There are the entities Cookbook, Recipe. It's a ManyToMany relation: a cookbook can have multiple recipes and a recipe can be assigned to multiple cookbooks. So I added the entity CookbookRecipe and connected the entities as OneToMany.
Where to put a method to add/remove the relation between Cookbook and Recipe - does this method has to add a new CookbookRecipe and add this CookbookRecipe to Cookbook and Recipe?
In my understanding I would expect a
public void addRecipe(Recipe recipe) {
CookbookRecipe relation = new CookbookRecipe();
relation.setCookbook(this);
relation.setRecipe(recipe);
this.cookbookRecipes.add( relation );
}
Is this the right direction?
Would I add this method to the Cookbook DAO or Recipe DAO or put this into a service?
#Entity
public class Cookbook {
private Integer id;
private String title;
private Collection<CookbookRecipe> cookbookRecipes;
private Collection<CookbookSortlevel> cookbookSortlevels;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#Basic
#Column(name = "title")
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Cookbook cookbook = (Cookbook) o;
if (id != null ? !id.equals(cookbook.id) : cookbook.id != null) return false;
if (title != null ? !title.equals(cookbook.title) : cookbook.title != null) return false;
return true;
}
#Override
public int hashCode() {
int result = id != null ? id.hashCode() : 0;
result = 31 * result + (title != null ? title.hashCode() : 0);
return result;
}
#OneToMany(mappedBy = "cookbook", fetch = FetchType.EAGER)
public Collection<CookbookRecipe> getCookbookRecipes() {
return cookbookRecipes;
}
public void setCookbookRecipes(Collection<CookbookRecipe> cookbookRecipes) {
this.cookbookRecipes = cookbookRecipes;
}
#OneToMany(mappedBy = "cookbook")
public Collection<CookbookSortlevel> getCookbookSortlevels() {
return cookbookSortlevels;
}
public void setCookbookSortlevels(Collection<CookbookSortlevel> cookbookSortlevels) {
this.cookbookSortlevels = cookbookSortlevels;
}
}
#Entity
#Table(name = "cookbook_recipe", schema = "", catalog = "")
public class CookbookRecipe {
private Integer id;
private Recipe recipe;
private Cookbook cookbook;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
CookbookRecipe that = (CookbookRecipe) o;
if (id != null ? !id.equals(that.id) : that.id != null) return false;
return true;
}
#Override
public int hashCode() {
int result = id != null ? id.hashCode() : 0;
return result;
}
#ManyToOne
#JoinColumn(name = "recipe_id", referencedColumnName = "id")
public Recipe getRecipe() {
return recipe;
}
public void setRecipe(Recipe recipe) {
this.recipe = recipe;
}
#ManyToOne
#JoinColumn(name = "cookbook_id", referencedColumnName = "id", nullable=false,insertable=false,updatable=false )
public Cookbook getCookbook() {
return cookbook;
}
public void setCookbook(Cookbook cookbook) {
this.cookbook = cookbook;
}
}
#Entity
public class Recipe {
private Integer id;
private String title;
private String text;
private Collection<RecipeIngredient> recipeIngredients;
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
#Basic
#Column(name = "title")
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
#Basic
#Column(name = "text")
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Recipe recipe = (Recipe) o;
if (id != null ? !id.equals(recipe.id) : recipe.id != null) return false;
if (title != null ? !title.equals(recipe.title) : recipe.title != null) return false;
if (text != null ? !text.equals(recipe.text) : recipe.text != null) return false;
return true;
}
#Override
public int hashCode() {
int result = id != null ? id.hashCode() : 0;
result = 31 * result + (title != null ? title.hashCode() : 0);
result = 31 * result + (text != null ? text.hashCode() : 0);
return result;
}
#OneToMany(mappedBy = "recipe")
public Collection<RecipeIngredient> getRecipeIngredients() {
return recipeIngredients;
}
public void setRecipeIngredients(Collection<RecipeIngredient> recipeIngredients) {
this.recipeIngredients = recipeIngredients;
}
}
Are there any github projects handling this you could suggest?
This is, for me, the right direction. The code looks good
I think you should add it in the CookBookDAO because the Cookbook contains Recipes not the opposite
Related
I want to manage Persons, Teams and their Membership with Spring Data JPA.
