Ordered Set with MyBatis

Question

What is the correct way to define collection implementation using MyBatis. Consider example below. I want LinkedHashSet to be returned from mapping. Where should I specify Set implementation if I don't want to have LinkedHashSet hardcoded in mapping interface.

Mapping fragment :

<select id="selectAll" resultType="Language">
    SELECT 
        <include refid="languageColumns"/>
    FROM language
    ORDER BY ord
</select>

Mapping interface :

public interface LanguageDAO {

    public Set<Language> selectAll();

}

Answer 1

MyBatis converts the result to the return type of your method.

If you use a LinkedHashSet, it will create a LinkedHashSet. But if you specify a generic interface it will use a default implementation. In the case of Set I think it is a HashSet.

You can control that behaviour replacing the default ObjectFactory by your own one. Have a look at MyBatis DefaultObjectFactory.