I've just started learning Spring Boot and am using a H2 database, I've got mostly everything working but I'm running into trouble trying to make a slightly more complex request. I've got 2 tables 'User' and 'Purchase', and I want to create and end point that returns all purchases that contain a given users ID. This seems simple if I used an SQL join or some similar query but I have no idea how to implement one.
I have a repository (CrudRepository) for both user and purchases, and then a service for each that gets the relevant data from database. This works perfect for the basic needs such as get, getById, etc. But I have no idea how to specify queries such as join and what not.
public interface UserRepo extends CrudRepository<User, Integer> {}
public interface ReceiptRepo extends CrudRepository<Receipt, Integer> {}
#Service
public class UserService {
#Autowired
UserRepo userRepo;
public User getUser(int id) { return userRepo.findById(id).get(); }
}
#RestController
public class UserController {
#Autowired
UserService userService;
#GetMapping("/user/{id}")
private User getUser(#PathVariable("id") int id) {
return userService.getUser(id);
}
}
That's basically the set up for both entities, and I'm not sure where and how I'd write more specific queries. Any help would be greatly appreciated.
Yoy can use #Query() annotation in order to write query.
You need to declare a method in your repo and on that method you can put this annotation.
Eg:
#Query("SELECT u FROM User u WHERE u.status = 1")
Collection<User> findAllActiveUsers();
You can take some more idea about this from here
Related
Guess easier if I show you my example:
#Entity
class User {
Long id;
Status status;
}
enum Status {
NEW("N"), DELETED("D")
}
I have an AttributeConverter on Status so in DB the enum is stored with one character.
In my database I have entities like:
Table user
------------
Id Status
1 N
2 N
3 D
4 N
5 D
I want a method that list the Users with Status D. Something like this:
#Repository
public interface UserRepository extends JpaRepository<User, Long> {
List<User> findByStatusEqualsD();
or
List<User> findByStatusEqualsDeleted();
problem is these are not working
}
I could write this:
List<User> findByStatus(Status status);
And call it as repo.findByStatus(Status.DELETED) but I want a method what returns only the deleted users.
If I call it as repo.findByStatus(Status.NEW) then it will return the new users.
I prefer to not write a #Query, I hope it is possible what I'm asking without doing it...
Thanks in advance.
Such behavior is not supported.
Method name is translated into JPQL expression (which is the same as used in #Query) with parameters in it (if needed) so you have to provide these. (https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#jpa.query-methods.query-creation)
If you want query parameters to be hardcoded - #Query is what you need.
Alternatively you can have default method in your repository calling the parametrized one as mentioned here JpaRepository with Enum: findAllByOfferState_ACTIVE. NoSuchElementException
Easy,
You don't need a repo for that. Create a Service instead:
public interface UserDAOService{
List<User> getAllDeletedUsers();
}
And then just implement it with hardcoded findByStatus method from repo:
#Service
public class UserDAOServiceImpl implements UserDAOService{
private final UserRepository userRepository;
public UserDAOServiceImpl(UserRepository userRepository) {
this.userRepository= userRepository;
}
#Override
public List<Author> getAllDeletedUsers();
return userRepository.findByStatus(Status.DELETED);
}
In my legacy application, I have a country table, state table and a mapping table for country and state with few additional columns.
I have created an entity class like this.
class CountryStateMapping {
#Id
private long id;
private Long countryId;
#OneToOne
#JoinColumn(name="state_id")
private State state;
//getters seters
}
My repository.
public interface CountryStateMapping extends JpaRepository<CountryStateMapping, Long>{
Optional<CountryStateMapping> findByStateId(long stateId);
Optional<CountryStateMapping> findByState(State state);
}
I would like to check if the state exists in the mapping table. Both of the below approaches do not work.
countryStateMapping.findByStateId(long stateId)
countryStateMapping.findByState(State state)
What is the right way?
Its not the correct way i feel.The correct way for doing this will be
public interface CountryStateMappingRepository extends JpaRepository<CountryStateMapping, Long> {
Optional<CountryStateMapping> findByStateId(long stateId);
#Query("select s.something from State s" )
Optional<CountryStateMapping> findByState(State state);
}
This implies two things
By extending JpaRepository we get a bunch of generic CRUD methods to create, update, delete, and find
2.It allows Spring to scan the classpath for this interface and create a Spring bean for it.
Also you need some configuration.For that you need to create a configuration class to be used with your data source.You can find many examples to do the same and one such is https://www.baeldung.com/the-persistence-layer-with-spring-data-jpa.
You can also use custom queries and simple queries using the #Query annotation.
Thanks
Try with an underscore for id like below;
public interface CountryStateMapping<CountryStateMapping, Long>{
Optional<CountryStateMapping> findByState_Id(long stateId);
Optional<CountryStateMapping> findByState(State state);
}
I am able to get the property value in Spring classes like below:
#Value("${database.name}")
private String databaseName;
I have to execute a native query by joining different tables which are in different databases.
#Query(value="select t1.* FROM db1.table1 t1 INNER JOIN db2.table2 t2 ON t2.t1_id1 = t1.id1")
Instead of hard coding database names i.e., db1 and db2 here, I have to get them from properties file.
how to get the property value inside the #Query annotation in Spring Data JPA Repository ?
I don't know if it is possible, but if not, you can consider this approach:
Instead of using properties in Repository's #Query directly, you can use params in the query but when you call the actual method - you can provide values from .properties.