The following test (whenAddingANewTeamTroughPerson)
passes when I use entityManager.persist(alex);
throws an exception if I use personRepository.save(alex);
Why? In the latter case I get the following exception:
org.springframework.dao.InvalidDataAccessApiUsageException: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: hello.data.model.Person; nested exception is java.lang.IllegalStateException: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: hello.data.model.Person
It behaves as CASCADE is not set properely. But it must be correct, since it works with the entityManager.
PersonRepositoryTest:
#RunWith(SpringRunner.class)
#DataJpaTest
public class PersonRepositoryTest {
#Autowired
private TestEntityManager entityManager;
#Autowired
private PersonRepository personRepository;
#Autowired
private TeamRepository teamRepository;
#Test
public void whenFindOne_thenReturnPerson() {
// given
Person alex = new Person("alex");
entityManager.persist(alex);
entityManager.flush();
// when
Person found = personRepository.findOne(alex.getId());
// then
assertThat(found.getName(), equalToIgnoringWhiteSpace(alex.getName()));
}
#Test
public void whenAddingANewTeamTroughPerson_thenNoException() {
// given
Person alex = new Person("alex");
Team t = new Team("team");
alex.addTeam(t, "integrationTest", new Date());
personRepository.save(alex);
//entityManager.persist(alex);
// when
Person found = personRepository.findOne(alex.getId());
// then
assertThat(found.getTeams().size(), is(1));
}
}
PersonRepository:
public interface PersonRepository extends CrudRepository<Person, Integer> {}
Person:
#Entity
public class Person {
private static final Logger LOG = LoggerFactory.getLogger(Person.class);
private final IntegerProperty id = new SimpleIntegerProperty(this, "id");
private final StringProperty name = new SimpleStringProperty(this, "name");
private Set<PersonTeam> personTeams = new LinkedHashSet<>();
private ListProperty<Team> teams = new SimpleListProperty<>(this, "teams", FXCollections.observableArrayList());
public Person(String s) {
this.name.set(s);
}
public Person() {}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
public Integer getId() {
return id.get();
}
public void setId(Integer id) {
this.id.set(id);
}
public IntegerProperty idProperty() {
return id;
}
#Basic
#Column(name = "name")
public String getName() {
return name.get();
}
public void setName(String name) {
this.name.set(name);
}
public StringProperty nameProperty() {
return name;
}
#OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.person", cascade=CascadeType.ALL, orphanRemoval = true)
public Set<PersonTeam> getPersonTeams() {
return personTeams;
}
public void setPersonTeams(Set<PersonTeam> personTeams) {
this.personTeams = personTeams;
teams.setAll(personTeams.stream().map(PersonTeam::getTeam).collect(Collectors.toList()));
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Person person = (Person) o;
if (getId() != null ? !getId().equals(person.getId()) : person.getId() != null) return false;
if (getName() != null ? !getName().equals(person.getName()) : person.getName() != null) return false;
return true;
}
#Override
public int hashCode() {
int result = id != null ? id.hashCode() : 0;
result = 31 * result + (getName() != null ? getName().hashCode() : 0);
return result;
}
/**
* Returns an Observable List that must remain unchanged.
* Unfortunately there is no RO Observable List Interface to refer to.
*/
#Transient
public ObservableList<Team> getTeams() {
return teams.get();
}
#Transient
public ReadOnlyListProperty<Team> teamsProperty() {
return teams;
}
public void addTeam(Team team, String createdBy, Date createdDate) {
final PersonTeam personTeam = new PersonTeam(this, team);
personTeam.setCreatedBy(createdBy);
personTeam.setCreatedDate(createdDate);
if( !personTeams.add(personTeam) ) {
LOG.error("Failed to add personTeam " + personTeam + " to collection personTeams " + personTeams);
}
if( !team.getPersonTeams().add( personTeam ) ) {
LOG.error("Failed to add personTeam " + personTeam + " to collection team.getPersonTeams " + team.getPersonTeams());
}
teams.setAll(personTeams.stream().map(PersonTeam::getTeam).collect(Collectors.toList()));
}
public void removeTeam(Team team) {
PersonTeam personTeam = new PersonTeam( this, team );
team.getPersonTeams().remove( personTeam );
personTeams.removeIf( pt -> pt.getTeam() == team );
personTeam.setPerson( null );
personTeam.setTeam( null );
teams.setAll(personTeams.stream().map(PersonTeam::getTeam).collect(Collectors.toList()));
}
/*
The method is not intended to be used in the GUI.
Use the {#link GUIRepresentable} interface instead.
