不要放纵你的爱情，不要让欲望的利剑把你射中——莎士比亚

前两天写了mybatis一对多查询

今天写一下在代码中如何使用@One实现一对一的关联查询

这里的@One注解类名org.apache.ibatis.annotations.One

代码如下：

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@Select("<script>" +
        "select *" +
        "        from user_role\n" +
        "        <where>" +
        "            <if test=\"userId != null\">" +
        "                AND user_id = #{userId}" +
        "            </if>" +
        "            <if test=\"roleId != null\">" +
        "                AND role_id = #{roleId}" +
        "            </if>" +
        "        </where>" +
        "</script>")
@Results({
        @Result(property = "id", column = "id"),
        @Result(property = "userId", column = "user_id"),
        @Result(property = "roleId", column = "role_id"),
        @Result(property = "role", javaType = RoleInfo.class, column = "role_id",
                one = @One(select = "com.ruben.mapper.RoleMapper.getById"))
})
List<UserRole> selectList(UserRole userRole);

然后执行单元测试：

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@Test
void testOne(@Autowired UserRoleMapper userRoleMapper) {
    List<UserRole> userRoles = userRoleMapper.selectList(new UserRole() {{
        setUserId(1L);
    }});
    Assertions.assertEquals("admin", userRoles.get(0).getRole().getRoleName());
    Assertions.assertEquals("user", userRoles.get(1).getRole().getRoleName());
}

结果：

image-20230305223622356

完整代码：

https://gitee.com/VampireAchao/simple-mybatis.git