I want to display on my jsp something like this
CategoryParent1
-----Subcategory1
-----Subcategory2
CategoryParent2
-----Subcategory1
-----Subcategory2
In which way i can solve it? Does spring-mvc has some library for it? Or i must use some external libraries?
I have a Category model
#Entity
public class Category {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
private String name;
#ManyToOne
private Category parentCategory;
#OneToMany(mappedBy = "parentCategory", cascade = CascadeType.ALL)
private List<Category> childCategories = new ArrayList<>();
public Category() {
}
public Category(String name){
this.name = name;
}
public Category(String name, Category parentCategory) {
this.name = name;
this.parentCategory = parentCategory;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Category getParentCategory() {
return parentCategory;
}
public void setParentCategory(Category parentCategory) {
this.parentCategory = parentCategory;
}
public List<Category> getChildCategories() {
return childCategories;
}
public void setChildCategories(List<Category> childCategories) {
this.childCategories = childCategories;
}
}
I have done the similar task but with recursive query. Here is the
link
If you don't want to use recursive query. here is what you need to do.
Eagerly fetch child categories (see hibernate eager fetch| lazy load)
Remove the "sub query" which is inside the "main query" and remove the recursing statement of a function
If you have successfully created relationship, you can just get its children categories by using your "getchildrencategories" method.
It is your choice whether you use recursive function or not.
And do not use List its better to use Set:
#OneToMany(fetch = FetchType.EAGER, mappedBy="parentCategory", cascade=CascadeType.REMOVE, orphanRemoval=true )
private Set<Categories> childCategories = new HashSet<Categories>();
Related
I Have a rest controller that is not de-serializing the array type in json..
#PostMapping()
#ResponseBody
public ResponseEntity<Team> createteam(#RequestBody Team team) throws JsonProcessingException {
Team savedTeam = teamService.createTeam(team);
return new ResponseEntity<Team>(savedTeam, HttpStatus.CREATED);
}
below is my entity class.
#Entity
#JsonIdentityInfo(generator = IntSequenceGenerator.class)
public class Team {
#Id
#GeneratedValue
private Long id;
private String name;
#OneToMany(mappedBy = "team", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private List<Developer> developers;
public Team(String name, List<Developer> developer) {
super();
this.name = name;
this.developers = developer;
}
public Team() {
super();
}
public List<Developer> getDeveloper() {
return developers;
}
public void setDeveloper(List<Developer> developer) {
this.developers = developer;
}
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;
}
}
and my other entity..
package com.demo.springbootdemo.entity;
#Entity
#JsonIdentityInfo(generator = IntSequenceGenerator.class)
public class Developer {
#Id
#GeneratedValue
private Long id;
#ManyToOne
private Team team;
private Long phone;
private String name;
public Developer() {
super();
}
public Developer(Team team, Long phone, String name) {
super();
this.team = team;
this.phone = phone;
this.name = name;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public Team getTeam() {
return team;
}
public void setTeam(Team team) {
this.team = team;
}
public Long getPhone() {
return phone;
}
public void setPhone(Long phone) {
this.phone = phone;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
below is my JSON payload, which returns null "developers" when i call the post method.i have tried changing the number of properties in json payload but, still i am not able to figure out why my json is not de-serilaized to List of developers..
{
"id": 1004,
"name": "claim",
"developers": [
{
"id" :1,
"phone": 9092123,
"name": "raina"
}
]
}
I am not sure what Deserializer are you using, but with the Jackson ObjectMapper I solved it changing the method names of the getter and setter for the developers properties: they should be called setDevelopers and getDevelopers. In your code they are called setDeveloper and getDeveloper, without the final S.
To avoid problem like these, I just add Lombok as a dependency and it takes care of creating setters and getters.
With Lombok your Team class would look like this:
// ... more imports here...
import lombok.Data;
#Data
#JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class)
public class Team {
#Id
#GeneratedValue
private Long id;
private String name;
#OneToMany(mappedBy = "team", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private List<Developer> developers;
}
You may need to add more Lombok annotations for generating constructor methods according to your needs.
