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Spring Data JPA save() return entity

I am using spring boot data jpa as below
#Entity
#Table(name = "invoice")
#Getter
#Setter
#ToString
public class Invoice {
#Id
#Column(name = "inv_id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private BigInteger invId;
#Column(name = "external_id")
private String externalInvoiceId;
#Column(name = "amount")
private double amount;
#JsonIgnore
#JsonIgnoreProperties
#Column(name = "status")
private int status;
#JsonProperty("status")
#Transient
private String invoiceStatus;
public String getInvoiceStatus() {
switch (this.status){
case 1:
return "INITIATED";
case 2:
return "CANCELLED";
case 3:
return "SUCCESS";
case 4:
return "FAILURE";
default:
return "IN PROGRESS";
}
}
#CreationTimestamp
#Temporal(TemporalType.TIMESTAMP)
#Column(name = "created_at")
private Date createdAt;
#UpdateTimestamp
#Temporal(TemporalType.TIMESTAMP)
#Column(name = "updated_at")
private Date updatedAt;
#PostPersist
public void updateExternalID() {
this.externalInvoiceId="G".concat(String.valueOf(this.invId.multiply(BigInteger.valueOf(1000))))
.concat(String.valueOf(Instant.now().getEpochSecond()));
}
}
Am accesing this entiry via repository as below
public interface InvoicesRepository extends JpaRepository<Invoice, BigInteger> {
}
At my #Service am performing the below operation
#Autowired
private InvoicesRepository myInvoicesRepository;
Invoice transactionInvoice = new Invoice();
transactionInvoice.setAmount(200.0);
transactionInvoice.setStatus(1);
Invoice savedInvoice = myInvoicesRepository.save(transactionInvoice);
Am using savedInvoice and trying to update the status. Either it is not updating the status properly nor I could not find the record in database too.
There are no rollback present
Below are the logs I could see insert statements are present
[XNIO-1 task-1] DEBUG org.hibernate.SQL.logStatement -
/* insert com.min.app.model.Invoice
*/ insert
into
invoice
(amount, created_at, external_inv_id, status, updated_at)
values
(?, ?, ?, ?, ?)
Hibernate:
/* insert com.min.app.model.Invoice
*/ insert
into
invoice
(amount, created_at, external_inv_id, status, updated_at)
values
(?, ?, ?, ?, ?)
After the status updates I tried printing the savedInvoice could see the below in logs
Invoice(invId=58, externalInvoiceId=G580001575271905, amount=185.0 status=4, invoiceStatus=FAILURE, createdAt=Mon Dec 02 13:01:45 IST 2019, updatedAt=Mon Dec 02 13:01:45 IST 2019)
The above record I could not see in the table.
What am I doing wrong?

you need to perform transactions in a function call as follows and put your #Autowired repository in Global level ass follows.
class whatever{
#Autowired
private InvoicesRepository myInvoicesRepository;
//call this function
void doSomething(){
Invoice transactionInvoice = new Invoice();
transactionInvoice.setAmount(200.0);
transactionInvoice.setStatus(1);
Invoice savedInvoice = myInvoicesRepository.save(transactionInvoice);
}
}

how to find the data by an attribute (name_techno) in jpql

I am developing an application that allows managing candidates in a company, for that I use spring-boot, in order to select the employees who master such a technology (Techno) I used a request JPQL.
So, How can I find a candidate by techno?
In my project I used this code:
1 - the class candidat.java
#Entity
public class Candidat {
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(name = "candidat_id")
private int id;
private String nom;
private String prenom;
private String ville;
private int numTel;
private String mail;
private String pseudo;
private String roleCible;
private String typeContrat;
private String villeRecherchee;
#OneToMany(mappedBy="candidat")
private List<Techno> techno;
#Temporal(TemporalType.DATE)
private Date date;
#OneToMany
private List<SecteurActivites> secteurActivites;
public Candidat() {
// TODO Auto-generated constructor stub
}
2- the class Techno.java
#Entity
public class Techno {
#Id
#GeneratedValue
#Column(name = "techno_id")
private int id ;
private String nomTechno;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "candidat_id", nullable = false)
#OnDelete(action = OnDeleteAction.CASCADE)
#JsonIgnore
private Candidat candidat;
public Techno() {
// TODO Auto-generated constructor stub
}
/**
* #param nomTechno
* #param candidat
*/
public Techno(String nomTechno, Candidat candidat) {
super();
this.nomTechno = nomTechno;
this.candidat = candidat;
}
3- My CandidatController
#GetMapping(value = "/GetAllCandidats/{nomTechno}")
public List<Candidat> afficherCandidat(#PathVariable ("nomTechno") String nomTechno){
return candidatdao.findByTechno(nomTechno);
}
4- the repository:
#Repository
public interface CandidatDao extends JpaRepository <Candidat, String>{
List<Candidat> findByDate(Date date);
#Query("SELECT DISTINCT e FROM Candidat e INNER JOIN e.Techno t")
List<Candidat> findByTechno(String nomTechno);
}
5- app.properties
server.port= 9090
spring.jpa.show-sql = true
spring.datasource.url= jdbc:mysql://localhost:3306/database
spring.datasource.username=??
spring.datasource.password=??
spring.jpa.hibernate.ddl-auto=update
The result in console is:
"Validation failed for query for method public abstract java.util.List com.avatar.dao.CandidatDao.findByTechno(java.lang.String)!"