*/
#Override
public String toString() {
return name.getValue();
}
}
PersonTeam:
#Entity
#Table(name = "person_team")
#AssociationOverrides({
#AssociationOverride(name = "pk.person",
joinColumns = #JoinColumn(name = "PERSON_ID")),
#AssociationOverride(name = "pk.team",
joinColumns = #JoinColumn(name = "TEAM_ID")) })
public class PersonTeam implements java.io.Serializable {
private PersonTeamPk pk = new PersonTeamPk();
private Date createdDate;
private String createdBy;
public PersonTeam() {
}
public PersonTeam(Person person, Team team) {
this.pk.setPerson(person);
this.pk.setTeam(team);
}
#EmbeddedId
public PersonTeamPk getPk() {
return pk;
}
public void setPk(PersonTeamPk pk) {
this.pk = pk;
}
#Transient
public Person getPerson() {
return getPk().getPerson();
}
public void setPerson(Person person) {
getPk().setPerson(person);
}
#Transient
public Team getTeam() {
return getPk().getTeam();
}
public void setTeam(Team team) {
getPk().setTeam(team);
}
#Temporal(TemporalType.DATE)
#Column(name = "CREATED_DATE", nullable = false, length = 10)
public Date getCreatedDate() {
return this.createdDate;
}
public void setCreatedDate(Date createdDate) {
this.createdDate = createdDate;
}
#Column(name = "CREATED_BY", nullable = false, length = 10)
public String getCreatedBy() {
return this.createdBy;
}
public void setCreatedBy(String createdBy) {
this.createdBy = createdBy;
}
public boolean equals(Object o) {
if (this == o)
return true;
if (o == null || getClass() != o.getClass())
return false;
PersonTeam that = (PersonTeam) o;
if (getPk() != null ? !getPk().equals(that.getPk())
: that.getPk() != null)
return false;
return true;
}
public int hashCode() {
return (getPk() != null ? getPk().hashCode() : 0);
}
}
PersonTeamPk:
#Embeddable
public class PersonTeamPk implements java.io.Serializable {
private Person person;
private Team team;
#ManyToOne(cascade = CascadeType.ALL)
public Person getPerson() {
return person;
}
public void setPerson(Person person) {
this.person = person;
}
#ManyToOne(cascade = CascadeType.ALL)
public Team getTeam() {
return team;
}
public void setTeam(Team team) {
this.team = team;
}
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
PersonTeamPk that = (PersonTeamPk) o;
if (person != null ? !person.equals(that.person) : that.person != null) return false;
if (team != null ? !team.equals(that.team) : that.team != null)
return false;
return true;
}
public int hashCode() {
int result;
result = (person != null ? person.hashCode() : 0);
result = 31 * result + (team != null ? team.hashCode() : 0);
return result;
}
}
Team:
#Entity
public class Team implements Serializable, Comparable<Team> {
private final IntegerProperty id = new SimpleIntegerProperty(this, "id");
private final StringProperty name = new SimpleStringProperty(this, "name");
private Set<PersonTeam> personTeams = new LinkedHashSet<>();
public Team(String s) {
this.name.set(s);
}
public Team() {}
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
public Integer getId() {
return id.get();
}
public void setId(Integer id) {
this.id.set(id);
}
public IntegerProperty idProperty() {
return id;
}
#Basic
#Column(name = "name")
public String getName() {
return name.get();
}
public void setName(String name) {
this.name.set(name);
}
public StringProperty nameProperty() {
return name;
}
#OneToMany(fetch = FetchType.LAZY, mappedBy = "pk.team", orphanRemoval = true, cascade = CascadeType.ALL)
public Set<PersonTeam> getPersonTeams() {
return personTeams;
}
public void setPersonTeams(Set<PersonTeam> personTeams) {
this.personTeams = personTeams;
}
public static Callback<Team, Observable[]> extractor() {
return (Team p) -> new Observable[]{p.nameProperty()};
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Team team = (Team) o;
if (getId() != null ? !getId().equals(team.getId()) : team.getId() != null) return false;
if (getName() != null ? !getName().equals(team.getName()) : team.getName() != null) return false;
return true;
}
#Override
public int hashCode() {
int result = id != null ? id.hashCode() : 0;
result = 31 * result + (getName() != null ? getName().hashCode() : 0);
return result;
}
#Override
public String toString() {
return name.getValue();
}
#Override
public int compareTo(Team o) {
return Integer.compare(getId(), o.getId());
}
}
When a parent entity is persisted/merged via saveAndFlush, it tries to insert a new record for the child entity instead of finding/merging the existing record. This causes a SQLIntegrityConstraintViolationException error. I have also tried pulling the existing entity directly via the DAO, setting that to be the field in the parent entity, and then saving and flushing, and it still tries to insert a new record for the child entity field.