Imagine you have simple repository:
public interface UserRepository extends JpaRepository<User, Long> {
// query with param
#Query("select u from User u where u.lastname = :lastname")
User findByLastname(#Param("lastname") String lastname);
}
Then, let's say you have some Service or Controller where you need to use your Repository - you can inject properties there and pass them to your method:
#Service
public class UserService {
// this comes from .properties
#Value("${user.lastName}")
private String userLastName;
#Autowired
private UserRepository userRepository;
public User getUser() {
// you pass it as param to the repo method which
// injects it into query
return userRepository.findByLastname(userLastName);
}
}
This is just an example. But I believe it may be useful.
Happy hacking :)
I have been working to generalize the methods of the DAO for a project using Spring, JPA and Hibernate. However, I am still very much learning Spring, Java, and coding in general.
Is the below design bad or perfectly fine? Is there a better way to accomplish the same thing? Any advice would be greatly appreciated.
I have simplified the class:
#Repository
public class TestRepository
{
#PersistenceContext
private EntityManager entityManager;
public List<?> getListResults(Class<?> dtoClass, String sqlString)
{
List<?> returnList = null;
Query query = entityManager.createNativeQuery(sqlString, dtoClass);
try
{
returnList = (List<?>) query.getResultList();
}
catch (Exception e)
{
}
return returnList;
}
}
Spring Data JPA is the must convenient way in order to interact with your databases because it helps you to avoid the common mistakes that occurs when you try to configure your ORM mapping, entityManager, transacctionManager and all the rest of necessary components in order to establish a communication between your entity domains and your database.
For example you have a pojo like this:
#Entity
public class Item {
#Id
private Long id;
......
}
You can create an interface in order to get or put information to the item repository like this:
public interface ItemRepository extends from JpaRepository<Item,Long>{}
When you need to save the Item just #Autowired the ItemRepository, this is the must important part because the previous interface that is created without methods now exposes ready-to-work methods that will interact with your database, this is the abstraction level that makes Spring Data JPA very useful:
#Autowired
ItemRepository itemRepo
public void createItem(){
Item item = new Item();
itemRepo.save(item);
//or you can get information
List<Item> itemList = itemRepo.findAll();
}
More information in Spring Data JPA Documentation
How about using Spring Data Repositories?
#Repository
public interface SomethingRepository extends JpaRepository<Something, Long> {
}
That way you get lots of methods without having to manually write your SQL query as a string, you retain type safety and you can leverage the power of JPA queries and dynamic proxies that do this whole SQL business for you.
Is there a way to override the findAll query executed by Spring Data Rest?
I need a way of filtering the results based on some specific criteria and it seems that using a #NamedQuery should be along the lines of what I'm looking for so I setup a test.
#Entity
#Table(name = "users")
#NamedQueries({
#NamedQuery(name = "User.findAll", query="SELECT u FROM User u WHERE u.username = 'test'"),
#NamedQuery(name = "User.findNameEqualsTest", query="SELECT u FROM User u WHERE u.username = 'test'")
})
public class User implements Serializable, Identifiable<Long> { }
With this in place I would expect SDR to utilize my findAll() query (returning 1 result) but instead it executes the same old findAll logic (returning all results).
In my Repository I added:
#Repository
#RestResource(path = "users", rel = "users")
public interface UserJpaRepository extends JpaRepository<User, Long> {
public Page<User> findNameEqualsTest(Pageable pageable);
}
and in this case it DOES pick up the provided #NamedQuery. So...
How should I go about overriding the default findAll() logic? I need to actually construct a complex set of criteria and apply it to the result set.
In the upcoming version 1.5 (an RC is available in our milestone repositories) of Spring Data JPA you can simply redeclare the method in your repository interface and annotate it with #Query so that the execution as query method is triggered. This will then cause the named query to be looked up just as you're already used to from query methods:
interface UserJpaRepository extends PagingAndSortingRepository<User, Long> {
#Query
List<User> findAll();
Page<User> findNameEqualsTest(Pageable pageable);
}
A few notes on your repository declaration:
You don't need to annotate the interface with #Repository. That annotation doesn't have any effect at all here.
Your #RestResource annotation configures the exporter in a way that will be the default anyway in Spring Data REST 2.0 (also in RC already). Ging forward, prefer #RestRepositoryResource, but as I said: the pluralization will be the default anyway.
We generally don't recommend to extend the store specific interfaces but rather use CrudRepository or PagingAndSortingRepository.
Yes, you can create your Implementation of your Repository interface, there is acouple section in
http://docs.spring.io/spring-data/jpa/docs/1.4.3.RELEASE/reference/html/repositories.html#repositories.custom-implementations
Repository
#Repository
public interface PagLogRepository extends JpaRepository<PagLogEntity, Long>, PagLogCustomRepository {
Custom Interface
public interface PagLogCustomRepository {
PagLogEntity save(SalesForceForm salesForceForm) throws ResourceNotFoundException;
Custom implementation
public class PagLogRepositoryImpl implements PagLogCustomRepository {
#Override
public PagLogEntity save(final SalesForceForm salesForceForm) throws ResourceNotFoundException {
query = emEntityManager.createNamedQuery("findItemFileByDenormalizedSku", ItemFileEntity.class);
query.setParameter("skuValue", rawSku);
Instead of override save make it with findAll, then you can create complex customization