You can declare the following method into your JpaRepository (also remove the #Query, it is not needed).
List<Candidat> findDistinctByTechnoNomTechno(String nomTechno);
Also in Techno.java you should add the #Column annotation and map it with the DB schema.
I am not sure if you have pasted incomplete code of your entities on purpose. If not your entities are not correct. You should create setters/getters as the following
private String nomTechno;
#Column(name = "NOM_TECHNO")
public String getNomTechno() {
return nomTechno;
}
public void setNomTechno(String nomTechno){
this.nomTechno = nomTechno;
}
Do the above for all variables in your entities.

You do not need to add explicit #Query for this, Spring data can formulate a query if you have right method names
Instead of
#Query("SELECT DISTINCT e FROM Candidat e INNER JOIN e.Techno t")
List<Candidat> findByTechno(String nomTechno);
Try this
List<Candidat> findDistinctByTechno_NomTechno(String nomTechno);

How to depict joins with #Query annotation in Spring JPA Repository method

I am using Spring-Boot with JPA and a MySQL backend. Now I got quite confused about the repositories Spring-Boot provides. I know these are quite powerful (and seem to be quite useful since they can shorten your code a lot). Still, I do not understand how to represent Joins within them, since the result-set should be a combination of specified attributes in the select of a few Entities.
Now let's assume we have three tables Book, Author, AuthorOfBook, where the last one is simply connecting Book and Author by a combined Primary key. I guess we had the following Java-Classes:
Entity Book:
#Entity
#Table(name="BOOK")
public class Book {
#Id #GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "ID")
private int id;
#Column(name = "TITLE")
private String title;
}
Entity Author
#Entity
#Table(name="AUTHOR")
public class Author {
#Id #GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "ID")
private int id;
#Column(name = "LASTNAME")
private String lastname;
#Column(name = "FIRSTNAME")
private String firstname;
//Let's assume some getters and setters and a constructor
}
Entity AuthorOfBook:
#Entity
#Table(name="BOOK")
public class Book {
#EmbeddedId
private AuthorOfBookId pk;
}
An Embedded ID
#Embeddable
public class AuthorOfBookId implements Serializable {
private int authorId;
private int bookId;
}
Repository
#Repository
public interface AuthorOfBookRepository extends JpaRepository<,AuthorOfBookId> {
}
Now how would I represent that query:
SELECT b.name, a.firstname, a.lastname from AuthorOfBook ab inner join Book b on b.id = ab.book_id inner join Author a on a.id = ab.author_id where a.lastname = :lastname;
in my repository? I know the signature would need to be like
#Query([the query string from above])
public (...) findAuthorAndBookByAuthorLastname(#Param("lastname") String lastname);
but I cannot make out what Type the return would be like. What is that method returning? (simply AuthorOfBook would not work I guess)

You don't want AuthorOfBook as a separate Entity. Book should have a field of type Author as a #ManyToOne relationship. That way, given any Book, you can find the author's details.

If you want to handle audits fields you can do something like this:
Audit class
#Embeddable
public class Audit {
#Column(name = "created_on")
private Timestamp createdOn;
#Column(name = "updated_on")
private Timestamp updatedOn;
#Column(name = "is_deleted")
private Boolean isDeleted;
//getters and setters
}
AuditListener to update automatically audits fields
public class AuditListener {
private Long loggedUser = 1001L;
/**
* Method to set the fields createdOn, and isDeleted when an entity is persisted
* #param auditable
*/
#PrePersist
public void setCreatedOn(Auditable auditable) {
Audit audit = auditable.getAudit();
if (audit == null) {
audit = new Audit();
auditable.setAudit(audit);
}
audit.setIsDeleted(Boolean.FALSE);
audit.setCreatedOn(Timestamp.from(Instant.now()));
}
/**
* Method to set the fields updatedOn and updatedBy when an entity is updated
* #param auditable
*/
#PreUpdate
public void setUpdatedOn(Auditable auditable) {
Audit audit = auditable.getAudit();
audit.setUpdatedOn(Timestamp.from(Instant.now()));
}
}
And add this to the entities
#EntityListeners(AuditListener.class)
public class Book implements Auditable {
#Embedded
private Audit audit;

