Say, I have the following entity class:
Person.java
#Entity
public class Person {
#Id
private String name;
private String[] cars;
// Constructor, getters and setters
}
And the repository:
PersonRepository.java
public interface PersonRepository extends CrudRepository<Person, String> {
// this is unclear!
List<Person> getAllByCars...(String car)
}
Is there a method that returns all persons, whose car array contains one given car (the String parameter above)?
For me, it seems that all supported JPA keywords can only deal with single elements, but not with arrays.
Thanks for help!
Ideally, You should declare cars as a separate Entity like this
#Entity
public class Person {
#Id
private String name;
private List<Car> cars;
// Constructor, getters and setters
}
If not you should change Array to List at the least.
change
private String[] cars;
to
#ElementCollection
private List<String> cars;
Then You have to write a Query like this
#Query("select p from Person p WHERE :car in elements(p.cars)")
List<Person> getAllByCars...(#Param("car") String car)
I'm guessing at how you are currently storing the cars information and suggesting a possible solution:
#Entity
public class Car {
#Id
private String name;
#Column
private String person_name;
}
public interface CarRepository extends JpaRepository<Car, String> {
//Result will have all cars with the person_name identifying the Person #Entity
List<Car> findByName(String name);
}
Related
I want to disable #Entity Annotation for particular class.
Here is my sample code.
#Component
public class GenericDropDown{
private Integer id;
private String key;
private String value;
// Standard getter and setter
The above class is used for fetching data from multiple table for rendering different dropdown list from different tables.
How I can achieve this without #Entity Annotation
Here is my sample code.
#Component
public class GenericDropDown{
private Integer id;
private String key;
private String value;
// Standard getter and setter
#Repository
public class DropDownDao {
#Autowired
private EntityManager entityManager;
public Object runNativeQuery() {
#SuppressWarnings("unchecked")
List<Priority> o= entityManager.createNativeQuery("select Id,PRKEY,PRVALUE from Priority",Priority.class)
.getResultList();
return o;
}
}
**Error:**Unknown entity: com.min.test.Project.entity.Priority; nested exception is org.hibernate.MappingException: Unknown entity: com.min.test.Project.entity.Priority
You can select List of Objects array and map them yourself.
List<Object[]> o = entityManager.createNativeQuery("select Id,PRKEY,PRVALUE from Priority").getResltList();
List<MyClass> result = o.stream().map(arr -> new MyClass((Long) arr[0], (String) arr[1])).collect(Collectors.toList());
Or you also can use a JdbcTemplate instead of EntityManager:
#Autowired
private JdbcTemplate jdbcTemplate;
public List<MyClass> runQuery() {
String select = "select Id,yourParameterHere from Priority";
return jdbcTemplate.query(select, (rs, rowNum) -> new MyClass(rs.getLong("Id"), rs.getString("yourParameterHere")));
}
Need your help here in a Spring Data CrudRepository on how to do a findby of nested fields.
My class is of following structure and I need to query using truckId which is of the nested objects
#Document(collection = "unt-truck")
public class TruckModelDTO {
private String type;
private TestDTO testDTO;
}
Class TestDTO.java
public class TestDTO{
private TruckDTO truckDTO;
Private String version;
}
Class TruckDTO.java
public class TruckDTO {
private String truckId;
private String legacySystem;
}
Class TruckRepository.java
#Repository
public interface TruckRepository extends MongoRepository<TruckModelDTO, String> {
// TruckModelDTO findByTruckId(String truckid);
}
So how should I use findby for truckId which is inside a nested class?
You can use with either Entity or DTO as response. but you have to mention the relation between two or three Entity based on you requirement.
I have created Entity. you have to create DTO with same based on entity then apply main DTO as return type in JPA Repository query.
