMany
#JoinTable(name = "service_x_appointment", joinColumns = #JoinColumn(name = "appointment_id"),
inverseJoinColumns = #JoinColumn(name = "beautyservice_id"))
Set<BeautyService> beautyServices;
private String type;
private Date date;
private String time;
private String description;
private int approval;
#ManyToOne
#JoinColumn(name = "userid")
private User user;
//getter and setter
}
Here is BeautyService class
#Entity
#Table(name="beauty_service")
public class BeautyService extends AbstractPersistable<Long> {
private String serviceName;
private String timeDuration;
private String amount;
//getter and setter
}
Here is appointment controller class code,
#RequestMapping(value="/createAppointment",method = RequestMethod.POST)
public String createAppointment(#RequestBody Appointment appointment){
String response = null;
response = appointmentService.save(appointment);
return response;
}
Here is appointment service class code
public String save(Appointment appointment) {
appoinmentRepository.save(appointment);
return "Appointment added successfully";
}
Here is the my request body.
{
"type":"Type02",
"date":null,
"time":"20:56",
"description":"Hellow World",
"approval":0,
"user":{
"id":2,
"name" : "Alex",
"telephone" : "0774466886",
"age":21,
"email": null
},
"beautyServices" : [
{
"id":1,
"serviceName":"hair strate",
"timeDuration" : "02 Hours",
"amount" : 5000
},
{
"id":2,
"serviceName":"Eye brows",
"timeDuration" : "02 Hours",
"amount" : 5000
},
{
"id":3,
"serviceName":"Near cutting",
"timeDuration" : "02 Hours",
"amount" : 5000
}
]
}
Why not record in the join table? Only appointment table.

Answer 1

You can do it in multiple ways. One has been specified #Aritra Paul, which is actually Bidirectional representation of OneToMany mapping.
I think you want to use UniDirectional representation. In that case you won't have to use mappedBy.
Just create your entities like below:
#Entity
#Table(name="appointment", schema="ADMIN")
public class Appointment implements Serializable {
#OneToMany
#JoinColumn(name = "appointment_id")
#JoinTable(name = "service_appointment", joinColumns = #JoinColumn(name = "appointment_id"),
inverseJoinColumns = #JoinColumn(name = "service_id"))
Set<Service> services;
}
#Entity
public class Service {
// Some Properties. No need to specify reference of Appointment here.
}
If you define your entities like that you will have a join table like this
+----------------+------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------------+------------+------+-----+---------+-------+
| appointment_id | bigint(20) | NO | MUL | NULL | |
| service_id | bigint(20) | NO | PRI | NULL | |
+----------------+------------+------+-----+---------+-------+
Hope this helps!!

Answer 2

You definitely shouldn't create Joined table entity as you mentioned as it's more the underlying database representation than the object oriented one.
You can achieve the join table by defining something like:
#Entity
#Table(name="appointment", schema="ADMIN")
public class Appointment implements Serializable {
//...
#OneToMany(mappedBy="appointment")
#JoinTable(name="Join_Table")
Set <ServiceT> service;
use relation mapping ManyToOne or OneToMany according to your table.
#Entity
#Table(name="service", schema="ADMIN")
public class ServiceT implements Serializable {
//...
#ManyToOne
Appointment appointment;
If you want to explicitely set your column name you can use
#JoinColumn
annotation.

Answer 3

Can you please check if the beautyServices are actually being bound from the #RequestBody properly.
The property name is beautyServices while in Json it says "service".
In the Json it should say "beautyServices" instead of "service".
Also, check if the ids 1, 2, 3 already pre-exists on the beautyServices table.
If Not, if you want those to get inserted as well by saving appointment, you need to add CASCADETYPE.PERSIST.