Question

我正在使用Spring数据JPA，并正在建立我的第一个ManyToMany关系。我将第一个对象“用户”定义为：

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

@Entity
@Table(name = "SMX0_PAR_USER", schema = "SMX0_INPUT_DAY")
public class User {

    @Id
    private String userID;
    private String username;


    @ManyToMany
    @JoinTable(
        name = "SMX0_PAR_USER_ROLE",
        schema = "SMX0_INPUT_DAY",
        joinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "userID"),
        inverseJoinColumns = @JoinColumn(name = "ROLE_ID", referencedColumnName = "roleID")
    )
    private Set<Role> roleSet;


    protected User(){

    }

    public User(String userID, String username){
        this.userID = userID;
        this.username = username;
    }

第二个对象“角色”定义为：

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.ManyToMany;
import javax.persistence.Table;
import java.util.Set;

@Entity
@Table(name = "SMX0_PAR_ROLE", schema = "SMX0_INPUT_DAY")
public class Role {

    @Id
    private int roleID;
    private String rolename;

    @ManyToMany(mappedBy = "roleSet")
    private Set<User> userSet;


    protected Role(){

    }

    public Role(int roleID, String role){
        this.roleID = roleID;
        this.rolename = role;
    }

两个类中的所有字段都有吸气剂和吸气剂。
获取与角色没有多对多关系的用户是完美的。

尝试访问其中包含以下百里香代码的页面时：

 <tr th:each="user : ${users}">
     <td th:text="${user.getUserID()}">user ID</td>
     <td th:text="${user.getUsername()}">username</td>
     <td><span th:each="role : ${user.getRoleSet()}">
         <span th:text="${role.getRolename()}">rolename</span>
     </span></td>
</tr>

我得到例外：

org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates//module/userManagement/index.html]")
…
Caused by: org.attoparser.ParseException: could not extract ResultSet
…
Caused by: org.hibernate.exception.SQLGrammarException: could not extract ResultSet
…
Caused by: java.sql.SQLSyntaxErrorException: ORA-00904: "ROLESET0_"."ROLE_ID": invalid identifier

这是怎么回事，当我将联接表名称显式设置为其他名称时，为什么会引用诸如“ ROLESET0_”之类的名称？我该如何强制使用已经给出的表名？

Answer 1

ROLESET0_是hibernate在其生成的查询中分配的别名。如果您设置spring.jpa.show-sql=true以查看休眠产生的完整查询，可能会有所帮助。您还可以设置spring.jpa.properties.hibernate.format_sql=true使其更具可读性。

Answer 2

尝试为两个类中的所有字段添加注释@Column (name = "YourColumnName")。

referencedColumnName参数也应该是此外键列引用的列的名称。

    public class User {
       @Id
       @Column(name = "YourColumnName")
       private int roleID;
       @Column(name = "YourColumnName")
       private String rolename;

       @ManyToMany
        @JoinTable(
        name = "SMX0_PAR_USER_ROLE",
        schema = "SMX0_INPUT_DAY",
        joinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "YourColumnName"),
        inverseJoinColumns = @JoinColumn(name = "ROLE_ID", referencedColumnName ="YourColumnName"))
        .....

        }

   public class Role {

       @Id
       @Column(name = "YourColumnName")
       private int roleID;
       @Column(name = "YourColumnName")
       private String rolename;
       .......

       }

如何强制将给定的表名用于可联接项？

2 个答案: