How to Map a Table to an Object Attribute? - spring

Question

I have a device with many identical sensors, so I need to mapping as much Entities Attributes as needed, instead of designing a table to each sensor.
How can I do that in Spring Boot?
Like:
#Entity
#Table(name = "device")
public class Devide {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Table(name = "sensor")
private Sensor sensor1; // This is my conceptual problem
#Table(name = "sensor")
private Sensor sensor2; // This is my conceptual problem
.
.
.

Answer 1

As your one Device can have many sensors and one Sensor can be part of may devices, you have to create ManyToMany relation between Sensors and Devices. You can refer the following mapping
#Entity
#Table(name = "Device")
public class Device {
// ...
#ManyToMany(cascade = { CascadeType.ALL })
#JoinTable(
name = "Device_Sensor",
joinColumns = { #JoinColumn(name = "Device_id") },
inverseJoinColumns = { #JoinColumn(name = "Sensor_id") }
)
Set<Sensor> Sensors = new HashSet<>();
// standard constructor/getters/setters
}
#Entity
#Table(name = "Sensor")
public class Sensor {
// ...
#ManyToMany(mappedBy = "Sensors")
private Set<Device> Devices = new HashSet<>();
// standard constructors/getters/setters
}
Device_Sensor will act as a link between other two tables.