Mybatis-3: Use <include> in <resultMap>

[liujunjie]

In mapper.xml, two resultMap include the same content or one resultMap include other resultMap.

[mnesarco]

is for SQL composition. Not mapping. So, not supported any time
soon I guess.

On Thu, Sep 12, 2013 at 3:36 AM, liujunjie [email protected] wrote:

like:

Not support now ?

—
Reply to this email directly or view it on GitHubhttps://github.com/mybatis/mybatis-3/issues/81
.

Frank D. Martínez M.

[Condor70]

This would be a really useful feature!

It doesn't have to be called <include> if you are worried that people would confuse it with SQL include.

Example assuming ClassB extends ClassA:

<resultMap id="classA" class="my.package.ClassA">
  <id property="field1" column="FIELD_1" />
  <result property="field2" column="FIELD_2" />
</resultMap>
<select id="selectClassA" resultMap="classA">
  select
    A.FIELD_1,
    A.FIELD_2
  from TABLE_A A
</select>
<resultMap id="classB" class="my.package.ClassB">
  <include ref="classA" />
  <result property="field3" column="FIELD_3" />
  <result property="field4" column="FIELD_4" />
</resultMap>
<select id="selectClassB" resultMap="classB">
  select
    A.FIELD_1,
    A.FIELD_2,
    B.FIELD_3,
    B.FIELD_4
  from TABLE_A A
  inner join TABLE_B B
  on
    B.FIELD_1 = A.FIELD_1
</select>

(obviously this becomes more useful when the classA resultmap is a lot larger)

[ytfei]

Any updates on this issue? I'm also looking for such a solution.

[Condor70]

Unfortunately not, but MyBatis does have an "extends" attribute for resultmaps, e.g.

<resultMap id="classB" class="my.package.ClassB" extends="classA">
  <result property="field3" column="FIELD_3" />
  <result property="field4" column="FIELD_4" />
</resultMap>

An include option would be better, because extends is limited to one resultmap.

[ytfei]

Thanks @Condor70 , "extends" is useful for me. It would be better to have "include" :+1:

[harawata]

Hi @ytfei ,
Could you show us how your java classes and resultMaps would look like if you can use <include /> in a resultMap?
I thought extends attribute and <association /> element is sufficient for everyone's needs.

[Condor70]

extends only extends a single resultmap and <assosication /> assumes there is a nested class.

Here is a rather lengthy example of when <include /> could be useful:

public interface InterfaceA {
    public int getProperty1();
    public void setProperty1(int value);
}
public interface InterfaceB {
    public int getProperty2();
    public void setProperty2(int value);
}
public class ClassA implements InterfaceA {
    private final int id;
    private int property1;
    public ClassA(final int id) {
        super();
        this.id = id;
    }
    public int getId() {
        return this.id;
    }
    @Override
    public int getProperty1() {
        return this.property1;
    }
    @Override
    public void setProperty1(final int property1) {
        this.property1 = property1;
    }
}
public class ClassAB implements InterfaceA, InterfaceB {
    private final int id;
    private int property1;
    private int property2;
    public ClassAB(final int id) {
        super();
        this.id = id;
    }
    public int getId() {
        return this.id;
    }
    @Override
    public int getProperty1() {
        return this.property1;
    }
    @Override
    public void setProperty1(final int property1) {
        this.property1 = property1;
    }
    @Override
    public int getProperty2() {
        return this.property2;
    }
    @Override
    public void setProperty2(final int property2) {
        this.property2 = property2;
    }
}

with

<resultMap id="InterfaceA" class="my.package.InterfaceA">
  <result property="property1" column="PROPERTY_1" />
</resultMap>
<resultMap id="InterfaceB" class="my.package.InterfaceB">
  <result property="property2" column="PROPERTY_2" />
</resultMap>
<resultMap id="ClassA" class="my.package.ClassA">
  <constructor>
    <idArg column="ID" />
  </constructor>
  <include ref="InterfaceA" />
</resultMap>
<select id="selectClassA" resultMap="ClassA">
  select
    A.ID,
    A.PROPERTY_1
  from TABLE_A A
</select>
<resultMap id="ClassAB" class="my.package.ClassAB">
  <constructor>
    <idArg column="ID" />
  </constructor>
  <include ref="InterfaceA" />
  <include ref="InterfaceB" />
</resultMap>
<select id="selectClassAB" resultMap="ClassAB">
  select
    AB.ID,
    AB.PROPERTY_1,
    AB.PROPERTY_2
  from TABLE_AB AB
</select>

[Condor70]

Another option would be if extends supported multiple resultmaps. Then this would be written as:

<resultMap id="InterfaceA" class="my.package.InterfaceA">
  <result property="property1" column="PROPERTY_1" />
</resultMap>
<resultMap id="InterfaceB" class="my.package.InterfaceB">
  <result property="property2" column="PROPERTY_2" />
</resultMap>
<resultMap id="ClassA" class="my.package.ClassA" extends="InterfaceA">
  <constructor>
    <idArg column="ID" />
  </constructor>
</resultMap>
<select id="selectClassA" resultMap="ClassA">
  select
    A.ID,
    A.PROPERTY_1
  from TABLE_A A
</select>
<resultMap id="ClassAB" class="my.package.ClassAB" extends="InterfaceA,InterfaceB">
  <constructor>
    <idArg column="ID" />
  </constructor>
</resultMap>
<select id="selectClassAB" resultMap="ClassAB">
  select
    AB.ID,
    AB.PROPERTY_1,
    AB.PROPERTY_2
  from TABLE_AB AB
</select>

[harawata]

Thanks @Condor70 for the example!
Considering the current resultMap complexity (autoMapping, columnPrefix, etc.), I am a little bit anxious about adding <include /> or multiple inheritance just to reduce a little redundancy of such a rare setup, but it's just my personal opinion.

To all,
If you think you need <include /> for your resultMap, there is a good chance that existing features can help.
You should post a question on the mailing list with concrete java/mapper code.

Regards,
Iwao