Is there a way to return Iterable< IUser > where IUser is a projection of User entity.
Example<User> userExample = Example.of(user, userMatcher);
Iterable<User> foundUsers = userRepository.findAll(userExample, Sort.by("createdAt").descending());
Instead of sticking with spring data auto generated query and response type.
You can create your own HQL query by using #Query annotation so that you can except your custom return type.
Example :
#Query(" select user from User as user where user.userName like %:username% order by createdAt desc")
public List<User> findAllByUserName(String username);
Related
public interface UserDao {
User getUserById(Long id);
void saveUser(User user);
List<UserDto> getAllUsers();
boolean isExistUserByEmail(String email);
boolean isExistUserByUserName(String userName);
// get users by id list
List<User> getUsersByIdIn(List<Long> idList);
// get all active users
List<UserDto> getAllActiveUsers();
User getUserByEmail(String email);
void saveAllUsers(List<User> userList);
List<Object[]> getAllInstructors();
}
This my dao impl method
#Override
public List<Object[]> getAllInstructors() {
return userRepository.getAllInstructors();
}
This is the query from my repository layer
#Query(value = "select distinct u.first_name, u.last_name, u.full_name, u.id from public.user u inner join public.users_group ug on u.id = ug.user_id and ug.group_list_id=1 WHERE status=1 ORDER BY u.id DESC", nativeQuery = true)
This is the method in my controller layer
#GetMapping("/instructors")
public List<Object[]> getAllIntsructors() {
return userService.getAllInstructors();
}
Result when I call the api on postman
The result I expect is:
first_name: "Iresha"
second_name: "Vishwakala"
But I don't get the key. I only get an array of objects showing me the values.
The way you are using your Repo is not a good practice. To be honest I have never seen it before.
This would be the correct way to do it:
public interface UserRepository extends JpaRepository<UserEntity, Long> // Here the first is the Entity which will be fetched by this repo, and the second is the type of ID that this Entity has.
{
// I am supposing that your entity is UserEntity and has an ID of type Long.
// Here come the queries which must return primitives or UserEntity (list, set etc.)
// An example query would be:
#Query(value = "....", nativeQuery = true) List<UserEntity> getUsersAsYouWant();
}
The JpaRepository makes use of Java Generics (hence the <>), that is why you must supply the class the types that it has to map the DB rows/data to. If you want to return specific types/Dtos/List you may use the same Repo but with different Query building (not native but JPQL). But that would be yet another question. If you want to check more, see my answer here.
Is it possible to map the results of a Hibernate #Query like this (in a #Repository interface extending #JpaRepository):
#Query("select u.id, u.email, u.status from user u")
public SimpleUserDTO getAllUsersSimpleData();
directly to a Java object like this:
public class SimpleUserDTO {
private Long id;
private String email;
private String status;
}
What I know, is that doing something like this:
Query query = session.createQuery("select u.id, u.email, u.status from user u");
the result can be extracted to a List<Object[]>:
List<Object[]> users = (List<Object[]>) query.list();
But is it possible to map it directly to a List<SimpleUserDTO> without writing additional method that will map the values to SimpleUserDTO?
You have two options.
Option 1: Constructor Expression:
#Query("select new <insert_package_here>.SimpleUserDTO(u.id, u.email, u.status) from user u")
public List<SimpleUserDTO> getAllUsersSimpleData();
Option 2: Use Interface projection
Turn your DTO into an interface and you can use it without #Query annotation
public List<SimpleUserDTO> getAllUsersSimpleData();
Please find out more about projections and Spring Data JPA in the documentation:
https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#projections
I am using Spring JPA to perform all database operations. However I don't know how to select specific rows (connected by simple WHERE clause) from a table in Spring JPA?
For example:
SELECT * FROM user where name=agrawalo AND email=abc#example.com
User Class:
#Entity
Class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long userId;
#Column(nullable = false)
private String name;
#Column(nullable = false)
private String email;
// Getters and Setters
}
Repository:
public interface UserRepository extends JpaRepository<User, Integer> {
}
You don't need to write queries for such simple things if you are using spring-data-jpa. you can write a method name and spring-data will formulate a query based on your method name and get the results.
public interface UserRepository extends JpaRepository<User, Integer> {
Optional<User> findByNameAndEmail(String name, String email)
}
Create a method like above and call the method with the required arguments.
If you don't want(not advisable) to use Optional, you can just use User as return type. In such case, if there are no entries matching your arguments then you would have null returned.
public interface UserRepository extends JpaRepository<User, Integer> {
public User findUserByNameAndEmail(String name,String email);
}
Implementation will be created on the fly.
I know I am very very late to this but I still want to provide another solution that one would like to use. This is particularly useful when you think the queries generated by method names do not serve the purpose that you want and you really want to write the native queries. To do that, you can actually use the #Query annotation in your repository and put your query inside it like below:
#Query(value = "SELECT * FROM user where name = ?1 AND email = ?2", nativeQuery = true)
List<User> getUserByNameAndEmail(String name, String email);
Here the #Query tells that the query provided in the value attribute needs to be executed and the nativeQuery attribute tells that it is a native sql query.
Notice that values for name and email are provided as ?1 and ?2 respectively which means these are placeholders and will be replaced by the parameters that getUserByNameAndEmail repository method will receive at runtime in variables name and email.
Simply you can declare below method in you repository interface, implementation will be taken care by Spring-data-jpa
User findByNameAndEmail(String name, String email);
My UserRepository:
public interface UserRepository extends CrudRepository<User, Integer> {
List<User> findAll(List<Integer> ids);
}
Error:
Caused by:
org.springframework.data.mapping.PropertyReferenceException: No
property findAll found for type User
Refer - http://docs.spring.io/spring-data/commons/docs/current/api/org/springframework/data/repository/CrudRepository.html?is-external=true#findAll-java.lang.Iterable-
Can some one tell me how to get list of User objects based on List of Id's.
This is working
#Query(" select new User(id,x,y,z) from User b where b.id in ?1 ")
List<User> findById(List<Integer> id);
Firstly, I would rename the repository to UserRepository, because having 2 User classes is confusing.
findAll(), by definition, is meant to get all the models with no criteria. You should add a method named
findByIdIn(Collection<Integer> ids)
Use List<User> findAll(Iterable<Integer> ids) or List<User> findByIdIn(List<Integer> ids)
I have an User entity with Set cars (oneToMany). Also I have a method:
#Transactional(readOnly = true)
public Optional<User> getUserWithCars(Long id) {
return userRepository.findOneById(id).map(u -> {
u.getCars().size();
return u;
});
}
Lazy fetching works fine. But what if I have to fetch set of users with cars? I tried to use users.forEach(u -> u.getCars().size()); but received a popular no Session exception.
P.S. I need lazy fetch, not eager.
In repository:
#Query("SELECT u FROM User u LEFT JOIN FETCH u.cars")
public Set<User> getUserWithCars()
in spring data jpa you can write query method
Optional<User> findFirstWithCarsById(Long id);
for more information look to documentation