I have some Entities looks like this. Very abstract:
#Entity
class Man {
#Id
String name;
#OneToMany(fetch = FetchType.EAGER, mappedBy = "name", cascade = CascadeType.ALL)
List<Car> carList;
}
#IdClass(TypeId.class)
#Entity
class Car {
#Id
#NonNull
String name;
#Id
#NonNull
String class;
#ManyToOne(fetch = FetchType.EAGER, optional = false)
#JoinColumn(name = "class",
referencedColumnName = "class",
insertable = false,
updatable = false)
Engine engine;
}
#Entity
class Engine() {
#Id
#NonNull
String class;
String type;
Integer count;
}
class TypeId {
String name;
String class;
}
I need to construct #Query - select MAN with condition: if Engine types are equals, I need to take one Car with less Engine count. And return Man with only one Car if condition is met. Otherwise return Man with all cars.
Related
I am building an application that has a database of students, courses, and it also keeps track of all the courses that each student is taking,
I have an entity for Course and Student, and they have a one to many relationship with entity StudentCourses and an embeddable class of StudentCoursesID.
In the StudentCourse when I try to use the annotation AssociationOverride it gives me a problem saying
"Persistent type of override attribute "student" cannot be resolved"
"Persistent type of override attribute "course" cannot be resolved"
and
"Embedded ID class should not contain relationship mappings"
I dont understand if i did the mapping wrong or if there is a disconnection between my entities and classes.
Below I have each of the the entity starting with StudentCourses which is giving me issues.
StudentCourses
package jpa.entitymodels;
import javax.persistence.*;
#Entity
#Table(name = "student_courses")
#AssociationOverrides({
#AssociationOverride(name = "student", joinColumns = #JoinColumn(name = "sEmail")),
#AssociationOverride(name = "course", joinColumns = #JoinColumn(name = "cId"))
})
public class StudentCourses {
private StudentCoursesId id = new StudentCoursesId();
public StudentCourses() {
}
public StudentCourses(StudentCoursesId id) {
this.id = id;
}
#EmbeddedId
public StudentCoursesId getId() {
return id;
}
StudentCoursesId
package jpa.entitymodels;
import javax.persistence.Embeddable;
import javax.persistence.ManyToOne;
import java.io.Serializable;
#Embeddable
public class StudentCoursesId implements Serializable {
private static final long serialVersionUID = 1L;
private Student student;
private Course course;
public StudentCoursesId() {
}
#ManyToOne
public Student getStudent() {
return student;
}
public void setStudent(Student student) {
this.student = student;
}
#ManyToOne
public Course getCourse() {
return course;
}
Course
package jpa.entitymodels;
import javax.persistence.*;
import java.util.ArrayList;
import java.util.List;
#Entity
#Table(name = "course")
public class Course {
#Id
#Column(name = "id")
int cId;
#Column(name = "name")
String cName;
#Column(name = "instructor")
String cInstructorName;
#OneToMany(mappedBy = "id.course", fetch = FetchType.LAZY)
List<StudentCourses> studentCourses = new ArrayList<>();
Student
package jpa.entitymodels;
import java.util.ArrayList;
import java.util.List;
import javax.persistence.*;
#Entity
#Table(name="student")
public class Student {
#Id
#Column(name = "email")
String sEmail;
#Column(name = "name")
String sName;
#Column(name = "password")
String sPass;
#OneToMany(mappedBy = "id.student", fetch = FetchType.LAZY, cascade = CascadeType.ALL)
List<StudentCourses> studentCourses = new ArrayList<>();
The 'student' doesn't exist in StudentCourses which is why you get the error. Overrides you want to apply to the embeddable need to be defined on the embeddable mapping, not the StudentCourses class.
