I use play framework !! But when I run my project it give me this
org.hibernate.exception.SQLGrammarException: could not execute query
who can help me ?
this is my model:
package models;
import java.util.*;
import javax.persistence.*;
import play.db.jpa.*;
import play.db.jpa.Model;
#Entity
#Table(name="GxkAccount")
public class GxkAccount extends Model {
private String Account;
private String Psw;
public String getAccount() {
return Account;
}
public void setAccount(String account) {
Account = account;
}
public String getPsw() {
return Psw;
}
public void setPsw(String psw) {
Psw = psw;
}
public static List<GxkAccount> GetList()
{
List<GxkAccount> infoList=GxkAccount.findAll();
return infoList;
}
}
You are completely missing the mapping annotations for the properties of your class.
P.S. Please try to follow the Java naming conventions
Using mysql, we also faced this type of issue. We found in play framework application.conf:
jpa.dialect=org.hibernate.dialect.PostgreSQLDialect
we replaced this with
jpa.dialect=org.hibernate.dialect.MySqlDialect.
This solved the problem. If you are facing this issue you can try out this configuration setting.
We also faced the same issue. We were having create in the xml and #GeneratedValue on the id column. The resolution is remove the #GeneratedValue annotation and put the value of the id manually, also the jpa takes long by default so give long value e.g 1l.
To do the auto generation follow some another rule.
The issue around the JPA related auto generated Id is resolved as below:
Modify the Person.java model class to have the following annotations for the Id attribute:
#Id
#TableGenerator(name="TABLE_GEN",table="T_GENERATOR",pkColumnName="GEN_KEY",pkColumnValue="TEST",valueColumnName="GEN_VALUE",initialValue=1,allocationSize=1)
#GeneratedValue(strategy=GenerationType.TABLE, generator="TABLE_GEN")
public Long Id;
This will create a table in the mysql schema called T_GNERATOR which will have the tracking of the next value for Id and JPA over hibernate knows how to retrieve this value. The assumption is that the initial value for the Id is 1 and it is incremented by 1 on each new insertion into it as is obvious from the attributes of the annotation.
Related
I'm using Spring boot 2.7.0
And have the next entities in simple:
#Getter
#Setter
#Entity
public class Account {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Version
private Long version;
private String name;
}
#Getter
#Setter
#Entity
public class Event {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne
Account account;
private String message;
}
and jpa repositories:
#Repository
public interface AccountRepository extends JpaRepository<Account, Long> {
}
#Repository
public interface EventRepository extends JpaRepository<Event, Long> {
Page<Event> findAllByAccount(Account account, Pageable pageable);
}
In short I call
eventRepository.findAllByAccount(accountRepository.findById(1), PageRequest.of(1,10));
Problem is every call of last code increases the version field of Account by 1. So question is why? I don't call any update or save method.
And additionally the result of this behaviour is calling of method needs
#Transactional(readonly=false)
Otherwise if I write readonly=true that throws cannot execute UPDATE in a read-only transaction
ADDED:
full code of usage:
#Transactional
public Page<Event> events(Long accountId, int page) {
return eventRepository.findByAccount(findById(accountId), PageRequest.of(page, PAGE_SIZE));
}
#GetMapping("/events")
public List<EventResponse> listEvents(#RequestParam(value = "max", defaultValue = "0") int page) {
return eventService.events(1L, page).stream().map(EventResponse::of).toList();
}
It looks like hibernate is deriving lockMode type as either of WRITE or OPTIMISTIC_FORCE_INCREMENT or PESSIMISTIC_FORCE_INCREMENT based on isolation level of your database. As per reference hibernate decides this pessimistic locking by its own based on database you use.
As per doc, if lockmode type is either of what I mentioned above, Version will get automatically incremented even if you haven't changed anything i.e. even if you haven't do any update or save.
Please check database isolation level & based on that you might get an idea about this.
Edit: as you explicitly setting lockmode as write so my answer validates that because of WRITE mode, your version got incremented automatically.
The problem should be related in the code which is using the result of the find.
If you're modifying entities under a transaction they're going to be modified at the end of the method, when Spring in this case is going to close the transaction. In this part when transaction ends, the JPA provider (for example hibernate) aligns the relative entity record into the database with the 'java entity object' by an update.
