refactoring - Reusing MyBatis ResultMap in multiple mapper.xml

Question

I would like to re-use a specific from different *Mapper.xml files which all somehow read same objects.

I have a Database table called Project, which I created the following resultMap for:

<resultMap id="ProjectMap" type="com.model.Project">
    <id column="id" jdbcType="BIGINT" property="id" />
    <result column="name" jdbcType="VARCHAR" property="name" />
    <result column="client_prj_no" jdbcType="VARCHAR" property="clientPrjNo" />
    <result column="notes" jdbcType="VARCHAR" property="notes" />
    <result column="start_date" jdbcType="TIMESTAMP" property="startDate" />
    ...
<resultMap>

It works great in the ProjectMapper.xml, however, now I want to create a ClientWithProjectsMapper.xml where I want to SELECT * FROM CLIENT, PROJECT where PROJECT.CLIENT_ID = CLIENT.ID and have a Client object return with a List objects. In other words, I want to get a ClientWithProjects with a single SQL.

In my mapping, I want to reuse the ProjectMap (without copy/paste) which I defined in the ProjectMapper.xml, but I am not sure how to accomplish this.

I could factor out the ProjectMap into a separate file, but I have not found any facilities in MyBatis to #include other files.

Any ideas on how this can be done? (I am using Maven, are there any plugins that would filter the files looking for #include or such, and include the contents of the file right into file being processed?).

Thanks.

-AP_

Answer 1

Once you import all the mapper xmls in mybatis-config.xml file you can refer ResultMaps configured in any of the mapper xmls using resultMap id along with namespace.

for Ex: ProjectMapper.xml

<mapper namespace="com.mybatisapp.mappers.ProjectMapper">
    <resultMap id="ProjectMap" type="com.model.Project">
        <id column="id" jdbcType="BIGINT" property="id" />
        <result column="name" jdbcType="VARCHAR" property="name" />     
    <resultMap>
</mapper>

In ClientWithProjectsMapper.xml

    <select id="selectProjectsByClient" parameterType="int" 
resultMap="com.mybatisapp.mappers.ProjectMapper.ProjectMap">
    select * from blahblah
    </select>

Here you can reference resultMap in another Mapper xml files using fully qualified name as "com.mybatisapp.mappers.ProjectMapper.ProjectMap"