I'm trying to execute an HQL for a many to many mapping in hibernate and getting a weird issue:
Caused by: java.sql.SQLSyntaxErrorException: Unknown columnallowedage1_.allowedAgencies_organization_id' in 'on clause'
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:120)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
Basically, I have two tables, Reservation_Reason_Type and Agency. I need to do a many to many before them. I believe I'm doing everything correctly, but when I run the code, its giving me this unknown column issue. Not sure why it is doing allowedage1_allowedAgencies_organization_id. It is including the variable name in generated HQL as well.
Below are the mapped classes:
Agency.java
#Entity
#Table(name = "AGENCY")
public class Agency {
#Id
#Column(name="organization_id")
private int id;
#Column(name="name")
private String name;
#Column(name="acronym")
private String acronym;
#ManyToMany(fetch = FetchType.EAGER, cascade = CascadeType.ALL, mappedBy = "allowedAgencies")
private Collection<ReservationReasonType> allowedReservations = new ArrayList<ReservationReasonType>();
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getAcronym() {
return acronym;
}
public void setAcronym(String acronym) {
this.acronym = acronym;
}
public Collection<ReservationReasonType> getAllowedReservations() {
return allowedReservations;
}
public void setAllowedReservations(Collection<ReservationReasonType> allowedReservations) {
this.allowedReservations = allowedReservations;
}
}
ReservationReasonType.java
#Entity
#Table(name = "RESERVATION_REASON_TYPE")
public class ReservationReasonType {
#Id
#Column(name = "reservation_reason_type_id")
private int id;
#Column(name = "description")
private String description;
#Column(name = "reservation_reason_type_code")
private String code;
#ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
#JoinTable(name="RES_AGENCY", joinColumns={#JoinColumn(referencedColumnName="reservation_reason_type_id")}
, inverseJoinColumns={#JoinColumn(referencedColumnName="organization_id")})
private Collection<Agency> allowedAgencies = new ArrayList<Agency>();
public ReservationReasonType(int id, String description, String code) {
this.setId(id);
this.setDescription(description);
this.setCode(code);
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public Collection<Agency> getAllowedAgencies() {
return allowedAgencies;
}
#ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
#JoinTable(name="RES_AGENCY", joinColumns={#JoinColumn(referencedColumnName="reservation_reason_type_id")}
, inverseJoinColumns={#JoinColumn(referencedColumnName="organization_id")})
//Set<Agency> allowedAgencies = new HashSet<Agency>();
public void setAllowedAgencies(Collection<Agency> allowedAgencies) {
this.allowedAgencies = allowedAgencies;
}
}
Below is the query that I'm using for HQL:
String query = "select rrt from ReservationReasonType as rrt join rrt.allowedAgencies age where age.acronym = :agencyAcronym)";
Below is the generated HQL which won't run because of the unknown columns:
Hibernate:
select
reservatio0_.reservation_reason_type_id as reservat1_2_,
reservatio0_.reservation_reason_type_code as reservat2_2_,
reservatio0_.description as descript3_2_
from
RESERVATION_REASON_TYPE reservatio0_
inner join
RES_AGENCY allowedage1_
on reservatio0_.reservation_reason_type_id=allowedage1_.allowedReservations_reservation_reason_type_id
inner join
AGENCY agency2_
on allowedage1_.allowedAgencies_organization_id=agency2_.organization_id
where
agency2_.acronym=?
I double checked whether I'm doing the mapping right, and I think there isn't any issue with that. One thing I'm not sure of is that I'm using Hibernate 3.0, hibernate jpa 2.0, and mysql 8.0.19. Not sure if it can be an issue with that?
Need help.
UPDATE:
For a temporary solution, I added the below two columns to the RES_AGENCY table and its working, but this is just a bandaid. Still trying to figure out what can be a proper solution:
allowedReservations_reservation_reason_type_id
allowedAgencies_organization_id
I have the following scenario:
I have a Student class and students table.
