I have a spring boot application with database and entity with #Transcient field... here you have a sample code:
#Entity
#Table(name = "dogs")
#JsonInclude(Include.NON_NULL)
#ApiModel
public class Dog {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#Transient
public Boolean happy;
}
Dog dog1 = dogsRepository.findById(1);
dog1.setHappy(true);
Dog dog2 = dogsRepository.findById(1);
System.out.println("dog2 is happy = " + dog2.isHappy());
and the last line prints dog2 is happy = true on the screen. How it is possible? #Transient fields are not persisting in a database.
The method dogsRepository.findById checks the 1st level cache. If it cannot be found there it will be fetched from the database and stored in the 1st level cache. That is why the 2nd call to findById will not retrieve it from the database but from the cache instead. That is why dog1 and dog2 are the same object in your case.
That will not happen for example if you clear the cache between the findById calls or execute the calls in different transactions.
Related
I am using a entity class for mixing two/three table columns in one entity to hold an outcome of SYS_REFCURSOR in oracle
This allows me to have single class which is not mapped to any table but it still is an Entity
#Data
#Entity
#NoArgsConstructor
class EmployeeDetails {
#Id
#Column("emp_id")
String empId;
#Column("job_name")
String jobName;
#Column("dept_name")
String deptName;
//Future requirement
//String updatedBy
}
Now I have an additional requirement, to add who last modified the employee table, I don't want modify the procedure now, the procedure is being re-used in another background procedure and batch jobs.
My question is, is it possible to use #ManyToOne on this class which is obviously not mapped to any table
If not how do avoid manually looping a child array list, is there a ready made option in JPA or spring boot to achieve that.
Or what will be the smartest/recommended way to bring the below Entity into this class
#Data
#Entity
#NoArgsConstructor
#Table(name="app_users")
class AppUsers {
#Id
#Column(name="user_id")
String userId;
#Column
String userName;
}
#Transient, check how this annotation works it will resolve the issue, you need to understand working of #Transient
My spring boot 2.6.2 EntityManager code is as follows
q = em.createStoredProcedureQuery("MY_PROC",EmployeeDetails.class);
q.registerStoredProcedureParameter("OUT_REFC", void.class, ParameterMode.REF_CURSOR);
q.execute();
q.getResultList()
I have modified my class EmployeeDetails as below
#Data
#Entity
#NoArgsConstructor
class EmployeeDetails {
#Id
#Column("emp_id")
String empId;
#Column("job_name")
String jobName;
#Column("dept_name")
String deptName;
#OneToOne
#JoinColumn(
name="user_id",
referencedColumnName="emp_id",
insertable=false,
updatable=false,
nullable=true
)
AppUsers updatedBy;
}
The log prints Hibernate two times one after one as below, first it calls the proc and then it calls the select query, so, I did not wrote that SQL myself, the JPA layer is taking care of it
Hibernate:
{call MY_PROC(?)}
Hibernate:
select
...
...
from app_users
where user_id=?
so, my expectation achieved and I am getting the values
i'm using Spring Boot 2.4.2 and Data module for JPA implementation.
Now, i'm using an Oracle View, mapped by this JPA Entity:
#Entity
#Immutable
#Table(name = "ORDER_EXPORT_V")
#ToString
#Data
#NoArgsConstructor
#EqualsAndHashCode(onlyExplicitlyIncluded = true)
public class OrderExportView implements Serializable {
private static final long serialVersionUID = -4417678438840201704L;
#Id
#Column(name = "ID", nullable = false)
#EqualsAndHashCode.Include
private Long id;
....
The view uses an UNION which allows me to obtain two different attributes of the same parent entity, so for one same parent entity (A) with this UNION I get the attribute B in row 1 and attribute C in row 2: this means that the rows will be different from each other.
If I run the query with an Oracle client, I get the result set I expect: same parent entity with 2 different rows containing the different attributes.
Now the issue: when I run the query with Spring Data (JPA), I get the wrong result set: two lines but duplicate.
In debug, I check the query that perform Spring Data and it's correct; if I run the same query, the result set is correct, but from Java/Spring Data not. Why??
Thanks for your support!
I got it! I was wrong in the ID field.
The two rows have the same parent id, which is not good for JPA, which instead expects a unique value for each line.
So, now I introduced a UUID field into the view:
sys_guid() AS uuid
and in JPA Entity:
#Id
#Column(name = "UUID", nullable = false)
#EqualsAndHashCode.Include
private UUID uuid;
#Column(name = "ID")
private Long id;
and now everything works fine, as the new field has a unique value for each row.