Hibernate querying on a parent class creates ineffective union query

I am using spring boot and hibernate and I have following data structure.
#Entity
public class Template {
#Id
private Integer id;
#OneToMany(mappedBy = "template", orphanRemoval = true, fetch = FetchType.EAGER,cascade = CascadeType.ALL)
#BatchSize(size = 30)
private Collection<TemplateContent> contents;
}
#Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public abstract class TemplateContent {
#Id
private String contentType;
#Id
#ManyToOne(fetch = FetchType.EAGER, optional = false)
#JoinColumn(name = "template_id", nullable = false)
private Template template;
}
#Entity
public class SomeContent extends TemplateContent {
private String someValue;
}
#Entity
public class SomeOtherContent extends TemplateContent {
private String someOtherValue;
}
#Repository
public interface TemplateRepository extends JpaRepository<Template, Integer> {
Page<Template> findByIdIn(Collection<Integer> ids, Pageable pageable);
}
When I call findByIdIn method it generates the following query:
SELECT ...
FROM (SELECT content_type,
template_id,
some_value,
NULL AS some_other_value
FROM someContent
UNION
SELECT content_type,
template_id,
some_other_value,
NULL AS some_value
FROM someOtherContent) contents0_
WHERE contents0_.template_id IN ( ?, ?, ? )
which is ineffective, because MySQL can't use indexes over derived tables. Is there a way to generate a more effective query.
//this would be the desired query
SELECT ...
FROM (SELECT content_type,
template_id,
some_value,
NULL AS some_other_value
FROM someContent
WHERE template_id IN ( ?, ?, ? )
UNION
SELECT content_type,
template_id,
some_other_value,
NULL AS some_value
FROM someOtherContent
WHERE template_id IN ( ?, ?, ? )) contents_0_ ....
I tried also to use different inheritance strategies, but it seems like all of them have a similar drawback.

If you want to have best performance in polymorphic query the best approach is to use strategy = InheritanceType.SINGLE_TABLE, probably you will pay performance with empty columns, but it depends which aspect is more important for you, also because strategy = InheritanceType.JOINED has same problems of TABLE_PER_CLASS

JPA Join table with SELECT

I have a SQL query like this:
SELECT h.name, h.created_date, tbl.*
FROM my_table tbl
LEFT JOIN
(SELECT name, max(created_date) created_date FROM my_table GROUP BY name) h
ON tbl.name = h.name;
It returns the row from my_table (which has multiple for name="") along with the maximum created_date for that name.
Is there a way to replicate this in a JPQL query?
Here is the gist of the Entity class, it's quite simple:
#Entity
#Table(name = "MY_TABLE")
#XmlRootElement
public class MyTable implements Serializable {
private BigDecimal tableId;
private String name;
private Date createdDate;
// ...
#Id
#Basic(optional = false)
#Column(name = "TABLE_ID")
#GeneratedValue(generator = "TBL_ID_SEQ")
public BigDecimal getTableId() {
return tableId;
}
#Basic(optional = false)
#Column(name = "NAME")
public String getName() {
return name;
}
#Basic(optional = false)
#Column(name = "CREATED_DATE", insertable = false)
#Temporal(TemporalType.TIMESTAMP)
public Date getCreatedDate() {
return createdDate;
}
// ... getters/setters
}

Just reading your question I guess you do not need another entity. Entities in JPA are the same like tables in SQL. Usually there is a 1:1 relationship between entities and tables. You just have to know how to invoke a query using JPQ. You need a entity manager, which invokes your statement.
EntityManagerFactory emf = Persistence.createEntityManagerFactory("PersistenceUnit");
EntityManager em = emf.createEntityManager();
You have to define your persistence unit, i.e. in a pom file, or a config java file. So done you can go on coding something like this:
Query q = em.createQuery( "Your query in sql syntax as a string object" );
In respect to your entities and invoked query you will receive a List using
List<object> resultOfMyQuery = q.getResultList();
This is only one short example. But hopefully you got some buzzwords to look for ;)