I have Course class and courses table.
Every student and course have unique ID.
I would like to put a List into the Student class which is mapped by courses IDs.
I have tried a lot of annotations and relations but nothing succeeded
#Entity
#Table(name = "courses")
public class Course {
private long id;
private String name;
public Course() {
}
public Course(String name, int size) {
this.name = name;
this.size = size;
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
#Column(name = "name", nullable = false)
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
#Entity
#Table(name = "students")
public class Student {
private long id;
private String name;
#OneToMany(cascade = CascadeType.ALL)
private List<Course> courses = new ArrayList<>();
public Student() {
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
#Column(name = "name", nullable = false)
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public List<Course> getCourses() {
return courses;
}
public void setCourses(List<Course> courses) {
this.courses = courses;
}
}
Can you help me hot to achieve that because i am a little newbie into the spring
Use the following when declaring one to many relation
#Column(name="course_id")
private Set<Course> courses;
You need to use OneToMany annotation.
#OneToMany(mappedBy = "students", cascade = CascadeType.ALL)
private List<Course> courses;
You need to give your list a type. For instance
List<Courses> courseList = new ArrayList<>();
The jhipster doesn't support create many to many relationships with extra fields.
What is the best way to create many to many association with extra columns in jhispter? Should i create a two one-to-many relationship with extra fields?
Using JHipster Domain Language (JDL), a #ManytoMany holding extra properties (columns) can be easily achieved using an association entity and two ManyToOne relationships. See below:
entity Foo{
...
}
entity Bar{
...
}
entity FooBarAssociation{
extraProperty1 String
extraProperty2 String
...
}
relationship ManyToOne {
FooBarAssociation{foo} to Foo{bars}
FooBarAssociation{bar} to Bar{foos}
}
You will have to do it manually.
this post describes how: https://hellokoding.com/jpa-many-to-many-extra-columns-relationship-mapping-example-with-spring-boot-maven-and-mysql/
In general, as #Antares42 said, you should create an entity for the Many-To-Many table like so:
first entity:
#Entity
public class Book{
private int id;
private String name;
private Set<BookPublisher> bookPublishers;
public Book() {
}
public Book(String name) {
this.name = name;
bookPublishers = new HashSet<>();
}
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#OneToMany(mappedBy = "book", cascade = CascadeType.ALL, orphanRemoval = true)
public Set<BookPublisher> getBookPublishers() {
return bookPublishers;
}
public void setBookPublishers(Set<BookPublisher> bookPublishers) {
this.bookPublishers = bookPublishers;
}
}
secound entity:
#Entity
public class Publisher {
private int id;
private String name;
private Set<BookPublisher> bookPublishers;
public Publisher(){
}
public Publisher(String name){
this.name = name;
}
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#OneToMany(mappedBy = "publisher")
public Set<BookPublisher> getBookPublishers() {
return bookPublishers;
}
public void setBookPublishers(Set<BookPublisher> bookPublishers) {
this.bookPublishers = bookPublishers;
}
}
Join table entity:
#Entity
#Table(name = "book_publisher")
public class BookPublisher implements Serializable{
private Book book;
private Publisher publisher;
private Date publishedDate;
#Id
#ManyToOne
#JoinColumn(name = "book_id")
public Book getBook() {
return book;
}
public void setBook(Book book) {
this.book = book;
}
#Id
#ManyToOne
#JoinColumn(name = "publisher_id")
public Publisher getPublisher() {
return publisher;
}
public void setPublisher(Publisher publisher) {
this.publisher = publisher;
}
#Column(name = "published_date")
public Date getPublishedDate() {
return publishedDate;
}
public void setPublishedDate(Date publishedDate) {
this.publishedDate = publishedDate;
}
}
This entity describes the relationship between Book and Publisher and the extra field is published_date
Let's say you have entities like Movie, Rater and needs a join table Ratings. You can write a JDL script like the following:
entity Movie { title String}
entity Rater { name String}
entity Rating { value Integer} //the extra field
relationship ManyToMany {
Rating{rater(name)} to Rater,
Rating{movie(title)} to Movie
}
save it in file.jdl in the project folder, open cmd type
jhipster import-jdl file.jdl
and you have everything
I have model. there is this part:
model was mapped by jpa annotations.Everywhere I use fetchType = EAGER. If I load vacancy from database, I have 2 duplicates status_for_vacancy objects.