1.Entity
#Entity
public class TruckModel {
private String type;
// mention the relation based on your requirement
private Test test;
}
Entity
#Entity
public class Test {
// here mention the relation based on you requirement
private Truck truck;
Private String version;
}
3.Entity
#Entity
public class Truck {
private String truckId;
private String legacySystem;
}
Repository
#Repository
public interface TruckModelRepository extends MongoRepository<TruckModel, String> {
TruckModelDTO findByTestTruckTruckId(String truckid);
}
This is my Book class:
#Entity
#Table(name="book")
public class Book {
#JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
#ManyToOne(targetEntity=Category.class,cascade=CascadeType.ALL,fetch=FetchType.LAZY)
#JoinColumn(name="CategoryId")
public Category category;
#Id
#GeneratedValue(strategy=GenerationType.AUTO)
#Column(length=10)
private int book_id;
#Column(length=128)
private String title;
#Column(length=64)
private String author;
#Column(length=200)
private String description;
#Column(length=10)
private int ISBN;
#Column(length=10)
private float price;
private Date published_Date;
#Lob
#Column
#Basic(fetch = FetchType.LAZY)
private byte[] icon;
//getter and setter
}
This is my Category class:
#Entity
#Table(name="category1")
public class Category {
#Id
#Column(length=12)
#GeneratedValue(strategy=GenerationType.AUTO)
public int CategoryId;
#Column(length=50)
public String CategoryName;
//#JsonBackReference
#OneToMany(mappedBy="category")
private List<Book> books = new ArrayList<Book>();
//getter and setter
}
The relationship between them is one to many.
This is my Category Service class
#Service
#Transactional
public class AdminServiceImpl implements AdminService {
#Autowired
private CategoryDao dao;
#Autowired
private BookDao dao1;
#Override
public List<Category> getAllCategory(){
return dao.findAll();
}
}
My Controller class
#RestController
#RequestMapping("/bookstore")
public class CategoryController {
#Autowired
private AdminService service;
#GetMapping("/GetAllCategory")
private ResponseEntity<List<Category>> getAllCategory() {
List<Category> catlist = service.getAllCategory();
return new ResponseEntity<List<Category>>(catlist, new HttpHeaders(), HttpStatus.OK);
}
}
My category table already has data.When i try to display them it is showing double values.
Displaying values using Postman
The Category table in the Database: Database table
Jackson's ObjectMapper uses the Java bean pattern and it expects the following
public class Foo {
public Object bar;
public Object getBar() {...}
public void setBar(Object bar) {...}
}
The getters and setters start with get and set, respectively, followed by the corresponding field name with its first letter capitalized.
Change
CategoryId to categoryId (first letter lowercase)
and
CategoryName to categoryName
I am currently learning spring boot , hibernate and Spring Boot JPA
I developing a Classroom App for coaching centers and institutes .
In it, students enrolled to multiple courses in a single institute
The Student Entity class :
#Entity
#Table(name = "student")
public class Student {
private String name;
private String dob;
private String gender;
private String address;
private String email;
private Integer mobile;
private String joined;
private Integer instID;
#Id
private String studentid;
getters and setters()....
}
Course Table Entity class
#Entity
#Table(name = "courses")
public class Course {
private String name;
private String description;
private String logo;
private String start;
private String end;
private Integer fee;
#Id
private String courseid;
private Integer instID;
getters and setters();
}
Enrolled Classes Table's Entity class
public class EnrolledCourses {
#Id
String enrollID;
String courseid;
String studentid;
Date joined;
getters and setters()...
}
JPA Repository
#Repository
public interface StudentRepository extends CrudRepository<Student, String> {
Student findTopByInstIDOrderByStudentidDesc(int instID);
}
#Repository
public interface CourseRepository extends CrudRepository<Course,String> {
}
#Repository
public interface EnrolledRepository extends CrudRepository<Course,String> {
}
My Need
Now I am retrieving enrolled students for a given course in a given institute... by using this MySQL query
SELECT
`enrolled_courses.enrollID`,
`student.name`, `student.studentid`
FROM `enrolled_courses`
INNER JOIN `student`
WHERE
`enrolled_courses.studentid` = `student.studentid`
AND
`student.instID` = 13
AND
`enrolled_courses.courseid` = '13I01C' ;
Now I need to implement this Inner join query in CourseRepository (or enrolledstudent repo)
How to achieve this ?
