mybatis association , collectio

自己记录一下

定义User ，Record

public class User {
    private String user_id;
    private String user_name;
    private List<Record> recordList;
    private Record record;
}

public class Record {
    private String record_id;
    private String record_name;
}

<resultMap id="userMap" type="com.air.manager.pojo.agent.User">
        <id column="USER_ID" property="user_id" jdbcType="VARCHAR" />
        <result column="USER_NAME" property="user_name" jdbcType="VARCHAR" />

        // 一、关联单个对象 association ，如果关联对象超过一个会报错  
        //方法1 使用select属性查找selectRecordByUserId去加载
        <association property="record" column="USER_ID" select="selectRecordByUserId"/>

        //方法2 直接在内部定义record属性
        <association property="record" javaType="com.air.manager.pojo.agent.Record" >
            <id column="RECORD_ID" property="record_id" jdbcType="VARCHAR" />
            <result column="RECORD_NAME" property="record_name" jdbcType="VARCHAR" />
        </association >

        // 二、关联对象集合 collection
        //方法1 使用select属性查找selectRecordByUserId去加载
        <collection property="recordList" column="USER_ID" select="selectRecordByUserId"/>

        //方法2 直接在内部定义recordList集合 ，javaType="java.util.ArrayList"可以不添加
        <collection property="recordList" ofType="com.air.manager.pojo.agent.Record"  javaType="java.util.ArrayList" >
            <id column="RECORD_ID" property="record_id" jdbcType="VARCHAR" />
            <result column="RECORD_NAME" property="record_name" jdbcType="VARCHAR" />
        </collection>
</resultMap>

<select id="queryList" resultMap="userMap">
         SELECT 
             T.USER_ID ,
             T.USER_NAME
         FROM KING_USER T 
</select>

<resultMap id="recordMap" type="com.air.manager.pojo.agent.Record">
        <id column="RECORD_ID" property="record_id" jdbcType="VARCHAR" />
        <result column="RECORD_NAME" property="record_name" jdbcType="VARCHAR" />
</resultMap>
    
<select id="selectRecordByUserId" resultMap="recordMap">
        SELECT  
         R.RECORD_ID,
         R.RECORD_NAME
        FROM KING_RECORD R WHERE R.USER_ID=#{userId} //这里的userId名称可以随意，一样可以取到值
</select>