many-to-many - 如何使用 Ebean 处理单向多对多关系

Question

我对 Ebean 有疑问。我有常用的对象 PsecUser、PsecRoles 和 PsecPermission。一个用户可以有很多权限或角色，一个角色可以有很多权限。这里的代码(摘录):

@Entity
public class PsecPermission {

    @Id
    @GeneratedValue
    private Long id;

    @Column(unique=true, nullable=false)
    private String name;

    @Column(nullable=false)
    private String type = PsecBasicPermission.class.getName();

    @Column(nullable=false)
    private String target;

    @Column(nullable=false)
    private String actions;

}


@Entity
public class PsecRole  {

    @Id
    @GeneratedValue
    private Long id;

    @Column(unique=true, nullable=false)
    private  String name;

    @Temporal(TemporalType.TIMESTAMP)
    private Date lastUpdate;

    @ManyToMany(fetch=FetchType.EAGER)
    private List<PsecPermission> psecPermissions;

    private boolean defaultRole = false;

}

我编写了以下辅助方法:

public PsecRole createOrUpdateRole(String name, boolean defaultRole, String... permissions) {
        PsecRole result = server.find(PsecRole.class).
                where().eq("name", name).findUnique();
        if (result == null) {
            result = new PsecRole();
            result.setName(name);
        }
        final List<PsecPermission> permissionObjects = server.find(PsecPermission.class).
                where().in("name", (Object[])permissions).findList();
        result.setPsecPermissions(permissionObjects);
        result.setDefaultRole(defaultRole);
        final Set <ConstraintViolation <PsecRole>> errors = 
                Validation.getValidator().validate(result);
        if (errors.isEmpty()) {
            server.save(result);
            server.saveManyToManyAssociations(result, "psecPermissions");
        } else {
            log.error("Can't save role: " + name +"!");
            for (ConstraintViolation <PsecRole> constraintViolation : errors) {
                log.error("   " + constraintViolation);
            }
        }
        return result;
}

并尝试以下测试:

@Test
public void testCreateOrUpdateRole() {
    String[] permNames = {"Test1", "Test2", "Test3"};
    List <PsecPermission> permissions = new ArrayList <PsecPermission>();
    for (int i = 0; i < permNames.length; i++) {
        helper.createOrUpdatePermission(permNames[i], "target"+ i, "actions" +i);
        PsecPermission perm = server.find(PsecPermission.class).where().eq("name", permNames[i]).findUnique();
        assertThat(perm.getTarget()).isEqualTo("target" + i);
        assertThat(perm.getActions()).isEqualTo("actions" + i);
        permissions.add(perm);
    }

    PsecRole orgRole = helper.createOrUpdateRole(ROLE, false, permNames);
    testRole(permNames, orgRole);
    PsecRole role = server.find(PsecRole.class).where().eq("name", ROLE).findUnique();
    testRole(permNames, role);

}
private void testRole(String[] permNames, PsecRole role) {
    assertThat(role).isNotNull();
    assertThat(role.getName()).isEqualTo(ROLE);
    assertThat(role.isDefaultRole()).isEqualTo(false);
    assertThat(role.getPermissions()).hasSize(permNames.length);
}

如果它检查读取角色的权限数量，则失败。它始终为 0。我查看了数据库，发现 psec_role_psec_permission 始终为空。

知道代码有什么问题吗？

您可以从 https://github.com/opensource21/ebean-samples/downloads 获得一个纯 Ebean 示例它使用来自 ebean 的 eclipse-plugin。

Answer 1

这个问题有两种解决方案:

只需在 PsceRole 添加级联选项

@ManyToMany(fetch=FetchType.EAGER, cascade=CascadeType.ALL)
private List<PsecPermission> psecPermissions;

并删除 server.saveManyToManyAssociations(result, "psecPermissions"); 你会在 cascade-solution-branch 中找到它.

更简洁的解决方案，因为您不需要定义 cascase——也许您不想要它:只是不要替换列表，只需将您的条目添加到列表中即可。更好的是添加新的并删除旧的。这意味着在 createOrUpdateRole 中:

result.getPsecPermissions().addAll(permissionObjects);

代替

result.setPsecPermissions(permissionObjects);