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https://gitee.com/best_handsome/mybatis-plus-join
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135 lines
3.5 KiB
Markdown
135 lines
3.5 KiB
Markdown
# mybatis-plus-join
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* 本页功能只能在1.2.0测试版中使用,最新版本 1.2.0.Beta6
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* 点个Star支持一下吧 :)
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QQ群:1022221898
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## 使用方法
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### 安装
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- Maven
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```xml
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<dependency>
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<groupId>com.github.yulichang</groupId>
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<artifactId>mybatis-plus-join</artifactId>
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<version>1.2.0.Beta6</version>
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</dependency>
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```
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- Gradle
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```
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implementation group: 'com.github.yulichang', name: 'mybatis-plus-join', version: '1.2.0.Beta6'
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```
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或者clone代码到本地执行 mvn install, 再引入以上依赖
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<br>
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注意: mybatis plus version >= 3.4.0
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<br>
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### 使用
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* mapper继承MPJBaseMapper
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* service继承MPJBaseService (可选)
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* serviceImpl继承MPJBaseServiceImpl (可选)
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#### @EntityMapping 和 @FieldMapping 注解
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UserDO.java
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```java
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@Data
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@TableName("user")
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public class UserDO {
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@TableId
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private Integer id;
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private Integer pid;//父id
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/* 其他属性略 */
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/**
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* 查询上级 一对一
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*/
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@TableField(exist = false)
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@EntityMapping(thisField = "pid", joinField = "id")
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private UserDO pUser;
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/**
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* 查询下级 一对多
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*/
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@TableField(exist = false)
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@EntityMapping(thisField = "id", joinField = "pid")
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private List<UserDO> childUser;
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/**
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* 查询地址 (一对多)
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*/
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@TableField(exist = false)
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@EntityMapping(thisField = "id", joinField = "userId")
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private List<UserAddressDO> addressList;
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/**
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* 绑定字段 （一对多）
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*/
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@TableField(exist = false)
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@FieldMapping(tag = UserDO.class, thisField = "id", joinField = "pid", select = "id")
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private List<Integer> childIds;
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}
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```
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使用
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```java
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/**
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* 一对一，一对多关系映射查询
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* 映射只对以Deep结尾有效，比如 getByIdDeep listByIdsDeep 等
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* 如果不需要关系映射就使用mybatis plus原生方法即可，比如 getById listByIds 等
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*
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* 注意：关系映射不会去关联查询，而是执行多次单表查询（对结果汇总后使用in语句查询,再对结果进行匹配）
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*/
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@SpringBootTest
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class MappingTest {
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@Resource
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private UserMapper userMapper;
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@Test
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void test1() {
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UserDO deep = userMapper.selectByIdDeep(2);
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System.out.println(deep);
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}
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@Test
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void test2() {
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List<UserDO> list = userMapper.selectListDeep(Wrappers.emptyWrapper());
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list.forEach(System.out::println);
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}
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@Test
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void test3() {
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Page<UserDO> page = userMapper.selectPageDeep(new Page<>(2, 2), Wrappers.emptyWrapper());
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page.getRecords().forEach(System.out::println);
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}
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/**
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* 更多方法请查阅 MPJDeepMapper 或者 MPJDeepService
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* 使用方式与 mybatis plus 一致
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*/
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}
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```
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MPJMapping 说明：
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* @EntityMapping / @FieldMapping tag 关联实体类
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* @EntityMapping / @FieldMapping thisField 当前类关联对应的字段的属性名，可以不填，默认为当前类的主键
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* @EntityMapping / @FieldMapping joinField 关联类对应的字段的属性名，可以不填，默认为关联类的主键
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* @EntityMapping / @FieldMapping isThrowExp 一对一查询时,如果查询到多条记录是否抛出异常,true:抛出异常,false:获取列表第一条数据
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*
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更多功能请看代码注释 [EntityMapping](https://gitee.com/best_handsome/mybatis-plus-join/blob/master/src/main/java/com/github/yulichang/annotation/EntityMapping.java)
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[FieldMapping](https://gitee.com/best_handsome/mybatis-plus-join/blob/master/src/main/java/com/github/yulichang/annotation/FieldMapping.java)
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