I see in most of the coders save data(using spring data) as:
savedEntity = repo.save(savedEntity);
Long id = savedEntity.getId();
I am confused about why most of them assign back the returned value to the saved Entity while the following code also works exact(I have tested myself):
repo.save(savedEntity);
Long id = savedEntity.getId();
Did I miss some benefit of assigning back?
for example, let the entity be:
#Entity
public class SavedEntity {
#Id
private int id;
private String name;
//getter, setters, all arg-constructor, and no-arg constructor
}
Consider the object of SavedEntity is
SavedEntity entity = new SavedEntity(1,"abcd");
now for your first question,
SavedUser entity1 = repo.save(entity);
Long id = entity1.getId();
this entity1 object is the return object getting from the database, which means the above entity is saved in the database succesfully.
for the Second Question,
repo.save(entity);
Long id = entity.getId();//which you got it from SavedEntity entity = new SavedEntity(1,"abcd");
here the value of id is the integer you mentioned in place of id(the raw value).
Most of the time the id (primary key) is generated automatically while storing the entity to the database using strategies like AUTO, Sequence etc. So as to fetch those id's or autogenerated primary key values we assign back the saved entity.
For example:
#Entity
public class Customer {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
private Long id;
private String firstName;
private String lastName;
}
In this case you'll not pass the id externally but it will create a value for it automatically while storing the data to DB.
I get an Post request that would give me a List<PersonApi> Objects
class PersonApi {
private String name;
private String age;
private String pincode ;
}
And I have an Entity Object named Person
#Entity
#Table(name = "person_master")
public class Person{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
Long id;
#Column(name = "name")
String name;
#Column(name = "age")
String age;
#Column(name = "pincode ")
String pincode ;
}
My record from Post request would look something like this (pseudocode representation of the data below)
[
"Arun","33","09876gh"
"James","34","8765468"
]
I need to do a bulk-validation using Spring JPA.. Give the List<PersonApi> and get a True or False based on the condition that all the entries in the PersonApi objects list should be there in the database.
How to do this ?
The selected answer is not a right one. (not always right)
You are selecting the whole database to check for existence. Unless your use case is very special, i.e. table is very small, this will kill the performance.
The proper way may start from issuing repository.existsById(id) for each Person, if you never delete the persons, you can even apply some caching on top of it.
exists
Pseudo Code:
List<PersonApi> personsApiList = ...; //from request
List<Person> result = personRepository.findAll();
in your service class you can access your repository to fetch all database entities and check if your list of personapi's is completeley available.
boolean allEntriesExist = result.stream().allMatch(person -> personsApiList.contains(createPersonApiFromPerson(person)));
public PersonApi createPersonApiFromPerson(Person person){
return new PersonApi(person.getName(), person.getAge(), person.getPincode());
}
I am trying to find a way to retrieve the auto generated Id of an entity that is persisted in the database via cascade. I am using Hibernate 4.1.9, Spring data 1.2 and Spring framework 3.2.1. Here are the entities in question : Location, Home, Room.
Location parent class
#Entity
#Table(name = "location")
#Inheritance(strategy = InheritanceType.JOINED)
public class Location implements Serializable
{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "location_id", unique = true)
private long uuid;
// other attributes and methods not relevant
}
Home class extending a Location, referencing a set of Rooms
#Entity
#Table(name = "home")
#Inheritance(strategy = InheritanceType.JOINED)
#PrimaryKeyJoinColumn(name = "home_id")
public class Home extends Location implements Serializable
{
#OneToMany(mappedBy = "containingHome", cascade = {CascadeType.ALL}, orphanRemoval = true)
private Set<Room> rooms;
// other attributes and methods not relevant
}
and finally the Room class referencing a Home object
#Entity
#Table(name = "room")
#PrimaryKeyJoinColumn(name = "room_id")
public class Room extends Location implements Serializable
{
#ManyToOne()
#JoinColumn(name = "home_id")
protected Home containingHome;
// other attributes and methods not relevant
}
I am using Spring data to create Repositories for the entities.
LocationRepository
public interface LocationRepository extends JpaRepository<Location, Long>
{ }
The problem I am having is that I need the id in order to be able to retrieve the different objects from the database and that is generated automatically. The only way I can access the id through the element is if I get the managed object when I save it to the database. But if I try to save each location in turn like so:
Home home = new Home();
home = locationService.save(home) // service that just calls locationRepository.save method
Room bedroom = new Room(home);
bedroom = locationService.save(bedroom);
I get a duplicate entry of room in the database which I think is related to a Hibernate issue https://hibernate.onjira.com/browse/HHH-7404. If I just call
Home home = new Home();
Room bedroom = new Room(home);
locationService.save(home)
there are no doubles but I have no way to retrieve the room object since it was persisted on cascade and its id is 0. Is there a way to solve this without introducing other fields in the location like a unique name that I have to generate myself? Any help is much appreciated.
Edit
If in the last case I have home = locationService.save(home) and then call home.getUuid() I get the right value which is normal I think since I retrieve a managed object. But if I do bedroom.getUuid() I get 0 since bedroom is not managed and so it has not had its id field updated with the value from the database.
Have you tried calling home.getUuid(); (assuming you have a getter for that field) after the persist call?
You might be surprised, but Hibernate (and JPA) will update the in memory copy with the id.