I'm sorry. After trim all my code to the posted and debug I found my mistake:
In the begin I was retrieving Account in another method by .lock(Long) method instead of .findById(Long)
lock method is below:
#Lock(LockModeType.WRITE)
#Query("from Account where id = :id")
public Optional<Account> lock(Long id);
I'm currently playing around on Spring boot 1.4.2 in which I've pulled in Spring-boot-starter-web and Spring-boot-starter-jpa.
My main issue is that when I save a new entity it works fine (all cool).
However if I save a new product entity with the same id (eg a duplicate entry), it does not throw an exception. I was expecting ConstrintViolationException or something similar.
Given the following set up:
Application.java
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
ProductRepository.java
#Repository
public interface ProductRepository extends JpaRepository<Product, String> {}
JpaConfig.java
#Configuration
#EnableJpaRepositories(basePackages = "com.verric.jpa.repository" )
#EntityScan(basePackageClasses ="com.verric.jpa")
#EnableTransactionManagement
public class JpaConfig {
#Bean
JpaTransactionManager transactionManager() {
return new JpaTransactionManager();
}
}
Note JpaConfig.java and Application.java are in the same package.
ProductController.java
#RestController
#RequestMapping(path = "/product")
public class ProductController {
#Autowired
ProductRepository productRepository;
#PostMapping("createProduct")
public void handle(#RequestBody #Valid CreateProductRequest request) {
Product product = new Product(request.getId(), request.getName(), request.getPrice(), request.isTaxable());
try {
productRepository.save(product);
} catch (DataAccessException ex) {
System.out.println(ex.getCause().getMessage());
}
}
}
and finally Product.java
#Entity(name = "product")
#Getter
#Setter
#AllArgsConstructor
#EqualsAndHashCode(of = "id")
public class Product {
protected Product() { /* jpa constructor*/ }
#Id
private String id;
#Column
private String name;
#Column
private Long price;
#Column
private Boolean taxable;
}
The getter, setter and equalsHashcode.. are lombok annotations.
Miscellaneous:
Spring boot : 1.4.2
Hibernate ORM: 5.2.2.FINAL
This issue happens regardless if I annotate the controller with or without #Transactional
The underlying db shows the exception clearly
2016-11-15 18:03:49 AEDT [40794-1] verric#stuff ERROR: duplicate key value violates unique constraint "product_pkey"
2016-11-15 18:03:49 AEDT [40794-2] verric#stuff DETAIL: Key (id)=(test001) already exists
I know that is better (more common) to break the data access stuff into its own service layer instead of dumping it in the controller
The semantics of the controller aren't ReST
Things I've tried:
Spring CrudRepository exceptions
I've tried implementing the answer from this question, unfortunately my code never ever hits the DataAccesException exception
Does Spring JPA throw an error if save function is unsuccessful?
Again similar response to the question above.
http://www.baeldung.com/spring-dataIntegrityviolationexception
I tried adding the bean to my JPAconfig.java class that is:
#Bean
public PersistenceExceptionTranslationPostProcessor exceptionTranslation(){
return new PersistenceExceptionTranslationPostProcessor();
}
But nothing seemed to happen.
Sorry for long post, ty in advance
My solution is a lot cleaner. Spring Data already provides a nice way for us to define how an entity is considered to be new. This can easily be done by implementing Persistable on our entities, as documented in the reference.
In my case, as is the OP's, the IDs come from an external source and cannot be auto generated. So the default logic used by Spring Data to consider an entity as new if the ID is null wouldn't have worked.
#Entity
public class MyEntity implements Persistable<UUID> {
#Id
private UUID id;
#Transient
private boolean update;
#Override
public UUID getId() {
return this.id;
}
public void setId(UUID id) {
this.id = id;
}
public boolean isUpdate() {
return this.update;
}
public void setUpdate(boolean update) {
this.update = update;
}
#Override
public boolean isNew() {
return !this.update;
}
#PrePersist
#PostLoad
void markUpdated() {
this.update = true;
}
}
Here, I have provided a mechanism for the entity to express whether it considers itself new or not by means of another transient boolean property called update. As the default value of update will be false, all entities of this type are considered new and will result in a DataIntegrityViolationException being thrown when you attempt to call repository.save(entity) with the same ID.
If you do wish to perform a merge, you can always set the update property to true before attempting a save. Of course, if your use case never requires you to update entities, you can always return true from the isNew method and get rid of the update field.