Please guide me
If we use hibernate mapping in EnrolledCourses entity like
#Entity
public class EnrolledCourses {
#Id
String enrolledId;
#ManyToOne
Student student;
#ManyToOne
Course course;
Date joined;
getters and setters()...
}
from the above mappings without using any SQL queries, you can retrieve all student who comes under a particular course
By using the method in the interface
#Repository
public interface EnrolledRepository extends CrudRepository<EnrolledCourses,String> {
List<EnrolledCourses> findByCourse_CourseId(String courseId);
}
if we have some relations between the entities we can easily retrieve all the fields using Jpa.
I have been learning myself MongoDB implementation in Spring Boot.
However, I came into a problem with complex queries.
I cannot find any right solution for how to implement complex queries to MongoDB from Spring boot.
I am querying the database with MongoRepository interface implementation.
Let's say that I have three collections:
Person - 1 Person can have many Pets.
Pet - 1 Pet can have 1 PetToy and 1 Person who owns him.
PetToy - 1 PetToy can belong to 1 Pet.
POJO classes are bellow
What do I want to achieve?
I want to make a query, which would be returned me a Person, whose Pet has a Toy (PetToy) with the name "Teddy".
I could not have found a way how to do it. Furthermore, is it the best practice to even use such complex queries, or is it better to write more of little ones in MongoDB?
POJOs:
#Document
#Data
#ToString
public class Person {
#Id
private String id;
private String firstname;
private String lastname;
private int age;
#DBRef
private Pet pet;
}
#Document
#Data
#ToString
public class Pet {
#Id
private String id;
private String name;
private int age;
#DBRef
private List<PetToy> toys;
}
#Document
#Data
#ToString
public class PetToy {
#Id
private String id;
private String name;
}
I have tried to use MongoRepositories; however, I was not able to make the complex query.
How can one write such a query to a MongoDB from Spring Boot?
Thank you very much in advance.
If you can use embedded attributes, the class model should be:
#Document
#Data
#Builder
public class Person {
#Id
private String id;
private String firstName;
private String lastName;
private int age;
private List<Pet> pets;
}
#Data
#Builder
public class Pet {
private String name;
private int age;
private List<PetToy> toys;
}
#Data
#Builder
public class PetToy {
private String name;
}
The repository with the method that achieves what you want:
public interface PersonRepository extends MongoRepository<Person, String> {
List<Person> getByPetsToysName(String name);
}
The getByPetsToysName method basically navigate between Person's attributes Person->pets->toys->name. More info here.
An example
#Configuration
#EnableMongoRepositories
public class TestMongo implements CommandLineRunner {
private final PersonRepository repository;
public TestMongo(PersonRepository repository) {
this.repository = repository;
}
#Override
public void run(String... args) throws Exception {
repository.save(Person.builder()
.firstName("John")
.lastName("Doe")
.age(20)
.pets(Stream.of(Pet.builder()
.name("Ursa")
.age(1)
.toys(Stream.of(PetToy.builder()
.name("Teddy")
.build())
.collect(Collectors.toList()))
.build())
.collect(Collectors.toList()))
.build());
repository.save(Person.builder()
.firstName("Phillip")
.lastName("Larson")
.age(21)
.pets(Stream.of(Pet.builder()
.name("Bella")
.age(5)
.toys(Stream.of(PetToy.builder()
.name("Lolo")
.build())
.collect(Collectors.toList()))
.build())
.collect(Collectors.toList()))
.build());
List<Person> persons = repository.getByPetsToysName("Teddy");
System.out.println(persons.size());
List<Person> persons1 = repository.getByPetsToysName("Lolo");
System.out.println(persons1.size());
}
}
Logs:
find using query: { "pets.toys.name" : "Teddy" } fields: Document{{}} for class: class Person in collection: person
If you want more complex queries you can to take a look at the Spring Data MongoDB docs.