Any help is greatly appreciated!
Child Entity
#Entity
#Table(name = "DROPDOWN_TYPE", uniqueConstraints = {
#UniqueConstraint(columnNames = { "DROPDOWN_TYPE_TXT" }, name = "DROPDOWN_TYPE_TXT_UK") })
public class DropdownType {
#Id
#Column(name = "DROPDOWN_TYPE_TXT")
private String text;
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
DropdownType that = (DropdownType) o;
return text.equals(that.text);
}
#Override
public int hashCode() {
return text.hashCode();
}
}
Parent Entity
#Entity
#Table(name = "DROPDOWN", uniqueConstraints = {
#UniqueConstraint(columnNames = { "DROPDOWN_TXT", "DROPDOWN_TYPE_TXT" }, name = "DROPDOWN_UK") })
#JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
public class Dropdown {
#Id
#GeneratedValue(strategy = GenerationType.AUTO, generator = "DROPDOWN_OPTION_ID_GENERATOR")
#SequenceGenerator(allocationSize = 1, name = "DROPDOWN_OPTION_ID_GENERATOR", sequenceName = "DROPDOWN_OPTION_ID_SQ")
#Column(name = "DROPDOWN_OPTION_ID")
private Long id;
#ManyToOne(cascade = { CascadeType.MERGE, CascadeType.PERSIST })
#JoinColumn(name = "DROPDOWN_TYPE_TXT", foreignKey = #ForeignKey(name = "DROPDOWN_TYPE_TXT_FK"))
private DropdownType dropdownType;
#Column(name = "DROPDOWN_TXT")
private String text;
#Column(name = "ACTIVE_FLG")
private Boolean active;
#Column(name = "LEGACY_FLG")
private Boolean legacy;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public DropdownType getDropdownType() {
return dropdownType;
}
public void setDropdownType(DropdownType dropdownType) {
this.dropdownType = dropdownType;
}
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
public Boolean isActive() {
return active;
}
public void setActive(Boolean active) {
this.active = active;
}
public Boolean isLegacy() {
return legacy;
}
public void setLegacy(Boolean legacy) {
this.legacy = legacy;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
Dropdown dropdown = (Dropdown) o;
return dropdownType.equals(dropdown.dropdownType) && text.equals(dropdown.text);
}
#Override
public int hashCode() {
int result = dropdownType != null ? dropdownType.hashCode() : 0;
result = 31 * result + (text != null ? text.hashCode() : 0);
return result;
}
}
If you are using hibernate as your JPA provider, be careful when you override equals and hashcode -- see this post
It may be, that your JPA provider does not consider your entities to be equal as loaded entities can be some CGLIB proxies in reality (probably better to use instanceof than to compare classes).
I'm trying to execute an IN query with by using Spring Data. My model looks like this:
#Entity
#Table(name = "customer", schema = "public", catalog = "postgres")
public class CustomerEntity {
private int id;
private String name;
private int balance;
private String bankId;
#Id
#Column(name = "id")
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
#Basic
#Column(name = "name")
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#Basic
#Column(name = "balance")
public int getBalance() {
return balance;
}
public void setBalance(int balance) {
this.balance = balance;
}
#Basic
#Column(name = "bank_id")
public String getBankId() {
return bankId;
}
public void setBankId(String bankId) {
this.bankId = bankId;
}
And my repository interface looks like this:
#Repository
public interface TransactionsRepository extends JpaRepository<TransactionsEntity, Long> {
List<TransactionsEntity> findByCustomerIdIn(List<CustomerEntity> customerEntities);
}
The problem is that when I try to execute this code
List<TransactionsEntity> transactionsEntitiesList = transactionsRepository.findByCustomerIdIn(customerEntitiesList);
I get this exception:
Caused by: org.springframework.dao.InvalidDataAccessApiUsageException: Parameter value element [org.example.domain.admin.CustomerEntity#6a1a2a4] did not match expected type [java.lang.String (n/a)]; nested exception is java.lang.IllegalArgumentException: Parameter value element [org.example.domain.admin.CustomerEntity#6a1a2a4] did not match expected type [java.lang.String (n/a)]
Update: TransactionsEntity.class:
#Entity
#Table(name = "transactions", schema = "public", catalog = "postgres")
public class TransactionsEntity {
private String id;
private String amount;
private String customerId;
#Id
#Column(name = "id")
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
#Basic
#Column(name = "amount")
public String getAmount() {
return amount;
}
public void setAmount(String amount) {
this.amount = amount;
}
#Basic
#Column(name = "customer_id")
public String getCustomerId() {
return customerId;
}
public void setCustomerId(String customerId) {
this.customerId = customerId;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;
TransactionsEntity that = (TransactionsEntity) o;
if (id != null ? !id.equals(that.id) : that.id != null) return false;
if (amount != null ? !amount.equals(that.amount) : that.amount != null) return false;
if (customerId != null ? !customerId.equals(that.customerId) : that.customerId != null) return false;
return true;
}
#Override
public int hashCode() {
int result = id != null ? id.hashCode() : 0;
result = 31 * result + (amount != null ? amount.hashCode() : 0);
result = 31 * result + (customerId != null ? customerId.hashCode() : 0);
return result;
}
}
As it says in the exception Spring expects a String because your customer_id in your TransactionEntity is a String, but you are inputting a CustomerEntity. Instead you should input a List<String> with the list of your customer ids.