The advantages of this approach over checking whether an entity with the same ID already exists in the database before saving are many:
Avoids an extra round trip to the database
We cannot guarantee that by the time one thread has determined that this entity doesn't exist and is about to persist, another thread doesn't attempt to do the same and result in inconsistent data.
Better performance as a result of 1 and having to avoid expensive locking mechanisms.
Atomic
Simple
EDIT: Don't forget to implement a method using JPA callbacks that sets the correct state of the update boolean field just before persisting and just after loading from the database. If you forget to do this, calling deleteAll on the JPA repository will have no effect as I painfully found out. This is because the Spring Data implementation of deleteAll now checks if the entity is new before performing the delete. If your isNew method returns true, the entity will never be considered for deletion.
I think you are aware of CrudRepository.save() is used for both insert and update. If an Id is non existing then it will considered an insert if Id is existing it will be considered update. You may get an Exception if your send the Id as null.
Since you don't have any other annotations apart from #Id on your id variable, The Unique Id generation must be handled by your code Or else you need to make use of #GeneratedValue annotation.
To build upon Shazins answer and to clarify. the CrudRepositroy.save() or JpaRespository.saveAndFlush() both delegate to the following method
SimpleJpaRepository.java
#Transactional
public <S extends T> S save(S entity) {
if (entityInformation.isNew(entity)) {
em.persist(entity);
return entity;
} else {
return em.merge(entity);
}
}
Hence if a user tries to create a new entity that so happens to have the same id as an existing entity Spring data will just update that entity.
To achieve what I originally wanted the only thing I could find was to drop back down to JPA solely, that is
#Transactional
#PostMapping("/createProduct")
public Product createProduct(#RequestBody #Valid Product product) {
try {
entityManager.persist(product);
entityManager.flush();
}catch (RuntimeException ex) {
System.err.println(ex.getCause().getMessage());
}
return product;
}
Here if we try to persist and new entity with an id already existing in the database it will throw will throw the constraint violation exception as we originally wanted.
Note that there are 3 scenarios here:
1. Setting ID manually
If there is no choice(like the OP), i.e if you are setting your own id "manually", Spring Data JPA is assuming that you want to check if there are duplicates(hence the SELECT), so it will do a "(i)SELECT + (ii)INSERT" if there is no existing record or a "(i)SELECT + (ii)UPDATE" if there is already an existing record.
In short, 2 SQLs!
2. Use an ID Generator
Cleaner & better, for example:
#Id
#GeneratedValue(generator = "my-uuid")
#GenericGenerator(name = "my-uuid", strategy = "uuid2")
private UUID id;
Result: there is ALWAYS only 1 INSERT statement.
3. Implement Persistable and isNew()
This has already been brilliantly answered by #adarshr, but is also more painful, i.e to implement Persistable(instead of Serializable), and implement the isNew() method.
Result: Also, 1 INSERT statement.
According to Spring Data documentation Spring persists an entity if does not exists or merge, this means update, the existing one:
Saving an entity can be performed via the CrudRepository.save(…)-Method. It will persist or merge the given entity using the underlying JPA EntityManager. If the entity has not been persisted yet Spring Data JPA will save the entity via a call to the entityManager.persist(…)-Method, otherwise the entityManager.merge(…)-Method will be called.
I'm totally new to Spring MVC but still trying to understand its methods and its way of referencing things. There's a video tutorial course I'm following.
I'm trying to implement a Model through a class.
ProductDaoImpl.java
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import java.util.List;
#Repository
public class ProductDaoImpl implements ProductDao {
#Autowired
private SessionFactory sessionFactory;
#Override
public void addProduct(Product product) {
Session session = sessionFactory.getCurrentSession();
session.saveOrUpdate(product);
session.flush();
}
#Override
public Product getProductById(String id) {
Session session = sessionFactory.getCurrentSession();
Product product = (Product) session.get(Product.class.productId);
// unable to resolve the productId on get()
return product;
}
#Override
public List<Product> getAllProducts() {
return null;
}
#Override
public void deleteProduct(String id) {
}
}
ProductDao.java
import java.util.List;
public interface ProductDao {
void addProduct(Product product);
Product getProductById(String id);
List<Product> getAllProducts();
void deleteProduct(String id);
}
Product.java Model
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
#Entity
public class Product {
#Id
#GeneratedValue(strategy = GenerationType.AUTO) //tells the system that when an instance is put to database, it will be numbered automatically starting from 1
private String productName;
private String productCategory;
private String productDescription;
private double productPrice;
private String productDimension;
private String productStatus;
private int unitInStock;
private String productManufacturer;
private String productId;
}
However, it's unable to resolve the productId argument in
#Override
public Product getProductById(String id) {
Session session = sessionFactory.getCurrentSession();
Product product = (Product) session.get(Product.class.productId);
return product;
}
Is get() method able to access the fields of Product.class?
