How to use a JDBI ResultSetMapper with a non default constructor

If your ResultSetMapper does not require a non default constructor, it is easy to specify a specific Mapper for a DAO method:

@SqlQuery("select id, data from person where id = :id")
Person getPerson(@Bind("id") String id);

However, sometimes the ResultSetMapper may require a non default constructor. In this case you can register a mapper with the DBI:

dbi.registerMapper(new PersonMapper(extraParameters));

JDBI will use the Mapper globally wherever the return type of the DAO method matches that of the ResultSetMapper.

If you want to use different ResultSetMapper implementations for DAO methods which return the same data type, you can register a ResultSetMapperFactory.

dbi.registerMapper(new PersonMapperFactory(extraParameters));

The ResultSetMapperFactory can return different ResultSetMapper implementations based on the StatementContext. This gives you access to things like the name of the method being called and the raw SQL.

public final class PersonMapperFactory implements ResultSetMapperFactory {

    private EmployeeMapper employeeMapper;
    private PersonMapper personMapper;

    public PersonMapperFactory(deptLookup) {
        this.employeeMapper = new EmployeeMapper(deptLookup);
        this.personMapper = new PersonMapper();

    public boolean accepts(Class type, StatementContext ctx) {
        return type.equals(Person.class);

    public ResultSetMapper mapperFor(Class type, StatementContext ctx) {        
        if (ctx.getSqlObjectMethod().getName().contains("Employee")) {
            return employeeMapper; 
        } else {
            return personMapper;

(Note that these examples use JDBI 2, I haven’t had chance to update yet…)

There’s some more info on the scope of a registered mapper in the JDBI SQL Object Reference.

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