Btw shouldn't your customer_id be an int assuming you set it to the id of your CustomerEntity?
Then you could do something like
List<Integer> customerIds = customerEntitiesList.stream().map(CustomerEntity::getId).collect(Collectors.toList());
I have an EJB application in where I am using Entity beans for database. I have to Entity beans having unidirectional one to one relation, JobPositionEntity and CandidateEntity.
Here is CandidateEntity
#Entity
public class CandidateEntity extends BaseEntity {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private Long meritNumber;
private String seatNumber;
private String candidateName;
private String gender;
public Long getMeritNumber() {
return meritNumber;
}
public void setMeritNumber(Long meritNumber) {
this.meritNumber = meritNumber;
}
public String getSeatNumber() {
return seatNumber;
}
public void setSeatNumber(String seatNumber) {
this.seatNumber = seatNumber;
}
public String getCandidateName() {
return candidateName;
}
public void setCandidateName(String candidateName) {
this.candidateName = candidateName;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
#Override
public Long getId() {
return id;
}
#Override
public void setId(Long id) {
this.id = id;
}
#Override
public int hashCode() {
int hash = 0;
hash += (id != null ? id.hashCode() : 0);
return hash;
}
#Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof CandidateEntity)) {
return false;
}
CandidateEntity other = (CandidateEntity) object;
if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
return false;
}
return true;
}
#Override
public String toString() {
return "com.nisheeth.config.ejb.entity.CandidateEntity[ id=" + id + " ]";
}
}
Here is JobPositionEntity
#Entity
public class JobPositionEntity extends BaseEntity {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
#OneToOne(fetch = FetchType.EAGER, orphanRemoval = true, cascade = CascadeType.ALL)
private CandidateEntity candidate;
#ManyToOne(fetch = FetchType.EAGER)
private SeasonEntity season;
public SeasonEntity getSeason() {
return season;
}
public void setSeason(SeasonEntity season) {
this.season = season;
}
public CandidateEntity getCandidate() {
return candidate;
}
public void setCandidate(CandidateEntity candidate) {
this.candidate = candidate;
}
#Override
public Long getId() {
return id;
}
#Override
public void setId(Long id) {
this.id = id;
}
#Override
public int hashCode() {
int hash = 0;
hash += (id != null ? id.hashCode() : 0);
return hash;
}
#Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof JobPositionEntity)) {
return false;
}
JobPositionEntity other = (JobPositionEntity) object;
if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
return false;
}
return true;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
#Override
public String toString() {
return "com.nisheeth.config.ejb.entity.JobPositionEntity[ id=" + id + " ]";
}
}
I want to select candidates which are not in JobPositionEntity. I have this query which did not work for me:
select ce.candidateName, ce.id from JobPositionEntity jp left join jp.candidate ce where ce <> null
Can anyone help write this query? Thanks in advance.
you can use a SubQuery
select c from Candidate c where c.id not in
(select jp.candidate.id from JobPositionEntity jp)
for more information:
https://docs.jboss.org/hibernate/orm/3.3/reference/en/html/queryhql.html#queryhql-subqueries
Supposing I have entity Lecturer and Course two entities having many to many relationships in JPA 2.0
It is perfectly OK to have a non-annotated entity LecturerCourse (with multi-table selection columns, not annotated) and JPQL like this working.
final Query query = em.createQuery(
"select new com.cs.entity.LectureCourse(l.id, l.name, l.surName, " +
"l.type, c.code, c.name) from lecturer l join l.courses c where l.id = :l_id"
);
How can I do the same with JPA Criteria API?
