Can you link two entitys with OneToOne relationship without a foreign key?

Question

Hello i am having problems with assigning OneToOne relationships in my project. This is my Player.java

@Table(name = "player")
public class Player implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "player_id", unique = true, nullable = false)
    private Integer id;

    @NotNull
    private String username, password, email;
    @NotNull
    private Integer rank;
    private Integer userType; // 0 - regular user, 1 - admin

    private Review review;
    public Player() {}

    public Player(@NotNull String username, @NotNull String password, @NotNull String email, @NotNull Integer rank, Integer userType) {
        this.username = username;
        this.password = password;
        this.email = email;
        this.rank = rank;
        this.userType = userType;
    }

    // Getters and Setters
    @JsonGetter("id")
    public Integer getId() { return id; }
    public void setId(Integer id) { this.id = id; }

    @JsonGetter("username")
    public String getUsername() { return username; }
    public void setUsername(String username) { this.username = username; }

    @JsonGetter("password")
    public String getPassword() { return password; }
    public void setPassword(String password) { this.password = password; }

    @JsonGetter("email")
    public String getEmail() { return email; }
    public void setEmail(String email) { this.email = email; }

    @JsonGetter("rank")
    public Integer getRank() { return rank; }
    public void setRank(Integer rank) { this.rank = rank; }

    @JsonGetter("user_type")
    public Integer getUserType() { return userType; }
    public void setUserType(Integer userType) { this.userType = userType; }

    public Review getReview() {
        return review;
    }

    public void setReview(Review review) {
        this.review = review;
    }
}

Review.java

@Entity
@Table(name = "review")
public class Review {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "review_id", insertable = false, updatable = false, unique = true, nullable = false)
    private int id;

    @Column(name = "timestamp")
    private Timestamp timestamp;

    @Column(name = "description")
    private String description;

    private Player player;


    // Constructors
    public Review() {
    }

    public Review(int Id, Timestamp timestamp, String description) {
        this.id = Id;
        this.timestamp = timestamp;
        this.description = description;
    }

    // Getters and Setters
    @JsonGetter("id")
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    @JsonGetter("timestamp")
    public Timestamp getTimestamp() {
        return timestamp;
    }

    public void setTimestamp(Timestamp timestamp) {
        this.timestamp = timestamp;
    }

    @JsonGetter("description")
    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    @JsonGetter("player")
    public Player getPlayer() {
        return player;
    }

    public void setPlayer(Player player) {
        this.player = player;
    }
}

player.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.montini.teamsports.model">
    <class name="Player" table="player">

        <meta attribute="class-description">
            This class contains the player detail.
        </meta>

        <id name="id" type="int" column="player_id">
            <generator class="native"/>
        </id>

        <property name="username" column="username" type="string"/>
        <property name="password" column="password" type="string"/>
        <property name="email" column="email" type="string"/>
        <property name="rank" column="user_rank" type="int"/>
        <property name="userType" column="user_type" type="int"/>

        <one-to-one name="review"  class="com.montini.teamsports.model.Review"
                    constrained="true"></one-to-one>

        <!--<property name="userType">-->
        <!--    <type name="org.hibernate.type.EnumType">-->
        <!--        <param name="enumClass">com.montini.teamsports.model.UserType</param>-->
        <!--        <param name="useNamed">true</param>-->
        <!--    </type>-->
        <!--</property>-->

    </class>
</hibernate-mapping>

review.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">

<hibernate-mapping package="com.montini.teamsports.model">
    <class name="Review" table="review">
        <id name="id" column="review_id">
        </id>

        <one-to-one name="player" foreign-key="player_id" class="com.montini.teamsports.model.Player" cascade="save-update">
        </one-to-one>
        <property name="timestamp" column="timestamp" type="timestamp"/>
        <property name="description" column="description" type="string"/>



    </class>
</hibernate-mapping>

This is DDL

CREATE TABLE player
(
    player_id       int primary key not null auto_increment,
    username        varchar(30),
    password        varchar(30),
    email           varchar(50),
    user_rank       int,
    user_type       int,
    unique (player_id)
);

CREATE TABLE review
(
    review_id   int PRIMARY KEY NOT NULL AUTO_INCREMENT,
    player_id int not null,
    timestamp   datetime,
    description text,
    unique (review_id),
    KEY FK_player_review (player_id),
  CONSTRAINT FK_player_review FOREIGN KEY (player_id) REFERENCES player (player_id)
);

the test class is:

public class ReviewTest {

    public static final Logger log = LoggerFactory.getLogger(Review.class);

    @Test
    public void test1() {

        Session session = null;
        Transaction transaction = null;

        try {
            session = HibernateUtil.getSessionFactory().openSession();
            transaction = session.beginTransaction();