#Entity
#Table(name = "student_courses")
public class StudentCourses {
#Embedded
#AttributesOverride({
#AttributeOverride(name = "student", joinColumns = #JoinColumn(name = "sEmail")),
#AttributeOverride(nname = "course", joinColumns = #JoinColumn(name = "cId"))})
private EmbeddableClass embeddableClass;
public StudentCourses() {
}
}
JPA requires an ID class that has the simple pk types within it (or other nested composite PK classes, not relationships), requiring StudentCoursesId have a int/string property for the cId and sEmail. If you want to have mappings to course/student, maybe see the mapsId annotation or alternatively, I would map it like this:
#Entity
#Table(name = "student_courses")
#IdClass(StudentCoursesId.class)
public class StudentCourses {
#Id
#JoinColumn(name = "sEmail")
Student student;
#Id
#JoinColumn(name = "cId")
Course course;
}
public class StudentCoursesId implements Serializable {
private static final long serialVersionUID = 1L;
private String student;//Name matches id property in StudentCourses
private int course;
}
I want to use orderNumber in ProductRepository but I keep getting SQL error. I mapped both sides.
this is product entity.
#Entity
public class Product extends BaseEntity {
#Id
#GeneratedValue
#Column(name = "product_id")
private Long id;
#ManyToOne
#JoinColumn(name = "orderItem_id")
private OrderItem orderItem;
this is orderItem entity.
#Entity
public class OrderItem extends BaseEntity {
#Id
#GeneratedValue
#Column(name = "orderItem_id")
private Long id;
private String orderNumber
#OneToMany(mappedBy = "orderItem", cascade = CascadeType.ALL, orphanRemoval = true)
#Builder.Default
private List<Product> products = new ArrayList<Product>();
this is query in ProductRepository.
#Query(value = "SELECT * FROM OrderItem a, Product b WHERE a.orderItem_id = b.orderItem_id", nativeQuery = true)
Product findByOrderNumber(String orderNumber);
Alternatively, you can try query by a method as shown below, you don't need to use the #Query in this case.
ProductRepository
Product findByOrderItemOrderNumber(String orderNumber);
you can find more details here
Challenge:
I want to create a query that selects Topics that match both the keyword ID´s "Java" and "sql", the Topic with ID = 1 matches both keywords "Java" and "Sql.
I have implemented two simple entities Topic and Keyword. They have a bidirectional ManyToMany relationship:
#Entity
#Table(name = "Topic")
public class Topic implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "topicID")
private Long id;
#Column(name = "topicTitle")
private String title = "";
#ManyToMany
#JoinTable(name = "Join_Topic_Keyword",
joinColumns = #JoinColumn(name = "Topic_ID"),
inverseJoinColumns = #JoinColumn(name = "Keyword_ID"))
private Set<Keyword> keywords;
}
#Entity
#Table(name = "Keyword")
public class Keyword implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "keywordID")
private String id;
#ManyToMany(mappedBy = "keywords")
private Set<Topic> topics;
}
Here is the structure table.
And This is the result from Join_Topic_Keyword
Please I'm trying to find Quiz by Audit (using spring data jpa) and there must be an implicit search for the quizSubCategory which has a composite key, here are the classes :
Quiz entity:
#Entity
#Table(name = "quiz")
public class Quiz {
#EmbeddedId
private QuizCK id;
#Column
private String title;
#Column
private String status;
#Column
private String state;
#Column(name = "start_date")
private Date startDate;
#Column(name = "end_date")
private Date endDate;
#Column
private String reference;
#Column
private String results;
#Column(name = "is_default")
private boolean isDefault;
#ManyToOne
#JoinColumn(name = "id_audit")
private Audit audit;
#ManyToOne
#JoinColumns({
#JoinColumn(name = "id_quiz_sub_category", insertable = false, updatable = false),
#JoinColumn(name = "id_language", insertable = false, updatable = false)
})
private QuizSubCategory quizSubCategory;
#MapsId("idLanguage")
#ManyToOne
#JoinColumn(name="id_language", insertable = false, updatable = false)
private Language language;
public Quiz() {
}
// constructor & getters & setters
}
QuizSubCategory entity:
Entity
#Table(name = "quiz_sub_category")
public class QuizSubCategory implements Serializable {
#EmbeddedId
private QuizSubCategoryCK id;
private String libelle;
#ManyToOne
#JoinColumns({
#JoinColumn(name = "id_quiz_category", insertable = false, updatable = false),