Here are the code for Lecturer and Courses respectively
#Entity(name = "course")
public class Course implements Serializable {
#Id
#Column(name = "course_code", columnDefinition = "char(6)",
unique = true, nullable = false)
private String code;
#Column(name = "course_name")
private String name;
#ManyToMany(mappedBy = "courseSet", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
private Set<Student> students;
#ManyToOne(fetch = FetchType.EAGER, targetEntity = Lecturer.class)
#JoinColumn(name = "lecture_id")
private Lecturer lecturer;
public Course() {
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set<Student> getStudents() {
return students;
}
public void setStudents(Set<Student> students) {
this.students = students;
}
public Lecturer getLecturer() {
return lecturer;
}
public void setLecturer(Lecturer lecturer) {
this.lecturer = lecturer;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof Course)) return false;
Course course = (Course) o;
if (code != null ? !code.equals(course.code) : course.code != null) return false;
if (name != null ? !name.equals(course.name) : course.name != null) return false;
if (students != null ? !students.equals(course.students) : course.students != null) return false;
return true;
}
#Override
public int hashCode() {
int result = code != null ? code.hashCode() : 0;
result = 31 * result + (name != null ? name.hashCode() : 0);
result = 31 * result + (students != null ? students.hashCode() : 0);
return result;
}
}
#Entity(name = "lecturer")
public class Lecturer {
public static enum LectureType{
FULL_TIME, PART_TIME
}
#Id
#Column(name = "lecture_id", nullable = false,
unique = true, columnDefinition = "char(8)")
private String id;
#Column(name = "lecture_name", length = 20, nullable = false)
private String name;
#Column(name = "lecture_sur_name", length = 20, nullable = false)
private String surName;
#Enumerated(EnumType.ORDINAL)
#Column(name = "lecture_type", columnDefinition = "char(1)")
private LectureType type;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "lecturer", fetch = FetchType.EAGER)
private Set<Course> courses;
public Lecturer() {
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getSurName() {
return surName;
}
public void setSurName(String surName) {
this.surName = surName;
}
public LectureType getType() {
return type;
}
public void setType(LectureType type) {
this.type = type;
}
public Set<Course> getCourses() {
return courses;
}
public void setCourses(Set<Course> courses) {
this.courses = courses;
for(final Course course : this.courses){
course.setLecturer(this);
}
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof Lecturer)) return false;
Lecturer lecturer = (Lecturer) o;
if (id != null ? !id.equals(lecturer.id) : lecturer.id != null) return false;
if (name != null ? !name.equals(lecturer.name) : lecturer.name != null) return false;
if (surName != null ? !surName.equals(lecturer.surName) : lecturer.surName != null) return false;
if (type != lecturer.type) return false;
return true;
}
#Override
public int hashCode() {
int result = id != null ? id.hashCode() : 0;
result = 31 * result + (name != null ? name.hashCode() : 0);
result = 31 * result + (surName != null ? surName.hashCode() : 0);
result = 31 * result + (type != null ? type.hashCode() : 0);
return result;
}
}
What you're looking for is a form of CriteriaQuery#multiselect ... I'm assuming you're generating an appropriate static metamodel (that's where the EntityClass_.field pieces come from) but working by hand I come up with something like:
CriteriaBuilder builder = em.getCriteriaBuilder();
CriteriaQuery<LectureCourse> criteria = builder.createQuery(LectureCourse.class);
Root<Lecturer> l = criteria.from(Lecturer.class);
Path<Course> c = l.join(Lecturer_.courses);
ParameterExpression<String> l_id = builder.parameter(String.class);
Predicate lecturerIdMatches = builder.equal(l.get(Lecturer_.id),l_id);
TypedQuery<LectureCourse> query = em.createQuery(criteria.multiselect(l.get(Lecturer_.id), l.get(Lecturer_.name), l.get(Lecturer_.surName), l.get(Lecturer_.type), c.get(Course_.code), c.get(Course_.name)).where(lecturerIdMatches));
query.setParameter(l_id,"queryvalue");
List<LectureCourse> results = query.getResultList();