How to prevent saving of referred entity when using #IdClass? - spring

Question

I have two entities, Type and TypeValue. Each Type can have several TypeValues. While trying to persist a new TypeValue, I get a database error that Type already exists (which is correct, but I don't want to add it again, I want to add just a new 'TypeValue'). I have similar classes without IdClass that are working, so I assume that either the #IdClass definition is wrong or I forgot to define something so that the referred object is not updated.
How to prevent saving of the referred entity Type when using #IdClass for TypeValue?
Class definitions:
#Entity
#Table(name = "TYPE", schema = "VOC")
public class Type implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#Column(name = "TYPEID")
private String typeID;
#Column(name = "NAME")
private String name;
#OneToMany(mappedBy = "type")
private List<TypeValue> listTypeValue;
// constructor, getter, setter, equals, hashcode, ...
}
#Entity
#IdClass(TypeValueID.class)
#Table(name = "TYPE_VALUE", schema = "VOC")
public class TypeValue implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#ManyToOne
#JoinColumn(name = "TYPEID")
#ForeignKey(name = "TYPEVALUE_FK")
private Type type;
#Id
#Column(name = "VALUE")
private String value;
// constructor, getter, setter, equals, hashcode, ...
}
public class TypeValueID implements Serializable {
private static final long serialVersionUID = 1L;
String type;
String value;
// equals, hashcode
}
Example of usage:
Type type = ... // get existing type with typeID "DETAIL"
Session session = sessionFactory.getCurrentSession();
TypeValue newTypeValue = new TypeValue(type, "new value");
session.save(newTypeValue);
session.flush();
Thrown exception:
SEVERE: Servlet.service() for servlet [spring] in context with path [/project] threw exception [Request processing failed; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement] with root cause
org.postgresql.util.PSQLException: ERROR: duplicate key value violates unique constraint "type_pkey"
Detail: Key (typeid)=(DETAIL) already exists.
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2455)
at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:2155)
...

Answer 1

please change your String typeID to int or long. Then use #GeneratedValue for auto-increment.
#Id
#GeneratedValue(strategy= GenerationType.AUTO)
private int typeID ;
Check this example
#Entity
#Table(name = "USERS")
#Proxy(lazy = false)
public class User {
#Id
#GeneratedValue(strategy= GenerationType.AUTO)
private int uID ;
private String uName ;
private String uEmail ;
private String uPassword;
#OneToMany(cascade=CascadeType.ALL,fetch = FetchType.EAGER)
private List<Reminder> uReminders = new ArrayList<>();
Next Entity
#Entity
#Proxy(lazy = false)
public class Reminder {
#Id
#GeneratedValue(strategy= GenerationType.AUTO)
private int reminderID ;
private Date reminderDate ;
private String reminderDescription ;

Answer 2

You have defined the foreign key column with #Id.
#Id
#ManyToOne
#JoinColumn(name = "TYPEID")
#ForeignKey(name = "TYPEVALUE_FK")
private Type type;
So it is expecting unique value in the column "type".Hope this may help.

Answer 3

The type attribute in the TypeValueID class is wrong, the class should look like this:
public class TypeValueID implements Serializable {
private static final long serialVersionUID = 1L;
Type type;
String value;
// equals, hashcode
}
The JPA Persistence API 2.1 documentation states:
The names of the fields or properties in the primary key class and the
primary key fields or properties of the entity must correspond and
their types must match according to the rules specified in Section
2.4, “Primary Keys and Entity Identity” and Section 2.4.1, “Primary Keys Corresponding to Derived Identities”.
And the rule that applies in this case is:
If the composite primary key class is represented as an id class, the
names of primary key fields or properties in the primary key class and
those of the entity class to which the id class is mapped must
correspond and their types must be the same.