I use property hbm2ddl.auto = update.
If I make new schema of database and fill data, I haven't duplicates status_for_vacancy objects.
It really?
code:
vacancy:
#Entity
#Table(name = "vacancy")
#XmlRootElement(name="vacancy")
public class Vacancy {
private List<VacancyStatus> statusList = new LinkedList<VacancyStatus>();
#OneToMany(mappedBy = "vacancy", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
public List<VacancyStatus> getStatusList() {
return statusList;
}
public void setStatusList(List<VacancyStatus> statusList) {
this.statusList = statusList;
}
}
status_for_vacancy:
#Entity
#Table(name = "status_for_vacancy")
public class StatusForVacancy extends AbstractStatus {
public StatusForVacancy() {
super();
}
public StatusForVacancy(Integer id, String name) {
super(id, name);
}
}
#MappedSuperclass
#XmlRootElement
public abstract class AbstractStatus {
private Integer id;
private String name;
public AbstractStatus() {
super();
}
public AbstractStatus(String name) {
super();
this.name = name;
}
public AbstractStatus(Integer id, String name) {
super();
this.id = id;
this.name = name;
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column (name ="id")
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#Column(name = "name")
#NotEmpty
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
vacancy_status:
#Entity
#Table(name = "vacancy_status")
public class VacancyStatus extends AbstractHistoryStatus {
private Vacancy vacancy;
private StatusForVacancy status;
public VacancyStatus() {
super();
}
public VacancyStatus(Integer id, User author, Date date,
Vacancy vacancy, StatusForVacancy status) {
super(id, author, date);
this.vacancy = vacancy;
this.status = status;
}
#ManyToOne
#JoinColumn(name = "vacancy_id")
public Vacancy getVacancy() {
return vacancy;
}
public void setVacancy(Vacancy vacancy) {
this.vacancy = vacancy;
}
#ManyToOne
#JoinColumn(name = "status_id")
public StatusForVacancy getStatus() {
return status;
}
public void setStatus(StatusForVacancy status) {
this.status = status;
}
}
#MappedSuperclass
public abstract class AbstractHistoryStatus {
private Integer id;
private User author;
private Date date;
public AbstractHistoryStatus() {
}
public AbstractHistoryStatus(Integer id, User author, Date date) {
super();
this.id = id;
this.author = author;
this.date = date;
}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#ManyToOne
public User getAuthor() {
return author;
}
public void setAuthor(User author) {
this.author = author;
}
#Column(name="creation_date")
public Date getDate() {
return date;
}
public void setDate(Date date) {
this.date = date;
}
}
It is all mapping code for these entities.
in debugger:
both id==500 ==> hibernate understand, that it is same objects.
I try add all data from old database to new database - I get old error(
I fix cause of appearance of this problem. It appearances if I add record to note table:
I highly recommend you write equals() and hashCode() methods. The standard equals()/hashCode() implement referential equality (do 2 objects reference the same memory location). So if hibernate has 2 of the 'same' object in memory, but they don't reference the same memory location then you will see the object show up twice. But if you implement equals() based on primary key being equal, then even if there are two copies of the same object in memory, Hibernate won't give you duplicates.
See the JPA spec:
2.4 Primary Keys and Entity Identity
Every entity must have a primary key. ... The value of its primary key
uniquely identifies an entity instance within a persistence context
and to EntityManager operations
Also see this SO post.