MyBatis nested collection query cause duplicate wrong result

Question

I use mybatis to query nested object

my bean, Goods.java

public class Goods {
private Integer goodsId;

private String goodsName;

private Integer goodsStorageNum;

private Integer goodsScore;

private GoodsStatus goodsStatus;

private String goodsDescription;

private List<GoodsImg> goodsImgList;

getter and setter here...
}

GoodsImg.java

public class Goods {
private Integer goodsId;

private String goodsName;

private Integer goodsStorageNum;

private Integer goodsScore;

private GoodsStatus goodsStatus;

private String goodsDescription;

private List<GoodsImg> goodsImgList;

getter and setter ...
}

two result map

    <!-- goods resultmap -->
<resultMap id="goodsResultMap" type="com.qunar.scoresystem.bean.Goods">
    <id property="goodsId" column="goods_id" />
    <result property="goodsName" column="goods_name" />
    <result property="goodsStorageNum" column="goods_storage_num" />
    <result property="goodsScore" column="goods_score" />
    <result property="goodsDescription" column="goods_description" />
    <result property="goodsStatus" column="goods_status" />
    <collection property="goodsImgList" column="goods_id" resultMap="goodsImgResult" />
</resultMap>

<!-- goodsimage resultmap -->
<resultMap id="goodsImgResult" type="com.qunar.scoresystem.bean.GoodsImg">
    <id property="imgId" column="img_id" />
    <result property="goodsId" column="goods_id" />
    <result property="imgDir" column="img_dir" />
    <result property="imgSize" column="img_size" />
    <result property="imgName" column="img_name" />
</resultMap>

my sql

 select goods.goods_id as goods_id, goods.goods_name as goods_name, 

 goods.goods_storage_num as goods_storage_num, goods.goods_score as goods_score, 

 goods.goods_description as goods_description, goods.goods_status as goods_status ,

 goods_img.img_name as img_name , goods_img.img_dir as img_dir , goods_img.img_size as 

 img_size 

 from goods 

 join goods_img on goods.goods_id=goods_img.goods_id limit 10; 

result of the sql in mysql

the first column below is "goods_id"

---

1 test_name 1 1 update desc 1 img1 tttt 1

1 test_name 1 1 update desc 1 img2 ttt 2

1 test_name 1 1 update desc 1 img3 ttt 3

2 test_name2 2 2 test desc2 0 df ttt 3

1 test_name 1 1 update desc 1 dfdf ddd 2

3 3333 3 3 ddfd 1 dfd sadf 1

1 test_name 1 1 update desc 1 sdfsd sdf 2

---

and the query result in java is:

List [ [Goods(id=1) with 5 GoodsImg], [Goods(id=2) with 5 GoodsImg], [Goods(id=3) with 5 GoodsImg] ]

this list contains 3 Goods all the same

and the correct list should be:

List [ [Goods(id=1) with 5 GoodsImg], [Goods(id=2) with 1 GoodsImg], [Goods(id=1) with 1 GoodsImg] ]

and, if I change the data order in mysql like this :

---

1 test_name 1 1 update desc 1 img1 tttt 1

1 test_name 1 1 update desc 1 img2 ttt 2

1 test_name 1 1 update desc 1 img3 ttt 3

2 test_name2 2 2 test desc2 0 df ttt 3

1 test_name 1 1 update desc 1 dfdf ddd 2

1 test_name 1 1 update desc 1 sdfsd sdf 2

3 3333 3 3 ddfd 1 dfd sadf 1

---

then the query result in java is:

List [ [Goods(id=1) with 5 GoodsImg], [Goods(id=1) with 5 GoodsImg], [Goods(id=3) with 1 GoodsImg] ]

still worong list, there is no Goods(id=2)

and if I change the data order in mysql like this:

---

1 test_name 1 1 update desc 1 img1 tttt 1

1 test_name 1 1 update desc 1 img2 ttt 2

1 test_name 1 1 update desc 1 img3 ttt 3

1 test_name 1 1 update desc 1 dfdf ddd 2

1 test_name 1 1 update desc 1 sdfsd sdf 2

2 test_name2 2 2 test desc2 0 df ttt 3

3 3333 3 3 ddfd 1 dfd sadf 1

---

then the query result in java is all right

since I can't control the data order in mysql, it will always return the wrong list result

so, what's the problem, is that a bug of mybatis ? my

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.2.1</version>
        </dependency>

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis-spring</artifactId>
            <version>1.2.0</version>
        </dependency>

Thx in advance

Answer 1

All right , this is an issue of mybatis, see

https://github.com/mybatis/mybatis-3/pull/22

and

https://github.com/mybatis/mybatis-3/pull/22

Answer 2

Modify join to left join in select statement will be working.