Inheritance via discriminator field

From version 7.0.0

To configure the inheritance you will just need to call one of the discriminator method on the XXXXMapperFactory.

For example

JdbcMapper<Person> mapper =
        JdbcMapperFactory.newInstance()
                .addKeys("id", "students_id")
                .discriminator(Person.class)
                .onColumn("person_type", String.class)
                .with( 
                    builder -> 
                        builder
                            .when("student", Student.class)
                            .when("professor", Professor.class)
                )
                .newMapper(Foo.class);

That will create a mapper that will either create a Student object when the person_type column is equals to "student" or a Person when equals to "professor".

It is also possible to use a Predicate instead of a value to match.

JdbcMapper<Person> mapper =
        JdbcMapperFactory.newInstance()
                .addKeys("id", "students_id")
                .discriminator(Person.class)
                .onColumn("person_type", String.class)
                .with( 
                    builder -> builder
                        .when(v -> "student".equals(v), Student.class)
                        .when(v -> true, Professor.class)
                )
                .newMapper(Foo.class);

In that case it will instantiate a Student when person_type is "student" otherwise it will default to Professor.

Since version 6.0.1 - effectively from 6.0.0 but the following doc is for 6.0.1 - SimpleFlatMapper support inheritance via discriminator field at any level of the object tree for all mappers - csv, jdbc etc… -.

To configure the inheritance you will just need to call one of the discriminator method on the XXXXMapperFactory.

For example

JdbcMapper<Person> mapper =
        JdbcMapperFactory.newInstance()
                .addKeys("id", "students_id")
                .discriminator(Person.class, 
                            "person_type", 
                            ResultSet::getString, 
                            builder -> 
                                builder
                                    .when("student", Student.class)
                                    .when("professor", Professor.class)
                )
                .newMapper(Foo.class);

That will create a mapper that will either create a Student object when the person_type column is equals to "student" or a Person when equals to "professor".

It is also possible to use a Predicate instead of a value to match.

JdbcMapper<Person> mapper =
        JdbcMapperFactory.newInstance()
                .addKeys("id", "students_id")
                .discriminator(
                            Person.class, 
                            "person_type", 
                            ResultSet::getString, 
                            builder -> builder
                                .when(v -> "student".equals(v), Student.class)
                                .when(v -> true, Professor.class)
                )
                .newMapper(Foo.class);

In that case it will instantiate a Student when person_type is "student" otherwise it will default to Professor.

If you need to discriminate on more that one column you will need to use the Predicate.

JdbcMapper<Person> mapper =
        JdbcMapperFactory.newInstance()
                .addKeys("id", "students_id")
                .discriminator(
                        Person.class, 
                        builder -> 
                            builder
                                .when(rs -> {
                                    try {
                                        return 
                                            "student"
                                                .equals(rs.getString("person_type"));
                                    } catch (Exception e) {
                                        return ErrorHelper.rethrow(e);
                                    }
                                }, Student.class)
                                .when(rs -> true, Professor.class)
                )
                .newMapper(Foo.class);