Is it asking for a field in Product.class.fieldHere?
I don't understand why it can't resolve the productId
I hope you can help.
Thanks.
The expression Product.class.productId doesn't make sense in Java. Product.class is a class literal, meaning that it's a constant value that represents the Product class, an instance of java.lang.Class. Class has no productId field.
Additionally, you should read the Javadoc for the method--it takes two parameters, a Class object (to tell it what sort of thing you're getting) and an ID. Your call should therefore be session.get(Product.class, id), and if you're using Hibernate 5, you don't need to cast to a Product.
All of this is rather moot, however--instead of hand-rolling a DAO targeting Hibernate, use JPA (which provides advantages such as a generic API, eliminating the need for casting) and Spring Data (which will autogenerate this entire DAO for you from nothing but an empty interface declaration). Additionally, you're dealing with topics that can get complicated, and you would do well to go through some exercises to learn core Java before tackling something like ORM.
session.get(Product.class.productId);
That's not valid Java code. get() expects two arguments: the entity class, and the ID of the entity to get. Arguments in Java are separated by a comma.
session.get(Product.class, productId);
But your variable isn't even named productId. It's named id. So the code should be
session.get(Product.class, id);
This is beginner Java stuff. I strongly suggest you practice with simpler Java exercises before using Spring and Hibernate, which are complex stuff.
session.get accepts two parameters, one is the class of your entity and the other one is the identifier
Product product = (Product) session.get(Product.class,id);
So I have looked at various tutorials about JPA with Spring Data and this has been done different on many occasions and I am no quite sure what the correct approach is.
Assume there is the follwing entity:
package stackoverflowTest.dao;
import javax.persistence.*;
#Entity
#Table(name = "customers")
public class Customer {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private long id;
#Column(name = "name")
private String name;
public Customer(String name) {
this.name = name;
}
public Customer() {
}
public long getId() {
return id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
We also have a DTO which is retrieved in the service layer and then handed to the controller/client side.
package stackoverflowTest.dto;
public class CustomerDto {
private long id;
private String name;
public CustomerDto(long id, String name) {
this.id = id;
this.name = name;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
So now assume the Customer wants to change his name in the webui - then there will be some controller action, where there will be the updated DTO with the old ID and the new name.
Now I have to save this updated DTO to the database.
Unluckily currently there is no way to update an existing customer (except than deleting the entry in the DB and creating a new Cusomter with a new auto-generated id)
However as this is not feasible (especially considering such an entity could have hundreds of relations potentially) - so there come 2 straight forward solutions to my mind:
make a setter for the id in the Customer class - and thus allow setting of the id and then save the Customer object via the corresponding repository.
or
add the id field to the constructor and whenever you want to update a customer you always create a new object with the old id, but the new values for the other fields (in this case only the name)
So my question is wether there is a general rule how to do this?
Any maybe what the drawbacks of the 2 methods I explained are?
Even better then #Tanjim Rahman answer you can using Spring Data JPA use the method T getOne(ID id)
Customer customerToUpdate = customerRepository.getOne(id);
customerToUpdate.setName(customerDto.getName);
customerRepository.save(customerToUpdate);
Is's better because getOne(ID id) gets you only a reference (proxy) object and does not fetch it from the DB. On this reference you can set what you want and on save() it will do just an SQL UPDATE statement like you expect it. In comparsion when you call find() like in #Tanjim Rahmans answer spring data JPA will do an SQL SELECT to physically fetch the entity from the DB, which you dont need, when you are just updating.
In Spring Data you simply define an update query if you have the ID
#Repository
public interface CustomerRepository extends JpaRepository<Customer , Long> {
#Query("update Customer c set c.name = :name WHERE c.id = :customerId")
void setCustomerName(#Param("customerId") Long id, #Param("name") String name);
}
Some solutions claim to use Spring data and do JPA oldschool (even in a manner with lost updates) instead.