            Player player = new Player();
            player.setUsername("Ignas");
            player.setPassword("kokokok");
            player.setEmail("jojo@jojo.com");
            player.setUserType(0);
            player.setRank(10);



            Review review = new Review();
            review.setTimestamp(new Timestamp(System.currentTimeMillis()));
            review.setDescription("New message from team-sport user.");
            review.setPlayer(player);
            player.setReview(review);

            session.save(player);
            session.save(review);

            transaction.commit();


        } catch (RuntimeException e) {

            e.printStackTrace();
        } finally {
            if (session != null) {
                session.close();
            }
        }
    }
}

The error i am getting is this:

javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: could not execute statement
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:154)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181)
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188)
    at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1348)
    at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:435)
    at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3221)
    at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2389)
    at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:447)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:183)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$300(JdbcResourceLocalTransactionCoordinatorImpl.java:40)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:281)
    at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:101)
    at com.montini.teamsports.ReviewTest.test1(ReviewTest.java:47)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.platform.commons.util.ReflectionUtils.invokeMethod(ReflectionUtils.java:436)
    at org.junit.jupiter.engine.execution.ExecutableInvoker.invoke(ExecutableInvoker.java:115)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.lambda$invokeTestMethod$6(TestMethodTestDescriptor.java:170)
    at org.junit.jupiter.engine.execution.ThrowableCollector.execute(ThrowableCollector.java:40)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.invokeTestMethod(TestMethodTestDescriptor.java:166)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:113)
    at org.junit.jupiter.engine.descriptor.TestMethodTestDescriptor.execute(TestMethodTestDescriptor.java:58)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$3(HierarchicalTestExecutor.java:112)
    at org.junit.platform.engine.support.hierarchical.SingleTestExecutor.executeSafely(SingleTestExecutor.java:66)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.executeRecursively(HierarchicalTestExecutor.java:108)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.execute(HierarchicalTestExecutor.java:79)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$2(HierarchicalTestExecutor.java:120)
    at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
    at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
    at java.util.Iterator.forEachRemaining(Iterator.java:116)
    at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
    at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
    at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$3(HierarchicalTestExecutor.java:120)
    at org.junit.platform.engine.support.hierarchical.SingleTestExecutor.executeSafely(SingleTestExecutor.java:66)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.executeRecursively(HierarchicalTestExecutor.java:108)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.execute(HierarchicalTestExecutor.java:79)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$2(HierarchicalTestExecutor.java:120)
    at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
    at java.util.stream.ReferencePipeline$2$1.accept(ReferencePipeline.java:175)
    at java.util.Iterator.forEachRemaining(Iterator.java:116)
    at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
    at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
    at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
    at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
    at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
    at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
    at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.lambda$executeRecursively$3(HierarchicalTestExecutor.java:120)
    at org.junit.platform.engine.support.hierarchical.SingleTestExecutor.executeSafely(SingleTestExecutor.java:66)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.executeRecursively(HierarchicalTestExecutor.java:108)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor$NodeExecutor.execute(HierarchicalTestExecutor.java:79)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutor.execute(HierarchicalTestExecutor.java:55)
    at org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine.execute(HierarchicalTestEngine.java:43)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:170)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:154)
    at org.junit.platform.launcher.core.DefaultLauncher.execute(DefaultLauncher.java:90)
    at com.intellij.junit5.JUnit5IdeaTestRunner.startRunnerWithArgs(JUnit5IdeaTestRunner.java:69)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
Caused by: org.hibernate.exception.GenericJDBCException: could not execute statement
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:113)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:99)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:200)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3208)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:3722)
    at org.hibernate.action.internal.EntityInsertAction.execute(EntityInsertAction.java:91)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:604)
    at org.hibernate.engine.spi.ActionQueue.lambda$executeActions$1(ActionQueue.java:478)
    at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:475)
    at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:349)
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:40)
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:108)
    at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1344)
    ... 63 more
Caused by: java.sql.SQLException: Field 'player_id' doesn't have a default value
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:121)
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:89)
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:116)
    at com.mysql.cj.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1867)
    at com.mysql.cj.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:2029)
    at com.mysql.cj.jdbc.PreparedStatement.executeUpdateInternal(PreparedStatement.java:1970)
    at com.mysql.cj.jdbc.PreparedStatement.executeLargeUpdate(PreparedStatement.java:4996)
    at com.mysql.cj.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:1955)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:197)
    ... 74 more

I think the main problem is that is tells that player_id has no default value. but when debugging this test it shows that player is assigned to review.

Answer 1

Seems like, you are not passing player to review while persisting. you will have to persist player first and than before persisting the review you have fetch player for which you would like to add review and set it manually in your business logic.