“ManyToMany”关系问题Spring JPA

我是Spring的新手，所以很遗憾，如果事实证明这是一个非常愚蠢的问题，但我已经尝试了几乎所有的东西。我有用户和角色实体，他们之间有很多关系。如果我删除关系它工作得很好，否则我会得到错误。你能帮我吗？“ManyToMany”关系问题Spring JPA

中的作用类

import javax.persistence.*; 
import java.util.HashSet; 
import java.util.Set; 


@Entity 
public class Role { 

    private Long id; 
    private Set<User> users = new HashSet<>(); 

    public Role(){} 
    @Id 
    @GeneratedValue(strategy = GenerationType.AUTO) 
    @Column(name = "id") 
    public Long getId() { 
     return id; 
    } 

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


    @ManyToMany(mappedBy = "roles") 
    public Set<User> getUsers() { 
     return users; 
    } 

    public void setUsers(Set<User> users) { 
     this.users = users; 
    } 
}

User类

import javax.persistence.*; 
import java.util.HashSet; 
import java.util.Set; 


@Entity 
public class User { 


    private Long id; 
    private Set<Role> roles = new HashSet<>(); 

    public User(){} 

    @Id 
    @GeneratedValue(strategy = GenerationType.AUTO) 
    @Column(name = "id") 
    public Long getId() { 
     return id; 
    } 

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


    @ManyToMany 
    @JoinTable(name = "user_roles", joinColumns = @JoinColumn(name = "user_id",referencedColumnName = "id"), 
      inverseJoinColumns = @JoinColumn(name = "role_id",referencedColumnName = "id")) 
    public Set<Role> getRoles() { 
     return roles; 
    } 

    public void setRoles(Set<Role> roles) { 
     this.roles = roles; 
    } 
}

的失误

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1628) ~[spring-beans-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1081) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:856) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) ~[spring-context-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] 
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:737) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] 
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:370) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] 
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] 
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] 
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] 
    at com.restaurant.AppConfig.main(AppConfig.java:14) [main/:na] 
Caused by: javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory 
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.persistenceException(EntityManagerFactoryBuilderImpl.java:954) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:882) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final] 
    at org.springframework.orm.jpa.vendor.SpringHibernateJpaPersistenceProvider.createContainerEntityManagerFactory(SpringHibernateJpaPersistenceProvider.java:60) ~[spring-orm-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:353) ~[spring-orm-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:370) ~[spring-orm-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:359) ~[spring-orm-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1687) ~[spring-beans-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1624) ~[spring-beans-4.3.7.RELEASE.jar:4.3.7.RELEASE] 
    ... 16 common frames omitted 
Caused by: org.hibernate.tool.schema.spi.SchemaManagementException: Unable to execute schema management to JDBC target [alter table user_roles add constraint FKrhfovtciq1l558cw6udg0h0d3 foreign key (role_id) references role (id)] 
    at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:59) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlString(SchemaMigratorImpl.java:431) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applySqlStrings(SchemaMigratorImpl.java:420) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.applyForeignKeys(SchemaMigratorImpl.java:386) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigrationToTargets(SchemaMigratorImpl.java:214) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.tool.schema.internal.SchemaMigratorImpl.doMigration(SchemaMigratorImpl.java:60) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:134) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.tool.hbm2ddl.SchemaUpdate.execute(SchemaUpdate.java:101) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:472) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:444) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:879) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final] 
    ... 22 common frames omitted 
Caused by: java.sql.SQLException: Cannot add foreign key constraint 
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964) ~[mysql-connector-java-5.1.41.jar:5.1.41] 
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973) ~[mysql-connector-java-5.1.41.jar:5.1.41] 
    at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909) ~[mysql-connector-java-5.1.41.jar:5.1.41] 
    at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2527) ~[mysql-connector-java-5.1.41.jar:5.1.41] 
    at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680) ~[mysql-connector-java-5.1.41.jar:5.1.41] 
    at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2497) ~[mysql-connector-java-5.1.41.jar:5.1.41] 
    at com.mysql.jdbc.StatementImpl.executeUpdateInternal(StatementImpl.java:1540) ~[mysql-connector-java-5.1.41.jar:5.1.41] 
    at com.mysql.jdbc.StatementImpl.executeLargeUpdate(StatementImpl.java:2595) ~[mysql-connector-java-5.1.41.jar:5.1.41] 
    at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1468) ~[mysql-connector-java-5.1.41.jar:5.1.41] 
    at org.hibernate.tool.schema.internal.TargetDatabaseImpl.accept(TargetDatabaseImpl.java:56) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final] 
    ... 32 common frames omitted 

:bootRun FAILED

来源

2017-07-08 Jack Wayne

嗨，你手动设置数据库，或者让Hibernate的为你做这个？如果你只是测试你可以让HIbernate下降并创建你的模式，看看[这里]（https://stackoverflow.com/questions/40561314/springboot-jpa-cant-create-table） –

我正在使用spring。 jpa.hibernate.ddl-auto = update，Hibernate自己创建表。它在第一次创建和更新时工作正常。但是让我困惑的是为什么更新是在创建表格。（顺便一提，非常感谢！） –

JPA提供程序服从您使用它的属性。您尚未发布您的JPA配置... –

考虑使得这种单向的。在正常情况下，您只需要知道给定用户具有哪些角色。所以，最好的解决方法是彻底删除角色类中的getUsers（）。

为了让它运行起来，请在关系的两侧使用连接表。试试这个; Role.java;

@ManyToMany 
@JoinTable(name = "user_roles", 
    joinColumns = @JoinColumn(name="role_id"), 
    inverseJoinColumns = @JoinColumn(name="user_id")) 
public Set<User> getUsers()

User.java

@ManyToMany 
@JoinTable(name="user_roles", 
    [email protected](name="user_id"), 
    [email protected](name="role_id")) 
public Set<Role> getRoles() {

[编辑]尝试添加这application.properties，但仅用于测试！

spring.jpa.hibernate.ddl-auto=create-drop

以防万一，从MySQL我也尝试

drop database your-database-name; 
create database your-database-name;

来源

2017-07-08 13:00:05 GrumpyWelshGit

在这两种情况下，我都会遇到同样的错误。这一行可能是我的主要问题“由：java.sql.SQLException：无法添加外键约束”引起的？ –

我同意，但不清楚为什么它失败。快速问题，你是否在测试之间放置你的表格？从早期的尝试中可能会有一些想法。你是否使用默认配置的Spring启动？ – GrumpyWelshGit

是的，我正在使用默认配置。我不放弃表格，但在某些时候我放弃了所有的表格（我认为它可以解决我的问题）并再次运行。它没有锻炼，表格是在数据库中创建的，但是和以前一样有错误。 –

“ManyToMany”关系问题Spring JPA

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