Hibernate ManyToMany Bidirectional mapping throw DDL Exception

Question

I have 4 Entities. User , Role , EmployeeRole and AccessPermission . 4 Entities connect each other by foreign key. I encountered a problem while bidirectional ManyToMany relationship with User and EmployeeRole. User table owner of relational mapping. I need also access User information from EmployeeRole table. So I made bidirectional OneToMany relationship in both entities.

I am getting DDL exception while running the codes. Please help me out from this problem. I tried so many search in Google.

The User Entity:

@Entity
@Table(name="user")
public class User{

@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "idgenerator")
@SequenceGenerator(initialValue = 1, name = "idgenerator", sequenceName = "usersSeq")
private long id;

@Column(name="company_id")
private String companyId;

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

@Column(name= "firstname")
private String firstName;

@Column(name = "lastname")
private String lastName;

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

@Column(name = "active")
private int active;

@ManyToMany(cascade = CascadeType.PERSIST)
@JoinTable(name = "user_role", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "role_id"))
private Set<Role> roles;

@ManyToMany(cascade = CascadeType.PERSIST)
@JoinTable(name = "user_has_role", joinColumns = @JoinColumn(name = "user_id"), inverseJoinColumns = @JoinColumn(name = "emp_role_id"))
private Set<EmployeeRole> empRoles = new HashSet<>();
// geters and setters. 
}

EmployeeRole Entity:

@Entity
@Table(name="employeeRole")
public class EmployeeRole extends AbstractData {

@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "idgenerator")
@SequenceGenerator(initialValue = 1, name = "idgenerator", sequenceName = "employeeRoleSeq")
@Column(name = "id", updatable = false, nullable = false)
private long id;

@NotBlank
@Size(min = 1, max = 255)
@Column(name="roleName")
protected String roleName;

@Column(name="roleDescription")
protected String roleDescription;

@ManyToMany(mappedBy="empRoles")  
private Set<User> user = new HashSet<>();
// geters and setters. 
}

The error messages:

alter table user_has_role 
   add constraint FKdtkvc2iy3ph1rkvd67yl2t13m 
   foreign key (user_id) 
   references user (id)

2019-07-19 14:05:38.758  WARN 11756 --- [           main] o.h.t.s.i.ExceptionHandlerLoggedImpl     : GenerationTarget encountered exception accepting command : Error executing DDL "
    alter table user_has_role 
       add constraint FKdtkvc2iy3ph1rkvd67yl2t13m 
       foreign key (user_id) 
       references user (id)" via JDBC Statement

org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL "
    alter table user_has_role 
       add constraint FKdtkvc2iy3ph1rkvd67yl2t13m 
       foreign key (user_id) 
       references user (id)" via JDBC Statement
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:67) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.applySqlString(AbstractSchemaMigrator.java:559) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.applySqlStrings(AbstractSchemaMigrator.java:504) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.applyForeignKeys(AbstractSchemaMigrator.java:433) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.performMigration(AbstractSchemaMigrator.java:249) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.doMigration(AbstractSchemaMigrator.java:114) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.performDatabaseAction(SchemaManagementToolCoordinator.java:183) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.tool.schema.spi.SchemaManagementToolCoordinator.process(SchemaManagementToolCoordinator.java:72) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:310) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:467) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:939) [hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:57) [spring-orm-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:365) [spring-orm-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:390) [spring-orm-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:377) [spring-orm-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.afterPropertiesSet(LocalContainerEntityManagerFactoryBean.java:341) [spring-orm-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1821) [spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1758) [spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:593) [spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) [spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) [spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) [spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) [spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1105) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.5.RELEASE.jar:5.1.5.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) ~[spring-boot-2.1.3.RELEASE.jar:2.1.3.RELEASE]
    at com.tigerslab.tigererp.TigerErpApplication.main(TigerErpApplication.java:10) ~[classes/:na]
Caused by: java.sql.SQLException: Can't create table `possystem`.`#sql-4a0_17c` (errno: 150 "Foreign key constraint is incorrectly formed")
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129) ~[mysql-connector-java-8.0.15.jar:8.0.15]
    at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97) ~[mysql-connector-java-8.0.15.jar:8.0.15]
    at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122) ~[mysql-connector-java-8.0.15.jar:8.0.15]
    at com.mysql.cj.jdbc.StatementImpl.executeInternal(StatementImpl.java:782) ~[mysql-connector-java-8.0.15.jar:8.0.15]
    at com.mysql.cj.jdbc.StatementImpl.execute(StatementImpl.java:666) ~[mysql-connector-java-8.0.15.jar:8.0.15]
    at com.zaxxer.hikari.pool.ProxyStatement.execute(ProxyStatement.java:95) ~[HikariCP-3.2.0.jar:na]
    at com.zaxxer.hikari.pool.HikariProxyStatement.execute(HikariProxyStatement.java) ~[HikariCP-3.2.0.jar:na]
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:54) ~[hibernate-core-5.3.7.Final.jar:5.3.7.Final]
    ... 33 common frames omitted

Answer 1

Usually, this kind of error happens when you are trying to reference table by the key and their length or data type is different. As of what I see, there are two suggestions I can give you.

First, make sure to specify @JoinTable with @JoinColumn(name = "id", referencedColumnName = "user_id") annotation for EmployeeRole class from the right side. Update your mapping like that (make sure to remove it from User entity though):

@ManyToMany(mappedBy="empRoles")
@JoinTable(name = "user_has_role", joinColumns = @JoinColumn(name = "emp_role_id"), inverseJoinColumns = @JoinColumn(name = "user_id"))
private Set<User> user = new HashSet<>();

Second, make sure you use wrappers for your ids, because newly created entities will have ids of 0 (primitives cannot be null), while you want null (due to the fact that id will be generated upon insertion).

@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "idgenerator")
@SequenceGenerator(initialValue = 1, name = "idgenerator", sequenceName = "usersSeq")
private Long id;