Simple JPA update..
Customer customer = em.find(id, Customer.class); //Consider em as JPA EntityManager
customer.setName(customerDto.getName);
em.merge(customer);
This is more an object initialzation question more than a jpa question, both methods work and you can have both of them at the same time , usually if the data member value is ready before the instantiation you use the constructor parameters, if this value could be updated after the instantiation you should have a setter.
If you need to work with DTOs rather than entities directly then you should retrieve the existing Customer instance and map the updated fields from the DTO to that.
Customer entity = //load from DB
//map fields from DTO to entity
So now assume the Customer wants to change his name in the webui -
then there will be some controller action, where there will be the
updated DTO with the old ID and the new name.
Normally, you have the following workflow:
User requests his data from server and obtains them in UI;
User corrects his data and sends it back to server with already present ID;
On server you obtain DTO with updated data by user, find it in DB by ID (otherwise throw exception) and transform DTO -> Entity with all given data, foreign keys, etc...
Then you just merge it, or if using Spring Data invoke save(), which in turn will merge it (see this thread);
P.S. This operation will inevitably issue 2 queries: select and update. Again, 2 queries, even if you wanna update a single field. However, if you utilize Hibernate's proprietary #DynamicUpdate annotation on top of entity class, it will help you not to include into update statement all the fields, but only those that actually changed.
P.S. If you do not wanna pay for first select statement and prefer to use Spring Data's #Modifying query, be prepared to lose L2C cache region related to modifiable entity; even worse situation with native update queries (see this thread) and also of course be prepared to write those queries manually, test them and support them in the future.
I have encountered this issue!
Luckily, I determine 2 ways and understand some things but the rest is not clear.
Hope someone discuss or support if you know.
Use RepositoryExtendJPA.save(entity). Example:
List<Person> person = this.PersonRepository.findById(0)
person.setName("Neo");
This.PersonReository.save(person);
this block code updated new name for record which has id = 0;
Use #Transactional from javax or spring framework. Let put #Transactional upon your class or specified function, both are ok. I read at somewhere that this annotation do a "commit" action at the end your function flow. So, every things you modified at entity would be updated to database.
There is a method in JpaRepository
getOne
It is deprecated at the moment in favor of
getById
So correct approach would be
Customer customerToUpdate = customerRepository.getById(id);
customerToUpdate.setName(customerDto.getName);
customerRepository.save(customerToUpdate);
We use annotations for mapping the entity class with the database table by simply specifying #Entity and more like #Id, table joins and many things. I do not know how these entity variables are getting mapped with database table. Can anyone give a short description for understanding.
Thanks :)
Well the idea is to translate your objects and their connections with other objects into a relational database. These two ways of representing data (objects defined by classes and in tables in a database) are not directly compatible and that is where a so called Object Relational Mapper framework comes into play.
So a class like
class MyObject
{
private String name;
private int age;
private String password;
// Getters and setters
}
Will translate into a database table containing a column name which is of type varchar, age of type int and password of type varchar.
Annotations in Java simply add additional information (so called meta data) to your class definitions, which can be read by any other class (e.g. JavaDoc) and in the case of the Java Persistence API will be used by an ORM framework like Hibernate to read additional information you need to translate your object into the database (your database table needs a primary id and some information - like what type of a relation an object has to another - can't be automatically determined by just looking at your class definition).
Annotations are very well explained here:
http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/
annotations are just metadata on a class, nothing magical. You can write your own annotations. Those annotations are given retention policies of runtime (which means you have access to that metadata at runtime). When you call persist etc the persistence provider iterates through the fields (java.lang.reflect.Field) in your class and checks what annotations are present to build up your SQL statement. Try writing your own annotation and doing something with it. It won't seem very magical after that.
in your case annotation working means mapping with tablename with entity class is look like as ....
#Entity
#Table(name = "CompanyUser")
public class CompanyUserCAB implements java.io.Serializable
{
private long companyUserID;
private int companyID;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "companyUserID")
public long getCompanyUserID()
{
return this.companyUserID;
}
public void setCompanyUserID(long companyUserID)
{
this.companyUserID = companyUserID;
}
#Column(name = "companyID")
public int getCompanyID()
{
return this.companyID;
}
public void setCompanyID(int companyID)
{
this.companyID = companyID;
}
}