MyBatis - IntegerTypeHandler seems not working

Question

I'm trying to configure a default IntegerTypeHandler from org.apache.ibatis.type package of MyBatis 3.2.1 on one of my result maps.

Given the following constructor signature:

public Activity(int id, String name, String color, ActivityType type,
            int idOfOwnerClient) {
    //validations and fields initializations
}

I'm trying to transform a SQL NULL value to an int with value 0, because the field int idOfOwnerClient is optional, so, the database may have NULL values.

If a try to pass a null to a primitive type like int, an Exception will be thown, to solve that, I'm configuring a TypeHandler.

Here's a snippet of my mybatis-config.xml

<configuration>
    <typeAliases>
        <typeAlias alias="intTypeHandler" type="org.apache.ibatis.type.IntegerTypeHandler"/>
    </typeAliases>
</configuration>

and a snippet of my result map (notice the type handler of last arg element):

    <resultMap type="Activity" id="activityResult">
        <constructor>
            <idArg column="activity.id" javaType="_int"/>
            <arg column="activity.name" javaType="String"/>
            <arg column="activity.color" javaType="String"/>
            <arg resultMap="ActivityTypeMapper.activityTypeResult" javaType="ActivityType"/>
            <arg column="activity.id_client" javaType="_int" typeHandler="intTypeHandler"/>
        </constructor>
    </resultMap>

But, when I run a junit test, I get the following error (notice the null value at the end of the error):

org.mybatis.spring.MyBatisSystemException: nested exception is 
org.apache.ibatis.reflection.ReflectionException: Error instantiating class 
br.com.agrofficio.kpifarm.model.Activity with invalid types 
(int,String,String,ActivityType,int,) or values 
(2,Aplicação de Cal,FFFFFF,[Id: 1, Name: Plantio],null,). Cause: java.lang.IllegalArgumentException

As the stacktrace above proposes, I'm still getting a null value instead of 0, even with the handler applied.

Solutions that I tried with no success

1. Using the fully qualified name of the handler intead an alias on resultmap:

<arg column="activity.id_client" javaType="_int" typeHandler="org.apache.ibatis.type.IntegerTypeHandler"/>

2. Adding a type handler declaration on mybatis-config.xml:

<typeHandlers>
    <typeHandler handler="org.apache.ibatis.type.IntegerTypeHandler"/>
</typeHandlers>

Any ideas? Thanks in advance!

Answer 1

You get exceptions because you are trying to use Mybatis' default IntegerTypeHandler, which doesn't support null values (source code).

In order to satisfy your requirements, you need to implement custom typeHandler, which will inherit from default IntegerTypeHandler.

Here you'll find all information needed to implement your own typeHandler.

If you don't know where to start with your own typeHandler: This class is nearly exactly what you want. Looking at its interface makes it clear that:

• you should extend the default org.apache.ibatis.type.IntegerTypeHandler

• in your implementation both getResult() methods should be overriden