#JoinColumn(name = "id_language", insertable = false, updatable = false)
})
private QuizCategory quizCategory;
#MapsId("idLanguage")
#ManyToOne
#JoinColumn(name="id_language", insertable = false, updatable = false)
private Language language;
public QuizSubCategory() {
super();
}
//constructor & getters & setters
}
QuizSubCategoryCK (primary key):
#Embeddable
public class QuizSubCategoryCK implements Serializable {
#Column(name = "id_quiz_sub_category", insertable = false, updatable = false)
#GeneratedValue(strategy = GenerationType.AUTO)
private int idQuizSubCategory;
#Column(name = "id_language", insertable = false, updatable = false)
private int idLanguage;
public QuizSubCategoryCK() {
}
public int getIdQuizSubCategory() {
return idQuizSubCategory;
}
public void setIdQuizSubCategory(int idQuizSubCategory) {
this.idQuizSubCategory = idQuizSubCategory;
}
public int getIdLanguage() {
return idLanguage;
}
public void setIdLanguage(int idLanguage) {
this.idLanguage = idLanguage;
}
}
QuizRepository :
public interface QuizRepository extends JpaRepository<Quiz,QuizCK> {
List<Quiz> findByAuditAndLanguage(Audit audit, Language language);
}
Controller:
#RequestMapping(value = "/quizzes/{auditId}", method = RequestMethod.GET)
public List<QuizBean> listQuizzes(#PathVariable int auditId){
AuditBean auditBean = auditService.getAudit(auditId);
LanguageBean languageBean = languageService.getLanguageById(1);
List<QuizBean> quizzes = quizService.findByAudit(AuditMapper.fromBean(auditBean),LanguageMapper.fromBean(languageBean));
return quizzes;
}
I'm getting the following error :
Unable to find jpa.entity.QuizSubCategory with id jpa.entity.QuizSubCategoryCK#79a59c48; nested exception is javax.persistence.EntityNotFoundException: Unable to find jpa.entity.QuizSubCategory with id jpa.entity.QuizSubCategoryCK#79a59c48
Any hints please ?!
I'm trying to have a localization table that is linked to from multiple tables.
I'm realizing that the problem is that I'm using the ID of Localization (eg Localization_Id) so I can't link to different localizations without some other key. Should I use a join table or some other sequential id in the database somehow? Not sure what the best approach is using JPA.
Thanks in advance.
#Entity
public class MyEntityWithLocalization {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
#OneToMany(fetch = FetchType.EAGER, cascade={CascadeType.ALL})
#JoinColumn(name="LOCALIZATION_KEY")
List<Localization> field1;
#OneToMany(fetch = FetchType.EAGER, cascade={CascadeType.ALL})
#JoinColumn(name="LOCALIZATION_KEY")
List<Localization> field2; //can't be unique from field one as it links to the MyEntityWithLocalization id.
#OneToMany(fetch = FetchType.EAGER, cascade={CascadeType.ALL})
#JoinColumn(name="LOCALIZATION_KEY")
List<Localization> field3; //can't be unique from field one as it links to the MyEntityWithLocalization id.
}
#Entity
public class Localization {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
String language;
String string;
public Localization(String language, String string) {
this.language = language;
this.string = string;
}
public Localization(){
}
}
This creates a localization_key in the localization table but that is just keyed to the ID of the MyEntityWithLocalization - it needs to be another unique value which makes me believe a join table may make sense in this case.
create table localization (
id number(19,0) not null,
language varchar2(255),
string varchar2(255),
localization_key number(19,0),
primary key (id)
);
Hmm. Why not just split the entity into constant and localizable part? Something like this:
#Entity
class MyEntity{
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
#OneToMany
#MapKeyColumn
Map<String, MyEntityLocalization> localizations;
}
#Embeddable
class MyEntityLocalization {
String field1;
String field2;
String field3;
}
Where the localizations field has the map from the language to the localization? The other way is using Hibernate-specific annotations:
#Entity
class MyEntityWithLocalization {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
#OneToMany
#MapKeyColumn(name="language")
#WhereJoinTable(clause = "key=1")
Map<String, String> field1;
#OneToMany
#MapKeyColumn(name="language")
#WhereJoinTable(clause = "key=2")
Map<String, String> field2;
}
#Entity
public class Localization {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
long id;
long key;
String language;
String string;
}