Hibernate 持久化 ArrayList - 问题 [英] Hibernate persisting ArrayList - Issues

问题描述

在使用此功能时遇到一些麻烦.我正在创建一个带有锦标赛的网站，用户可以注册.比赛将有一个注册会员名单.它不保存 User 对象，只保存用户电子邮件地址，无论如何它都是用户表的键.我想以这样一种方式存储数组列表，即我将拥有锦标赛 ID 的多个副本，但每个锦标赛 ID 只有一个用户名实例.

Having some trouble getting this working. I am creating a site with a Tournament, which users can register for. The Tournament will have a list of registered members. It's not holding User objects, just the user email address, which is the a key for the user table anyway. I want to store the array list in such a way that I will have multiple copies of the tournament id, but only one instance of a username per tournament id.

例如T_ID 用户名1 汤姆1 迈克1 约翰2 汤姆2 克里斯2 提米3 提米3克里斯

eg T_ID Username 1 Tom 1 Mike 1 John 2 Tom 2 Chris 2 Timmy 3 Timmy 3 Chris

等

这是表的 SQL.

DROP TABLE IF EXISTS `mtc`.`tournament` ;

CREATE TABLE IF NOT EXISTS `mtc`.`tournament` (
  `id` INT NOT NULL,
  `tournamentName` VARCHAR(100) NULL,
  `tournamentGender` VARCHAR(45) NULL,
  `tournamentType` VARCHAR(45) NULL,
  `tournamentCategory` VARCHAR(45) NULL,
  `tournamentStyle` VARCHAR(45) NULL,
  PRIMARY KEY (`id`))
ENGINE = InnoDB;


-- -----------------------------------------------------
-- Table `mtc`.`tournament_eligible`
-- -----------------------------------------------------
DROP TABLE IF EXISTS `mtc`.`tournament_eligible` ;

CREATE TABLE IF NOT EXISTS `mtc`.`tournament_eligible` (
  `id` INT NOT NULL,
  `username` VARCHAR(45) NULL,
  PRIMARY KEY (`id`),
  CONSTRAINT `fk_tournament_eligible_tournament1`
    FOREIGN KEY (`id`)
    REFERENCES `mtc`.`tournament` (`id`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB;

我有两个这样的课程.

锦标赛.java

    @Entity
    @Table(name = "tournament")
    public class Tournament implements Event {

        @Id
        @GeneratedValue
        private int id;

        @OneToMany
        @JoinColumn(name = "id")
        private List<User> eligible; // Contains a list of eligible members

        @Size(min = 5, max = 45, message = "Tournament Name must be between 5 and 60 characters", groups = {
                PersistenceValidationGroup.class, FormValidationGroup.class })
        private String tournamentName; // Specified the name of the tournament

        private String tournamentGender = "MIXED"; // Specifies where a tournament
                                                    // is M(ale), F(emale) or MIXED;

        private String tournamentType = "S"; // Specifies S(ingles) or D(oubles)

        private String tournamentCategory = "O"; // Specifies Member_Type to be
                                                    // S(enior) only, J(unior) only,
                                                    // or O(pen) Tournament

        private String tournamentStyle = "L"; // Specfies type of Tournament to be
                                                // (L)adder/(L)eague, (B)ucket or
                                                // (G)roup - Probably change this to
                                                // a class later on.

        public Tournament() {
            this.eligible = new ArrayList<User>();
        }

// getters and setters

注册类

    @Entity
    @Table(name="tournament_eligible")
    public class Registered {


        @Id
        @Column(name="id")
        private int tournamentID;

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

        @OneToMany(mappedBy="tournament")
        private List<String> registered;

// getter and setters

我使用的是正确的 javax.* 注释，而不是 Hibernate 注释.

I am using the proper javax.* annotations, not the Hibernate ones.

当前错误:由:org.hibernate.AnnotationException:@OneToOne 或 @ManyToOne on events.tournaments.Tournament.eligible 引用未知实体:java.util.List

Current Error: Caused by: org.hibernate.AnnotationException: @OneToOne or @ManyToOne on events.tournaments.Tournament.eligible references an unknown entity: java.util.List

我确实设置了 Hibernate 配置以查看包含注册实体的包.

I do have the Hibernate config set up to look in the package with the Register entity.

<beans profile="production">
        <jee:jndi-lookup jndi-name="jdbc/mtc" id="dataSource"
            expected-type="javax.sql.DataSource">
        </jee:jndi-lookup>
        <bean id="transactionManager"
            class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
            <property name="dataSource" ref="dataSource"></property>
        </bean>
        <tx:annotation-driven />
        <bean id="sessionFactory"
            class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
            <property name="dataSource" ref="dataSource"></property>
            <property name="hibernateProperties">
                <props>
                    <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
                </props>
            </property>
            <property name="packagesToScan">
                <list>
                    <value>users</value>
                    <value>dao</value>
                    <value>events.tournaments</value>
                </list>
            </property>
        </bean>
        <bean id="exceptionTranslator"
            class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor">
        </bean>
    </beans>

推荐答案

在您的 Register 类中，您试图将字符串列表映射为实体:

In your Register class, you are trying to map a list of strings as if they were entities:

    @OneToMany(mappedBy="tournament")
    private List<String> registered;

@OneToMany 仅用于实体之间的关系.List 和 String 都不是实体.如果要将基本值(如 String)的 Collection 映射到表，请查看 @CollectionTable 注释.

@OneToMany is for relationships between entities only. Neither List nor String are entities. If you want to map a Collection of basic values (like String) to a table, take a look at the @CollectionTable annotation.

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